From fcf634098c00dd9cd247447368495f0b79be12d1 Mon Sep 17 00:00:00 2001 From: Christopher Yeoh Date: Mon, 31 Oct 2011 17:06:39 -0700 Subject: Cross Memory Attach The basic idea behind cross memory attach is to allow MPI programs doing intra-node communication to do a single copy of the message rather than a double copy of the message via shared memory. The following patch attempts to achieve this by allowing a destination process, given an address and size from a source process, to copy memory directly from the source process into its own address space via a system call. There is also a symmetrical ability to copy from the current process's address space into a destination process's address space. - Use of /proc/pid/mem has been considered, but there are issues with using it: - Does not allow for specifying iovecs for both src and dest, assuming preadv or pwritev was implemented either the area read from or written to would need to be contiguous. - Currently mem_read allows only processes who are currently ptrace'ing the target and are still able to ptrace the target to read from the target. This check could possibly be moved to the open call, but its not clear exactly what race this restriction is stopping (reason appears to have been lost) - Having to send the fd of /proc/self/mem via SCM_RIGHTS on unix domain socket is a bit ugly from a userspace point of view, especially when you may have hundreds if not (eventually) thousands of processes that all need to do this with each other - Doesn't allow for some future use of the interface we would like to consider adding in the future (see below) - Interestingly reading from /proc/pid/mem currently actually involves two copies! (But this could be fixed pretty easily) As mentioned previously use of vmsplice instead was considered, but has problems. Since you need the reader and writer working co-operatively if the pipe is not drained then you block. Which requires some wrapping to do non blocking on the send side or polling on the receive. In all to all communication it requires ordering otherwise you can deadlock. And in the example of many MPI tasks writing to one MPI task vmsplice serialises the copying. There are some cases of MPI collectives where even a single copy interface does not get us the performance gain we could. For example in an MPI_Reduce rather than copy the data from the source we would like to instead use it directly in a mathops (say the reduce is doing a sum) as this would save us doing a copy. We don't need to keep a copy of the data from the source. I haven't implemented this, but I think this interface could in the future do all this through the use of the flags - eg could specify the math operation and type and the kernel rather than just copying the data would apply the specified operation between the source and destination and store it in the destination. Although we don't have a "second user" of the interface (though I've had some nibbles from people who may be interested in using it for intra process messaging which is not MPI). This interface is something which hardware vendors are already doing for their custom drivers to implement fast local communication. And so in addition to this being useful for OpenMPI it would mean the driver maintainers don't have to fix things up when the mm changes. There was some discussion about how much faster a true zero copy would go. Here's a link back to the email with some testing I did on that: http://marc.info/?l=linux-mm&m=130105930902915&w=2 There is a basic man page for the proposed interface here: http://ozlabs.org/~cyeoh/cma/process_vm_readv.txt This has been implemented for x86 and powerpc, other architecture should mainly (I think) just need to add syscall numbers for the process_vm_readv and process_vm_writev. There are 32 bit compatibility versions for 64-bit kernels. For arch maintainers there are some simple tests to be able to quickly verify that the syscalls are working correctly here: http://ozlabs.org/~cyeoh/cma/cma-test-20110718.tgz Signed-off-by: Chris Yeoh Cc: Ingo Molnar Cc: "H. Peter Anvin" Cc: Thomas Gleixner Cc: Arnd Bergmann Cc: Paul Mackerras Cc: Benjamin Herrenschmidt Cc: David Howells Cc: James Morris Cc: Cc: Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- mm/Makefile | 3 +- mm/process_vm_access.c | 496 +++++++++++++++++++++++++++++++++++++++++++++++++ 2 files changed, 498 insertions(+), 1 deletion(-) create mode 100644 mm/process_vm_access.c (limited to 'mm') diff --git a/mm/Makefile b/mm/Makefile index 836e4163c1bf..50ec00ef2a0e 100644 --- a/mm/Makefile +++ b/mm/Makefile @@ -5,7 +5,8 @@ mmu-y := nommu.o mmu-$(CONFIG_MMU) := fremap.o highmem.o madvise.o memory.o mincore.o \ mlock.o mmap.o mprotect.o mremap.o msync.o rmap.o \ - vmalloc.o pagewalk.o pgtable-generic.o + vmalloc.o pagewalk.o pgtable-generic.o \ + process_vm_access.o obj-y := filemap.o mempool.o oom_kill.o fadvise.o \ maccess.o page_alloc.o page-writeback.o \ diff --git a/mm/process_vm_access.c b/mm/process_vm_access.c new file mode 100644 index 000000000000..e920aa3ce104 --- /dev/null +++ b/mm/process_vm_access.c @@ -0,0 +1,496 @@ +/* + * linux/mm/process_vm_access.c + * + * Copyright (C) 2010-2011 Christopher Yeoh , IBM Corp. + * + * This program is free software; you can redistribute it and/or + * modify it under the terms of the GNU General Public License + * as published by the Free Software Foundation; either version + * 2 of the License, or (at your option) any later version. + */ + +#include +#include +#include +#include +#include +#include +#include + +#ifdef CONFIG_COMPAT +#include +#endif + +/** + * process_vm_rw_pages - read/write pages from task specified + * @task: task to read/write from + * @mm: mm for task + * @process_pages: struct pages area that can store at least + * nr_pages_to_copy struct page pointers + * @pa: address of page in task to start copying from/to + * @start_offset: offset in page to start copying from/to + * @len: number of bytes to copy + * @lvec: iovec array specifying where to copy to/from + * @lvec_cnt: number of elements in iovec array + * @lvec_current: index in iovec array we are up to + * @lvec_offset: offset in bytes from current iovec iov_base we are up to + * @vm_write: 0 means copy from, 1 means copy to + * @nr_pages_to_copy: number of pages to copy + * @bytes_copied: returns number of bytes successfully copied + * Returns 0 on success, error code otherwise + */ +static int process_vm_rw_pages(struct task_struct *task, + struct mm_struct *mm, + struct page **process_pages, + unsigned long pa, + unsigned long start_offset, + unsigned long len, + const struct iovec *lvec, + unsigned long lvec_cnt, + unsigned long *lvec_current, + size_t *lvec_offset, + int vm_write, + unsigned int nr_pages_to_copy, + ssize_t *bytes_copied) +{ + int pages_pinned; + void *target_kaddr; + int pgs_copied = 0; + int j; + int ret; + ssize_t bytes_to_copy; + ssize_t rc = 0; + + *bytes_copied = 0; + + /* Get the pages we're interested in */ + down_read(&mm->mmap_sem); + pages_pinned = get_user_pages(task, mm, pa, + nr_pages_to_copy, + vm_write, 0, process_pages, NULL); + up_read(&mm->mmap_sem); + + if (pages_pinned != nr_pages_to_copy) { + rc = -EFAULT; + goto end; + } + + /* Do the copy for each page */ + for (pgs_copied = 0; + (pgs_copied < nr_pages_to_copy) && (*lvec_current < lvec_cnt); + pgs_copied++) { + /* Make sure we have a non zero length iovec */ + while (*lvec_current < lvec_cnt + && lvec[*lvec_current].iov_len == 0) + (*lvec_current)++; + if (*lvec_current == lvec_cnt) + break; + + /* + * Will copy smallest of: + * - bytes remaining in page + * - bytes remaining in destination iovec + */ + bytes_to_copy = min_t(ssize_t, PAGE_SIZE - start_offset, + len - *bytes_copied); + bytes_to_copy = min_t(ssize_t, bytes_to_copy, + lvec[*lvec_current].iov_len + - *lvec_offset); + + target_kaddr = kmap(process_pages[pgs_copied]) + start_offset; + + if (vm_write) + ret = copy_from_user(target_kaddr, + lvec[*lvec_current].iov_base + + *lvec_offset, + bytes_to_copy); + else + ret = copy_to_user(lvec[*lvec_current].iov_base + + *lvec_offset, + target_kaddr, bytes_to_copy); + kunmap(process_pages[pgs_copied]); + if (ret) { + *bytes_copied += bytes_to_copy - ret; + pgs_copied++; + rc = -EFAULT; + goto end; + } + *bytes_copied += bytes_to_copy; + *lvec_offset += bytes_to_copy; + if (*lvec_offset == lvec[*lvec_current].iov_len) { + /* + * Need to copy remaining part of page into the + * next iovec if there are any bytes left in page + */ + (*lvec_current)++; + *lvec_offset = 0; + start_offset = (start_offset + bytes_to_copy) + % PAGE_SIZE; + if (start_offset) + pgs_copied--; + } else { + start_offset = 0; + } + } + +end: + if (vm_write) { + for (j = 0; j < pages_pinned; j++) { + if (j < pgs_copied) + set_page_dirty_lock(process_pages[j]); + put_page(process_pages[j]); + } + } else { + for (j = 0; j < pages_pinned; j++) + put_page(process_pages[j]); + } + + return rc; +} + +/* Maximum number of pages kmalloc'd to hold struct page's during copy */ +#define PVM_MAX_KMALLOC_PAGES (PAGE_SIZE * 2) + +/** + * process_vm_rw_single_vec - read/write pages from task specified + * @addr: start memory address of target process + * @len: size of area to copy to/from + * @lvec: iovec array specifying where to copy to/from locally + * @lvec_cnt: number of elements in iovec array + * @lvec_current: index in iovec array we are up to + * @lvec_offset: offset in bytes from current iovec iov_base we are up to + * @process_pages: struct pages area that can store at least + * nr_pages_to_copy struct page pointers + * @mm: mm for task + * @task: task to read/write from + * @vm_write: 0 means copy from, 1 means copy to + * @bytes_copied: returns number of bytes successfully copied + * Returns 0 on success or on failure error code + */ +static int process_vm_rw_single_vec(unsigned long addr, + unsigned long len, + const struct iovec *lvec, + unsigned long lvec_cnt, + unsigned long *lvec_current, + size_t *lvec_offset, + struct page **process_pages, + struct mm_struct *mm, + struct task_struct *task, + int vm_write, + ssize_t *bytes_copied) +{ + unsigned long pa = addr & PAGE_MASK; + unsigned long start_offset = addr - pa; + unsigned long nr_pages; + ssize_t bytes_copied_loop; + ssize_t rc = 0; + unsigned long nr_pages_copied = 0; + unsigned long nr_pages_to_copy; + unsigned long max_pages_per_loop = PVM_MAX_KMALLOC_PAGES + / sizeof(struct pages *); + + *bytes_copied = 0; + + /* Work out address and page range required */ + if (len == 0) + return 0; + nr_pages = (addr + len - 1) / PAGE_SIZE - addr / PAGE_SIZE + 1; + + while ((nr_pages_copied < nr_pages) && (*lvec_current < lvec_cnt)) { + nr_pages_to_copy = min(nr_pages - nr_pages_copied, + max_pages_per_loop); + + rc = process_vm_rw_pages(task, mm, process_pages, pa, + start_offset, len, + lvec, lvec_cnt, + lvec_current, lvec_offset, + vm_write, nr_pages_to_copy, + &bytes_copied_loop); + start_offset = 0; + *bytes_copied += bytes_copied_loop; + + if (rc < 0) { + return rc; + } else { + len -= bytes_copied_loop; + nr_pages_copied += nr_pages_to_copy; + pa += nr_pages_to_copy * PAGE_SIZE; + } + } + + return rc; +} + +/* Maximum number of entries for process pages array + which lives on stack */ +#define PVM_MAX_PP_ARRAY_COUNT 16 + +/** + * process_vm_rw_core - core of reading/writing pages from task specified + * @pid: PID of process to read/write from/to + * @lvec: iovec array specifying where to copy to/from locally + * @liovcnt: size of lvec array + * @rvec: iovec array specifying where to copy to/from in the other process + * @riovcnt: size of rvec array + * @flags: currently unused + * @vm_write: 0 if reading from other process, 1 if writing to other process + * Returns the number of bytes read/written or error code. May + * return less bytes than expected if an error occurs during the copying + * process. + */ +static ssize_t process_vm_rw_core(pid_t pid, const struct iovec *lvec, + unsigned long liovcnt, + const struct iovec *rvec, + unsigned long riovcnt, + unsigned long flags, int vm_write) +{ + struct task_struct *task; + struct page *pp_stack[PVM_MAX_PP_ARRAY_COUNT]; + struct page **process_pages = pp_stack; + struct mm_struct *mm; + unsigned long i; + ssize_t rc = 0; + ssize_t bytes_copied_loop; + ssize_t bytes_copied = 0; + unsigned long nr_pages = 0; + unsigned long nr_pages_iov; + unsigned long iov_l_curr_idx = 0; + size_t iov_l_curr_offset = 0; + ssize_t iov_len; + + /* + * Work out how many pages of struct pages we're going to need + * when eventually calling get_user_pages + */ + for (i = 0; i < riovcnt; i++) { + iov_len = rvec[i].iov_len; + if (iov_len > 0) { + nr_pages_iov = ((unsigned long)rvec[i].iov_base + + iov_len) + / PAGE_SIZE - (unsigned long)rvec[i].iov_base + / PAGE_SIZE + 1; + nr_pages = max(nr_pages, nr_pages_iov); + } + } + + if (nr_pages == 0) + return 0; + + if (nr_pages > PVM_MAX_PP_ARRAY_COUNT) { + /* For reliability don't try to kmalloc more than + 2 pages worth */ + process_pages = kmalloc(min_t(size_t, PVM_MAX_KMALLOC_PAGES, + sizeof(struct pages *)*nr_pages), + GFP_KERNEL); + + if (!process_pages) + return -ENOMEM; + } + + /* Get process information */ + rcu_read_lock(); + task = find_task_by_vpid(pid); + if (task) + get_task_struct(task); + rcu_read_unlock(); + if (!task) { + rc = -ESRCH; + goto free_proc_pages; + } + + task_lock(task); + if (__ptrace_may_access(task, PTRACE_MODE_ATTACH)) { + task_unlock(task); + rc = -EPERM; + goto put_task_struct; + } + mm = task->mm; + + if (!mm || (task->flags & PF_KTHREAD)) { + task_unlock(task); + rc = -EINVAL; + goto put_task_struct; + } + + atomic_inc(&mm->mm_users); + task_unlock(task); + + for (i = 0; i < riovcnt && iov_l_curr_idx < liovcnt; i++) { + rc = process_vm_rw_single_vec( + (unsigned long)rvec[i].iov_base, rvec[i].iov_len, + lvec, liovcnt, &iov_l_curr_idx, &iov_l_curr_offset, + process_pages, mm, task, vm_write, &bytes_copied_loop); + bytes_copied += bytes_copied_loop; + if (rc != 0) { + /* If we have managed to copy any data at all then + we return the number of bytes copied. Otherwise + we return the error code */ + if (bytes_copied) + rc = bytes_copied; + goto put_mm; + } + } + + rc = bytes_copied; +put_mm: + mmput(mm); + +put_task_struct: + put_task_struct(task); + +free_proc_pages: + if (process_pages != pp_stack) + kfree(process_pages); + return rc; +} + +/** + * process_vm_rw - check iovecs before calling core routine + * @pid: PID of process to read/write from/to + * @lvec: iovec array specifying where to copy to/from locally + * @liovcnt: size of lvec array + * @rvec: iovec array specifying where to copy to/from in the other process + * @riovcnt: size of rvec array + * @flags: currently unused + * @vm_write: 0 if reading from other process, 1 if writing to other process + * Returns the number of bytes read/written or error code. May + * return less bytes than expected if an error occurs during the copying + * process. + */ +static ssize_t process_vm_rw(pid_t pid, + const struct iovec __user *lvec, + unsigned long liovcnt, + const struct iovec __user *rvec, + unsigned long riovcnt, + unsigned long flags, int vm_write) +{ + struct iovec iovstack_l[UIO_FASTIOV]; + struct iovec iovstack_r[UIO_FASTIOV]; + struct iovec *iov_l = iovstack_l; + struct iovec *iov_r = iovstack_r; + ssize_t rc; + + if (flags != 0) + return -EINVAL; + + /* Check iovecs */ + if (vm_write) + rc = rw_copy_check_uvector(WRITE, lvec, liovcnt, UIO_FASTIOV, + iovstack_l, &iov_l, 1); + else + rc = rw_copy_check_uvector(READ, lvec, liovcnt, UIO_FASTIOV, + iovstack_l, &iov_l, 1); + if (rc <= 0) + goto free_iovecs; + + rc = rw_copy_check_uvector(READ, rvec, riovcnt, UIO_FASTIOV, + iovstack_r, &iov_r, 0); + if (rc <= 0) + goto free_iovecs; + + rc = process_vm_rw_core(pid, iov_l, liovcnt, iov_r, riovcnt, flags, + vm_write); + +free_iovecs: + if (iov_r != iovstack_r) + kfree(iov_r); + if (iov_l != iovstack_l) + kfree(iov_l); + + return rc; +} + +SYSCALL_DEFINE6(process_vm_readv, pid_t, pid, const struct iovec __user *, lvec, + unsigned long, liovcnt, const struct iovec __user *, rvec, + unsigned long, riovcnt, unsigned long, flags) +{ + return process_vm_rw(pid, lvec, liovcnt, rvec, riovcnt, flags, 0); +} + +SYSCALL_DEFINE6(process_vm_writev, pid_t, pid, + const struct iovec __user *, lvec, + unsigned long, liovcnt, const struct iovec __user *, rvec, + unsigned long, riovcnt, unsigned long, flags) +{ + return process_vm_rw(pid, lvec, liovcnt, rvec, riovcnt, flags, 1); +} + +#ifdef CONFIG_COMPAT + +asmlinkage ssize_t +compat_process_vm_rw(compat_pid_t pid, + const struct compat_iovec __user *lvec, + unsigned long liovcnt, + const struct compat_iovec __user *rvec, + unsigned long riovcnt, + unsigned long flags, int vm_write) +{ + struct iovec iovstack_l[UIO_FASTIOV]; + struct iovec iovstack_r[UIO_FASTIOV]; + struct iovec *iov_l = iovstack_l; + struct iovec *iov_r = iovstack_r; + ssize_t rc = -EFAULT; + + if (flags != 0) + return -EINVAL; + + if (!access_ok(VERIFY_READ, lvec, liovcnt * sizeof(*lvec))) + goto out; + + if (!access_ok(VERIFY_READ, rvec, riovcnt * sizeof(*rvec))) + goto out; + + if (vm_write) + rc = compat_rw_copy_check_uvector(WRITE, lvec, liovcnt, + UIO_FASTIOV, iovstack_l, + &iov_l, 1); + else + rc = compat_rw_copy_check_uvector(READ, lvec, liovcnt, + UIO_FASTIOV, iovstack_l, + &iov_l, 1); + if (rc <= 0) + goto free_iovecs; + rc = compat_rw_copy_check_uvector(READ, rvec, riovcnt, + UIO_FASTIOV, iovstack_r, + &iov_r, 0); + if (rc <= 0) + goto free_iovecs; + + rc = process_vm_rw_core(pid, iov_l, liovcnt, iov_r, riovcnt, flags, + vm_write); + +free_iovecs: + if (iov_r != iovstack_r) + kfree(iov_r); + if (iov_l != iovstack_l) + kfree(iov_l); + +out: + return rc; +} + +asmlinkage ssize_t +compat_sys_process_vm_readv(compat_pid_t pid, + const struct compat_iovec __user *lvec, + unsigned long liovcnt, + const struct compat_iovec __user *rvec, + unsigned long riovcnt, + unsigned long flags) +{ + return compat_process_vm_rw(pid, lvec, liovcnt, rvec, + riovcnt, flags, 0); +} + +asmlinkage ssize_t +compat_sys_process_vm_writev(compat_pid_t pid, + const struct compat_iovec __user *lvec, + unsigned long liovcnt, + const struct compat_iovec __user *rvec, + unsigned long riovcnt, + unsigned long flags) +{ + return compat_process_vm_rw(pid, lvec, liovcnt, rvec, + riovcnt, flags, 1); +} + +#endif -- cgit v1.2.3 From b9e84ac1536d35aee03b2601f19694949f0bd506 Mon Sep 17 00:00:00 2001 From: Minchan Kim Date: Mon, 31 Oct 2011 17:06:44 -0700 Subject: mm: compaction: trivial clean up in acct_isolated() acct_isolated of compaction uses page_lru_base_type which returns only base type of LRU list so it never returns LRU_ACTIVE_ANON or LRU_ACTIVE_FILE. In addtion, cc->nr_[anon|file] is used in only acct_isolated so it doesn't have fields in conpact_control. This patch removes fields from compact_control and makes clear function of acct_issolated which counts the number of anon|file pages isolated. Signed-off-by: Minchan Kim Acked-by: Johannes Weiner Reviewed-by: KAMEZAWA Hiroyuki Reviewed-by: KOSAKI Motohiro Acked-by: Mel Gorman Acked-by: Rik van Riel Reviewed-by: Michal Hocko Cc: Andrea Arcangeli Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- mm/compaction.c | 18 +++++------------- 1 file changed, 5 insertions(+), 13 deletions(-) (limited to 'mm') diff --git a/mm/compaction.c b/mm/compaction.c index 6cc604bd5649..b2977a5d659a 100644 --- a/mm/compaction.c +++ b/mm/compaction.c @@ -35,10 +35,6 @@ struct compact_control { unsigned long migrate_pfn; /* isolate_migratepages search base */ bool sync; /* Synchronous migration */ - /* Account for isolated anon and file pages */ - unsigned long nr_anon; - unsigned long nr_file; - unsigned int order; /* order a direct compactor needs */ int migratetype; /* MOVABLE, RECLAIMABLE etc */ struct zone *zone; @@ -223,17 +219,13 @@ static void isolate_freepages(struct zone *zone, static void acct_isolated(struct zone *zone, struct compact_control *cc) { struct page *page; - unsigned int count[NR_LRU_LISTS] = { 0, }; + unsigned int count[2] = { 0, }; - list_for_each_entry(page, &cc->migratepages, lru) { - int lru = page_lru_base_type(page); - count[lru]++; - } + list_for_each_entry(page, &cc->migratepages, lru) + count[!!page_is_file_cache(page)]++; - cc->nr_anon = count[LRU_ACTIVE_ANON] + count[LRU_INACTIVE_ANON]; - cc->nr_file = count[LRU_ACTIVE_FILE] + count[LRU_INACTIVE_FILE]; - __mod_zone_page_state(zone, NR_ISOLATED_ANON, cc->nr_anon); - __mod_zone_page_state(zone, NR_ISOLATED_FILE, cc->nr_file); + __mod_zone_page_state(zone, NR_ISOLATED_ANON, count[0]); + __mod_zone_page_state(zone, NR_ISOLATED_FILE, count[1]); } /* Similar to reclaim, but different enough that they don't share logic */ -- cgit v1.2.3 From 4356f21d09283dc6d39a6f7287a65ddab61e2808 Mon Sep 17 00:00:00 2001 From: Minchan Kim Date: Mon, 31 Oct 2011 17:06:47 -0700 Subject: mm: change isolate mode from #define to bitwise type Change ISOLATE_XXX macro with bitwise isolate_mode_t type. Normally, macro isn't recommended as it's type-unsafe and making debugging harder as symbol cannot be passed throught to the debugger. Quote from Johannes " Hmm, it would probably be cleaner to fully convert the isolation mode into independent flags. INACTIVE, ACTIVE, BOTH is currently a tri-state among flags, which is a bit ugly." This patch moves isolate mode from swap.h to mmzone.h by memcontrol.h Signed-off-by: Minchan Kim Cc: Johannes Weiner Cc: KAMEZAWA Hiroyuki Cc: KOSAKI Motohiro Cc: Mel Gorman Cc: Rik van Riel Cc: Michal Hocko Cc: Andrea Arcangeli Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- .../trace/postprocess/trace-vmscan-postprocess.pl | 8 ++--- include/linux/memcontrol.h | 3 +- include/linux/mmzone.h | 8 +++++ include/linux/swap.h | 7 +--- include/trace/events/vmscan.h | 8 ++--- mm/compaction.c | 3 +- mm/memcontrol.c | 3 +- mm/vmscan.c | 37 ++++++++++++---------- 8 files changed, 43 insertions(+), 34 deletions(-) (limited to 'mm') diff --git a/Documentation/trace/postprocess/trace-vmscan-postprocess.pl b/Documentation/trace/postprocess/trace-vmscan-postprocess.pl index 12cecc83cd91..4a37c4759cd2 100644 --- a/Documentation/trace/postprocess/trace-vmscan-postprocess.pl +++ b/Documentation/trace/postprocess/trace-vmscan-postprocess.pl @@ -379,10 +379,10 @@ EVENT_PROCESS: # To closer match vmstat scanning statistics, only count isolate_both # and isolate_inactive as scanning. isolate_active is rotation - # isolate_inactive == 0 - # isolate_active == 1 - # isolate_both == 2 - if ($isolate_mode != 1) { + # isolate_inactive == 1 + # isolate_active == 2 + # isolate_both == 3 + if ($isolate_mode != 2) { $perprocesspid{$process_pid}->{HIGH_NR_SCANNED} += $nr_scanned; } $perprocesspid{$process_pid}->{HIGH_NR_CONTIG_DIRTY} += $nr_contig_dirty; diff --git a/include/linux/memcontrol.h b/include/linux/memcontrol.h index 343bd7661f2a..ac797fa03ef8 100644 --- a/include/linux/memcontrol.h +++ b/include/linux/memcontrol.h @@ -35,7 +35,8 @@ enum mem_cgroup_page_stat_item { extern unsigned long mem_cgroup_isolate_pages(unsigned long nr_to_scan, struct list_head *dst, unsigned long *scanned, int order, - int mode, struct zone *z, + isolate_mode_t mode, + struct zone *z, struct mem_cgroup *mem_cont, int active, int file); diff --git a/include/linux/mmzone.h b/include/linux/mmzone.h index be1ac8d7789b..436ce6e7a446 100644 --- a/include/linux/mmzone.h +++ b/include/linux/mmzone.h @@ -164,6 +164,14 @@ static inline int is_unevictable_lru(enum lru_list l) #define LRU_ALL_EVICTABLE (LRU_ALL_FILE | LRU_ALL_ANON) #define LRU_ALL ((1 << NR_LRU_LISTS) - 1) +/* Isolate inactive pages */ +#define ISOLATE_INACTIVE ((__force isolate_mode_t)0x1) +/* Isolate active pages */ +#define ISOLATE_ACTIVE ((__force isolate_mode_t)0x2) + +/* LRU Isolation modes. */ +typedef unsigned __bitwise__ isolate_mode_t; + enum zone_watermarks { WMARK_MIN, WMARK_LOW, diff --git a/include/linux/swap.h b/include/linux/swap.h index c71f84bb62ec..1e22e126d2ac 100644 --- a/include/linux/swap.h +++ b/include/linux/swap.h @@ -243,15 +243,10 @@ static inline void lru_cache_add_file(struct page *page) __lru_cache_add(page, LRU_INACTIVE_FILE); } -/* LRU Isolation modes. */ -#define ISOLATE_INACTIVE 0 /* Isolate inactive pages. */ -#define ISOLATE_ACTIVE 1 /* Isolate active pages. */ -#define ISOLATE_BOTH 2 /* Isolate both active and inactive pages. */ - /* linux/mm/vmscan.c */ extern unsigned long try_to_free_pages(struct zonelist *zonelist, int order, gfp_t gfp_mask, nodemask_t *mask); -extern int __isolate_lru_page(struct page *page, int mode, int file); +extern int __isolate_lru_page(struct page *page, isolate_mode_t mode, int file); extern unsigned long try_to_free_mem_cgroup_pages(struct mem_cgroup *mem, gfp_t gfp_mask, bool noswap); extern unsigned long mem_cgroup_shrink_node_zone(struct mem_cgroup *mem, diff --git a/include/trace/events/vmscan.h b/include/trace/events/vmscan.h index 36851f7f13da..edc4b3d25a2d 100644 --- a/include/trace/events/vmscan.h +++ b/include/trace/events/vmscan.h @@ -266,7 +266,7 @@ DECLARE_EVENT_CLASS(mm_vmscan_lru_isolate_template, unsigned long nr_lumpy_taken, unsigned long nr_lumpy_dirty, unsigned long nr_lumpy_failed, - int isolate_mode), + isolate_mode_t isolate_mode), TP_ARGS(order, nr_requested, nr_scanned, nr_taken, nr_lumpy_taken, nr_lumpy_dirty, nr_lumpy_failed, isolate_mode), @@ -278,7 +278,7 @@ DECLARE_EVENT_CLASS(mm_vmscan_lru_isolate_template, __field(unsigned long, nr_lumpy_taken) __field(unsigned long, nr_lumpy_dirty) __field(unsigned long, nr_lumpy_failed) - __field(int, isolate_mode) + __field(isolate_mode_t, isolate_mode) ), TP_fast_assign( @@ -312,7 +312,7 @@ DEFINE_EVENT(mm_vmscan_lru_isolate_template, mm_vmscan_lru_isolate, unsigned long nr_lumpy_taken, unsigned long nr_lumpy_dirty, unsigned long nr_lumpy_failed, - int isolate_mode), + isolate_mode_t isolate_mode), TP_ARGS(order, nr_requested, nr_scanned, nr_taken, nr_lumpy_taken, nr_lumpy_dirty, nr_lumpy_failed, isolate_mode) @@ -327,7 +327,7 @@ DEFINE_EVENT(mm_vmscan_lru_isolate_template, mm_vmscan_memcg_isolate, unsigned long nr_lumpy_taken, unsigned long nr_lumpy_dirty, unsigned long nr_lumpy_failed, - int isolate_mode), + isolate_mode_t isolate_mode), TP_ARGS(order, nr_requested, nr_scanned, nr_taken, nr_lumpy_taken, nr_lumpy_dirty, nr_lumpy_failed, isolate_mode) diff --git a/mm/compaction.c b/mm/compaction.c index b2977a5d659a..47f717fa4233 100644 --- a/mm/compaction.c +++ b/mm/compaction.c @@ -349,7 +349,8 @@ static isolate_migrate_t isolate_migratepages(struct zone *zone, } /* Try isolate the page */ - if (__isolate_lru_page(page, ISOLATE_BOTH, 0) != 0) + if (__isolate_lru_page(page, + ISOLATE_ACTIVE|ISOLATE_INACTIVE, 0) != 0) continue; VM_BUG_ON(PageTransCompound(page)); diff --git a/mm/memcontrol.c b/mm/memcontrol.c index 3508777837c7..2d5755544afe 100644 --- a/mm/memcontrol.c +++ b/mm/memcontrol.c @@ -1185,7 +1185,8 @@ mem_cgroup_get_reclaim_stat_from_page(struct page *page) unsigned long mem_cgroup_isolate_pages(unsigned long nr_to_scan, struct list_head *dst, unsigned long *scanned, int order, - int mode, struct zone *z, + isolate_mode_t mode, + struct zone *z, struct mem_cgroup *mem_cont, int active, int file) { diff --git a/mm/vmscan.c b/mm/vmscan.c index 9fdfce7ba403..ec6dbcb976d1 100644 --- a/mm/vmscan.c +++ b/mm/vmscan.c @@ -1012,23 +1012,27 @@ keep_lumpy: * * returns 0 on success, -ve errno on failure. */ -int __isolate_lru_page(struct page *page, int mode, int file) +int __isolate_lru_page(struct page *page, isolate_mode_t mode, int file) { + bool all_lru_mode; int ret = -EINVAL; /* Only take pages on the LRU. */ if (!PageLRU(page)) return ret; + all_lru_mode = (mode & (ISOLATE_ACTIVE|ISOLATE_INACTIVE)) == + (ISOLATE_ACTIVE|ISOLATE_INACTIVE); + /* * When checking the active state, we need to be sure we are * dealing with comparible boolean values. Take the logical not * of each. */ - if (mode != ISOLATE_BOTH && (!PageActive(page) != !mode)) + if (!all_lru_mode && !PageActive(page) != !(mode & ISOLATE_ACTIVE)) return ret; - if (mode != ISOLATE_BOTH && page_is_file_cache(page) != file) + if (!all_lru_mode && !!page_is_file_cache(page) != file) return ret; /* @@ -1076,7 +1080,8 @@ int __isolate_lru_page(struct page *page, int mode, int file) */ static unsigned long isolate_lru_pages(unsigned long nr_to_scan, struct list_head *src, struct list_head *dst, - unsigned long *scanned, int order, int mode, int file) + unsigned long *scanned, int order, isolate_mode_t mode, + int file) { unsigned long nr_taken = 0; unsigned long nr_lumpy_taken = 0; @@ -1201,8 +1206,8 @@ static unsigned long isolate_lru_pages(unsigned long nr_to_scan, static unsigned long isolate_pages_global(unsigned long nr, struct list_head *dst, unsigned long *scanned, int order, - int mode, struct zone *z, - int active, int file) + isolate_mode_t mode, + struct zone *z, int active, int file) { int lru = LRU_BASE; if (active) @@ -1448,6 +1453,7 @@ shrink_inactive_list(unsigned long nr_to_scan, struct zone *zone, unsigned long nr_taken; unsigned long nr_anon; unsigned long nr_file; + isolate_mode_t reclaim_mode = ISOLATE_INACTIVE; while (unlikely(too_many_isolated(zone, file, sc))) { congestion_wait(BLK_RW_ASYNC, HZ/10); @@ -1458,15 +1464,15 @@ shrink_inactive_list(unsigned long nr_to_scan, struct zone *zone, } set_reclaim_mode(priority, sc, false); + if (sc->reclaim_mode & RECLAIM_MODE_LUMPYRECLAIM) + reclaim_mode |= ISOLATE_ACTIVE; + lru_add_drain(); spin_lock_irq(&zone->lru_lock); if (scanning_global_lru(sc)) { - nr_taken = isolate_pages_global(nr_to_scan, - &page_list, &nr_scanned, sc->order, - sc->reclaim_mode & RECLAIM_MODE_LUMPYRECLAIM ? - ISOLATE_BOTH : ISOLATE_INACTIVE, - zone, 0, file); + nr_taken = isolate_pages_global(nr_to_scan, &page_list, + &nr_scanned, sc->order, reclaim_mode, zone, 0, file); zone->pages_scanned += nr_scanned; if (current_is_kswapd()) __count_zone_vm_events(PGSCAN_KSWAPD, zone, @@ -1475,12 +1481,9 @@ shrink_inactive_list(unsigned long nr_to_scan, struct zone *zone, __count_zone_vm_events(PGSCAN_DIRECT, zone, nr_scanned); } else { - nr_taken = mem_cgroup_isolate_pages(nr_to_scan, - &page_list, &nr_scanned, sc->order, - sc->reclaim_mode & RECLAIM_MODE_LUMPYRECLAIM ? - ISOLATE_BOTH : ISOLATE_INACTIVE, - zone, sc->mem_cgroup, - 0, file); + nr_taken = mem_cgroup_isolate_pages(nr_to_scan, &page_list, + &nr_scanned, sc->order, reclaim_mode, zone, + sc->mem_cgroup, 0, file); /* * mem_cgroup_isolate_pages() keeps track of * scanned pages on its own. -- cgit v1.2.3 From 39deaf8585152f1a35c1676d3d7dc6ae0fb65967 Mon Sep 17 00:00:00 2001 From: Minchan Kim Date: Mon, 31 Oct 2011 17:06:51 -0700 Subject: mm: compaction: make isolate_lru_page() filter-aware In async mode, compaction doesn't migrate dirty or writeback pages. So, it's meaningless to pick the page and re-add it to lru list. Of course, when we isolate the page in compaction, the page might be dirty or writeback but when we try to migrate the page, the page would be not dirty, writeback. So it could be migrated. But it's very unlikely as isolate and migration cycle is much faster than writeout. So, this patch helps cpu overhead and prevent unnecessary LRU churning. Signed-off-by: Minchan Kim Acked-by: Johannes Weiner Reviewed-by: KAMEZAWA Hiroyuki Reviewed-by: KOSAKI Motohiro Acked-by: Mel Gorman Acked-by: Rik van Riel Reviewed-by: Michal Hocko Cc: Andrea Arcangeli Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- include/linux/mmzone.h | 2 ++ mm/compaction.c | 7 +++++-- mm/vmscan.c | 3 +++ 3 files changed, 10 insertions(+), 2 deletions(-) (limited to 'mm') diff --git a/include/linux/mmzone.h b/include/linux/mmzone.h index 436ce6e7a446..80da968798ea 100644 --- a/include/linux/mmzone.h +++ b/include/linux/mmzone.h @@ -168,6 +168,8 @@ static inline int is_unevictable_lru(enum lru_list l) #define ISOLATE_INACTIVE ((__force isolate_mode_t)0x1) /* Isolate active pages */ #define ISOLATE_ACTIVE ((__force isolate_mode_t)0x2) +/* Isolate clean file */ +#define ISOLATE_CLEAN ((__force isolate_mode_t)0x4) /* LRU Isolation modes. */ typedef unsigned __bitwise__ isolate_mode_t; diff --git a/mm/compaction.c b/mm/compaction.c index 47f717fa4233..a0e420207ebf 100644 --- a/mm/compaction.c +++ b/mm/compaction.c @@ -261,6 +261,7 @@ static isolate_migrate_t isolate_migratepages(struct zone *zone, unsigned long last_pageblock_nr = 0, pageblock_nr; unsigned long nr_scanned = 0, nr_isolated = 0; struct list_head *migratelist = &cc->migratepages; + isolate_mode_t mode = ISOLATE_ACTIVE|ISOLATE_INACTIVE; /* Do not scan outside zone boundaries */ low_pfn = max(cc->migrate_pfn, zone->zone_start_pfn); @@ -348,9 +349,11 @@ static isolate_migrate_t isolate_migratepages(struct zone *zone, continue; } + if (!cc->sync) + mode |= ISOLATE_CLEAN; + /* Try isolate the page */ - if (__isolate_lru_page(page, - ISOLATE_ACTIVE|ISOLATE_INACTIVE, 0) != 0) + if (__isolate_lru_page(page, mode, 0) != 0) continue; VM_BUG_ON(PageTransCompound(page)); diff --git a/mm/vmscan.c b/mm/vmscan.c index ec6dbcb976d1..c007e78d7078 100644 --- a/mm/vmscan.c +++ b/mm/vmscan.c @@ -1045,6 +1045,9 @@ int __isolate_lru_page(struct page *page, isolate_mode_t mode, int file) ret = -EBUSY; + if ((mode & ISOLATE_CLEAN) && (PageDirty(page) || PageWriteback(page))) + return ret; + if (likely(get_page_unless_zero(page))) { /* * Be careful not to clear PageLRU until after we're -- cgit v1.2.3 From f80c0673610e36ae29d63e3297175e22f70dde5f Mon Sep 17 00:00:00 2001 From: Minchan Kim Date: Mon, 31 Oct 2011 17:06:55 -0700 Subject: mm: zone_reclaim: make isolate_lru_page() filter-aware In __zone_reclaim case, we don't want to shrink mapped page. Nonetheless, we have isolated mapped page and re-add it into LRU's head. It's unnecessary CPU overhead and makes LRU churning. Of course, when we isolate the page, the page might be mapped but when we try to migrate the page, the page would be not mapped. So it could be migrated. But race is rare and although it happens, it's no big deal. Signed-off-by: Minchan Kim Acked-by: Johannes Weiner Reviewed-by: KAMEZAWA Hiroyuki Reviewed-by: KOSAKI Motohiro Reviewed-by: Michal Hocko Cc: Mel Gorman Cc: Rik van Riel Cc: Andrea Arcangeli Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- include/linux/mmzone.h | 2 ++ mm/vmscan.c | 20 ++++++++++++++++++-- 2 files changed, 20 insertions(+), 2 deletions(-) (limited to 'mm') diff --git a/include/linux/mmzone.h b/include/linux/mmzone.h index 80da968798ea..ec57779c5a57 100644 --- a/include/linux/mmzone.h +++ b/include/linux/mmzone.h @@ -170,6 +170,8 @@ static inline int is_unevictable_lru(enum lru_list l) #define ISOLATE_ACTIVE ((__force isolate_mode_t)0x2) /* Isolate clean file */ #define ISOLATE_CLEAN ((__force isolate_mode_t)0x4) +/* Isolate unmapped file */ +#define ISOLATE_UNMAPPED ((__force isolate_mode_t)0x8) /* LRU Isolation modes. */ typedef unsigned __bitwise__ isolate_mode_t; diff --git a/mm/vmscan.c b/mm/vmscan.c index c007e78d7078..b68a9342d5a3 100644 --- a/mm/vmscan.c +++ b/mm/vmscan.c @@ -1048,6 +1048,9 @@ int __isolate_lru_page(struct page *page, isolate_mode_t mode, int file) if ((mode & ISOLATE_CLEAN) && (PageDirty(page) || PageWriteback(page))) return ret; + if ((mode & ISOLATE_UNMAPPED) && page_mapped(page)) + return ret; + if (likely(get_page_unless_zero(page))) { /* * Be careful not to clear PageLRU until after we're @@ -1471,6 +1474,12 @@ shrink_inactive_list(unsigned long nr_to_scan, struct zone *zone, reclaim_mode |= ISOLATE_ACTIVE; lru_add_drain(); + + if (!sc->may_unmap) + reclaim_mode |= ISOLATE_UNMAPPED; + if (!sc->may_writepage) + reclaim_mode |= ISOLATE_CLEAN; + spin_lock_irq(&zone->lru_lock); if (scanning_global_lru(sc)) { @@ -1588,19 +1597,26 @@ static void shrink_active_list(unsigned long nr_pages, struct zone *zone, struct page *page; struct zone_reclaim_stat *reclaim_stat = get_reclaim_stat(zone, sc); unsigned long nr_rotated = 0; + isolate_mode_t reclaim_mode = ISOLATE_ACTIVE; lru_add_drain(); + + if (!sc->may_unmap) + reclaim_mode |= ISOLATE_UNMAPPED; + if (!sc->may_writepage) + reclaim_mode |= ISOLATE_CLEAN; + spin_lock_irq(&zone->lru_lock); if (scanning_global_lru(sc)) { nr_taken = isolate_pages_global(nr_pages, &l_hold, &pgscanned, sc->order, - ISOLATE_ACTIVE, zone, + reclaim_mode, zone, 1, file); zone->pages_scanned += pgscanned; } else { nr_taken = mem_cgroup_isolate_pages(nr_pages, &l_hold, &pgscanned, sc->order, - ISOLATE_ACTIVE, zone, + reclaim_mode, zone, sc->mem_cgroup, 1, file); /* * mem_cgroup_isolate_pages() keeps track of -- cgit v1.2.3 From 0dabec93de633a87adfbbe1d800a4c56cd19d73b Mon Sep 17 00:00:00 2001 From: Minchan Kim Date: Mon, 31 Oct 2011 17:06:57 -0700 Subject: mm: migration: clean up unmap_and_move() unmap_and_move() is one a big messy function. Clean it up. Signed-off-by: Minchan Kim Reviewed-by: KOSAKI Motohiro Cc: Johannes Weiner Cc: KAMEZAWA Hiroyuki Cc: Mel Gorman Cc: Rik van Riel Cc: Michal Hocko Cc: Andrea Arcangeli Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- mm/migrate.c | 75 ++++++++++++++++++++++++++++++++---------------------------- 1 file changed, 40 insertions(+), 35 deletions(-) (limited to 'mm') diff --git a/mm/migrate.c b/mm/migrate.c index 14d0a6a632f6..33358f878111 100644 --- a/mm/migrate.c +++ b/mm/migrate.c @@ -621,38 +621,18 @@ static int move_to_new_page(struct page *newpage, struct page *page, return rc; } -/* - * Obtain the lock on page, remove all ptes and migrate the page - * to the newly allocated page in newpage. - */ -static int unmap_and_move(new_page_t get_new_page, unsigned long private, - struct page *page, int force, bool offlining, bool sync) +static int __unmap_and_move(struct page *page, struct page *newpage, + int force, bool offlining, bool sync) { - int rc = 0; - int *result = NULL; - struct page *newpage = get_new_page(page, private, &result); + int rc = -EAGAIN; int remap_swapcache = 1; int charge = 0; struct mem_cgroup *mem; struct anon_vma *anon_vma = NULL; - if (!newpage) - return -ENOMEM; - - if (page_count(page) == 1) { - /* page was freed from under us. So we are done. */ - goto move_newpage; - } - if (unlikely(PageTransHuge(page))) - if (unlikely(split_huge_page(page))) - goto move_newpage; - - /* prepare cgroup just returns 0 or -ENOMEM */ - rc = -EAGAIN; - if (!trylock_page(page)) { if (!force || !sync) - goto move_newpage; + goto out; /* * It's not safe for direct compaction to call lock_page. @@ -668,7 +648,7 @@ static int unmap_and_move(new_page_t get_new_page, unsigned long private, * altogether. */ if (current->flags & PF_MEMALLOC) - goto move_newpage; + goto out; lock_page(page); } @@ -785,27 +765,52 @@ uncharge: mem_cgroup_end_migration(mem, page, newpage, rc == 0); unlock: unlock_page(page); +out: + return rc; +} -move_newpage: +/* + * Obtain the lock on page, remove all ptes and migrate the page + * to the newly allocated page in newpage. + */ +static int unmap_and_move(new_page_t get_new_page, unsigned long private, + struct page *page, int force, bool offlining, bool sync) +{ + int rc = 0; + int *result = NULL; + struct page *newpage = get_new_page(page, private, &result); + + if (!newpage) + return -ENOMEM; + + if (page_count(page) == 1) { + /* page was freed from under us. So we are done. */ + goto out; + } + + if (unlikely(PageTransHuge(page))) + if (unlikely(split_huge_page(page))) + goto out; + + rc = __unmap_and_move(page, newpage, force, offlining, sync); +out: if (rc != -EAGAIN) { - /* - * A page that has been migrated has all references - * removed and will be freed. A page that has not been - * migrated will have kepts its references and be - * restored. - */ - list_del(&page->lru); + /* + * A page that has been migrated has all references + * removed and will be freed. A page that has not been + * migrated will have kepts its references and be + * restored. + */ + list_del(&page->lru); dec_zone_page_state(page, NR_ISOLATED_ANON + page_is_file_cache(page)); putback_lru_page(page); } - /* * Move the new page to the LRU. If migration was not successful * then this will free the page. */ putback_lru_page(newpage); - if (result) { if (rc) *result = rc; -- cgit v1.2.3 From 3da367c3e5fca71d4e778fa565d9b098d5518f4a Mon Sep 17 00:00:00 2001 From: Shaohua Li Date: Mon, 31 Oct 2011 17:07:03 -0700 Subject: vmscan: add block plug for page reclaim per-task block plug can reduce block queue lock contention and increase request merge. Currently page reclaim doesn't support it. I originally thought page reclaim doesn't need it, because kswapd thread count is limited and file cache write is done at flusher mostly. When I test a workload with heavy swap in a 4-node machine, each CPU is doing direct page reclaim and swap. This causes block queue lock contention. In my test, without below patch, the CPU utilization is about 2% ~ 7%. With the patch, the CPU utilization is about 1% ~ 3%. Disk throughput isn't changed. This should improve normal kswapd write and file cache write too (increase request merge for example), but might not be so obvious as I explain above. Signed-off-by: Shaohua Li Cc: Jens Axboe Cc: Minchan Kim Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- mm/vmscan.c | 3 +++ 1 file changed, 3 insertions(+) (limited to 'mm') diff --git a/mm/vmscan.c b/mm/vmscan.c index b68a9342d5a3..b1520b077858 100644 --- a/mm/vmscan.c +++ b/mm/vmscan.c @@ -2005,12 +2005,14 @@ static void shrink_zone(int priority, struct zone *zone, enum lru_list l; unsigned long nr_reclaimed, nr_scanned; unsigned long nr_to_reclaim = sc->nr_to_reclaim; + struct blk_plug plug; restart: nr_reclaimed = 0; nr_scanned = sc->nr_scanned; get_scan_count(zone, sc, nr, priority); + blk_start_plug(&plug); while (nr[LRU_INACTIVE_ANON] || nr[LRU_ACTIVE_FILE] || nr[LRU_INACTIVE_FILE]) { for_each_evictable_lru(l) { @@ -2034,6 +2036,7 @@ restart: if (nr_reclaimed >= nr_to_reclaim && priority < DEF_PRIORITY) break; } + blk_finish_plug(&plug); sc->nr_reclaimed += nr_reclaimed; /* -- cgit v1.2.3 From d08c429b06d21bd2add88aea2cd1996f1b9b3bda Mon Sep 17 00:00:00 2001 From: Johannes Weiner Date: Mon, 31 Oct 2011 17:07:05 -0700 Subject: mm/page-writeback.c: document bdi_min_ratio Looks like someone got distracted after adding the comment characters. Signed-off-by: Johannes Weiner Acked-by: Peter Zijlstra Cc: Wu Fengguang Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- mm/page-writeback.c | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-) (limited to 'mm') diff --git a/mm/page-writeback.c b/mm/page-writeback.c index 0e309cd1b5b9..793e9874de51 100644 --- a/mm/page-writeback.c +++ b/mm/page-writeback.c @@ -305,7 +305,9 @@ static unsigned long task_min_dirty_limit(unsigned long bdi_dirty) } /* - * + * bdi_min_ratio keeps the sum of the minimum dirty shares of all + * registered backing devices, which, for obvious reasons, can not + * exceed 100%. */ static unsigned int bdi_min_ratio; -- cgit v1.2.3 From f660daac474c6f7c2d710100e29b3276a6f4db0a Mon Sep 17 00:00:00 2001 From: David Rientjes Date: Mon, 31 Oct 2011 17:07:07 -0700 Subject: oom: thaw threads if oom killed thread is frozen before deferring If a thread has been oom killed and is frozen, thaw it before returning to the page allocator. Otherwise, it can stay frozen indefinitely and no memory will be freed. Signed-off-by: David Rientjes Reported-by: Konstantin Khlebnikov Cc: Oleg Nesterov Cc: KOSAKI Motohiro Cc: KAMEZAWA Hiroyuki Cc: "Rafael J. Wysocki" Acked-by: Michal Hocko Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- mm/oom_kill.c | 6 +++++- 1 file changed, 5 insertions(+), 1 deletion(-) (limited to 'mm') diff --git a/mm/oom_kill.c b/mm/oom_kill.c index 626303b52f3c..d897262068e2 100644 --- a/mm/oom_kill.c +++ b/mm/oom_kill.c @@ -32,6 +32,7 @@ #include #include #include +#include int sysctl_panic_on_oom; int sysctl_oom_kill_allocating_task; @@ -317,8 +318,11 @@ static struct task_struct *select_bad_process(unsigned int *ppoints, * blocked waiting for another task which itself is waiting * for memory. Is there a better alternative? */ - if (test_tsk_thread_flag(p, TIF_MEMDIE)) + if (test_tsk_thread_flag(p, TIF_MEMDIE)) { + if (unlikely(frozen(p))) + thaw_process(p); return ERR_PTR(-1UL); + } if (!p->mm) continue; -- cgit v1.2.3 From 7b0d44fa49b1dcfdcf4897f12ddd12ddeab1a9d7 Mon Sep 17 00:00:00 2001 From: David Rientjes Date: Mon, 31 Oct 2011 17:07:11 -0700 Subject: oom: avoid killing kthreads if they assume the oom killed thread's mm After selecting a task to kill, the oom killer iterates all processes and kills all other threads that share the same mm_struct in different thread groups. It would not otherwise be helpful to kill a thread if its memory would not be subsequently freed. A kernel thread, however, may assume a user thread's mm by using use_mm(). This is only temporary and should not result in sending a SIGKILL to that kthread. This patch ensures that only user threads and not kthreads are sent a SIGKILL if they share the same mm_struct as the oom killed task. Signed-off-by: David Rientjes Reviewed-by: Michal Hocko Reviewed-by: KOSAKI Motohiro Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- mm/oom_kill.c | 5 +++-- 1 file changed, 3 insertions(+), 2 deletions(-) (limited to 'mm') diff --git a/mm/oom_kill.c b/mm/oom_kill.c index d897262068e2..b0d8943bc9fd 100644 --- a/mm/oom_kill.c +++ b/mm/oom_kill.c @@ -439,7 +439,7 @@ static int oom_kill_task(struct task_struct *p, struct mem_cgroup *mem) task_unlock(p); /* - * Kill all processes sharing p->mm in other thread groups, if any. + * Kill all user processes sharing p->mm in other thread groups, if any. * They don't get access to memory reserves or a higher scheduler * priority, though, to avoid depletion of all memory or task * starvation. This prevents mm->mmap_sem livelock when an oom killed @@ -449,7 +449,8 @@ static int oom_kill_task(struct task_struct *p, struct mem_cgroup *mem) * signal. */ for_each_process(q) - if (q->mm == mm && !same_thread_group(q, p)) { + if (q->mm == mm && !same_thread_group(q, p) && + !(q->flags & PF_KTHREAD)) { task_lock(q); /* Protect ->comm from prctl() */ pr_err("Kill process %d (%s) sharing same memory\n", task_pid_nr(q), q->comm); -- cgit v1.2.3 From c9f01245b6a7d77d17deaa71af10f6aca14fa24e Mon Sep 17 00:00:00 2001 From: David Rientjes Date: Mon, 31 Oct 2011 17:07:15 -0700 Subject: oom: remove oom_disable_count This removes mm->oom_disable_count entirely since it's unnecessary and currently buggy. The counter was intended to be per-process but it's currently decremented in the exit path for each thread that exits, causing it to underflow. The count was originally intended to prevent oom killing threads that share memory with threads that cannot be killed since it doesn't lead to future memory freeing. The counter could be fixed to represent all threads sharing the same mm, but it's better to remove the count since: - it is possible that the OOM_DISABLE thread sharing memory with the victim is waiting on that thread to exit and will actually cause future memory freeing, and - there is no guarantee that a thread is disabled from oom killing just because another thread sharing its mm is oom disabled. Signed-off-by: David Rientjes Reported-by: Oleg Nesterov Reviewed-by: Oleg Nesterov Cc: Ying Han Cc: KOSAKI Motohiro Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- fs/exec.c | 4 ---- fs/proc/base.c | 13 ------------- include/linux/mm_types.h | 3 --- kernel/exit.c | 2 -- kernel/fork.c | 10 +--------- mm/oom_kill.c | 23 +++++------------------ 6 files changed, 6 insertions(+), 49 deletions(-) (limited to 'mm') diff --git a/fs/exec.c b/fs/exec.c index 25dcbe5fc356..36254645b7cc 100644 --- a/fs/exec.c +++ b/fs/exec.c @@ -841,10 +841,6 @@ static int exec_mmap(struct mm_struct *mm) tsk->mm = mm; tsk->active_mm = mm; activate_mm(active_mm, mm); - if (old_mm && tsk->signal->oom_score_adj == OOM_SCORE_ADJ_MIN) { - atomic_dec(&old_mm->oom_disable_count); - atomic_inc(&tsk->mm->oom_disable_count); - } task_unlock(tsk); arch_pick_mmap_layout(mm); if (old_mm) { diff --git a/fs/proc/base.c b/fs/proc/base.c index 5eb02069e1b8..8f0087e20e16 100644 --- a/fs/proc/base.c +++ b/fs/proc/base.c @@ -1107,13 +1107,6 @@ static ssize_t oom_adjust_write(struct file *file, const char __user *buf, goto err_sighand; } - if (oom_adjust != task->signal->oom_adj) { - if (oom_adjust == OOM_DISABLE) - atomic_inc(&task->mm->oom_disable_count); - if (task->signal->oom_adj == OOM_DISABLE) - atomic_dec(&task->mm->oom_disable_count); - } - /* * Warn that /proc/pid/oom_adj is deprecated, see * Documentation/feature-removal-schedule.txt. @@ -1215,12 +1208,6 @@ static ssize_t oom_score_adj_write(struct file *file, const char __user *buf, goto err_sighand; } - if (oom_score_adj != task->signal->oom_score_adj) { - if (oom_score_adj == OOM_SCORE_ADJ_MIN) - atomic_inc(&task->mm->oom_disable_count); - if (task->signal->oom_score_adj == OOM_SCORE_ADJ_MIN) - atomic_dec(&task->mm->oom_disable_count); - } task->signal->oom_score_adj = oom_score_adj; if (has_capability_noaudit(current, CAP_SYS_RESOURCE)) task->signal->oom_score_adj_min = oom_score_adj; diff --git a/include/linux/mm_types.h b/include/linux/mm_types.h index c93d00a6e95d..6456624aa964 100644 --- a/include/linux/mm_types.h +++ b/include/linux/mm_types.h @@ -336,9 +336,6 @@ struct mm_struct { unsigned int token_priority; unsigned int last_interval; - /* How many tasks sharing this mm are OOM_DISABLE */ - atomic_t oom_disable_count; - unsigned long flags; /* Must use atomic bitops to access the bits */ struct core_state *core_state; /* coredumping support */ diff --git a/kernel/exit.c b/kernel/exit.c index 2913b3509d42..d0b7d988f873 100644 --- a/kernel/exit.c +++ b/kernel/exit.c @@ -681,8 +681,6 @@ static void exit_mm(struct task_struct * tsk) enter_lazy_tlb(mm, current); /* We don't want this task to be frozen prematurely */ clear_freeze_flag(tsk); - if (tsk->signal->oom_score_adj == OOM_SCORE_ADJ_MIN) - atomic_dec(&mm->oom_disable_count); task_unlock(tsk); mm_update_next_owner(mm); mmput(mm); diff --git a/kernel/fork.c b/kernel/fork.c index 8e6b6f4fb272..70d76191afb9 100644 --- a/kernel/fork.c +++ b/kernel/fork.c @@ -501,7 +501,6 @@ static struct mm_struct *mm_init(struct mm_struct *mm, struct task_struct *p) mm->cached_hole_size = ~0UL; mm_init_aio(mm); mm_init_owner(mm, p); - atomic_set(&mm->oom_disable_count, 0); if (likely(!mm_alloc_pgd(mm))) { mm->def_flags = 0; @@ -816,8 +815,6 @@ good_mm: /* Initializing for Swap token stuff */ mm->token_priority = 0; mm->last_interval = 0; - if (tsk->signal->oom_score_adj == OOM_SCORE_ADJ_MIN) - atomic_inc(&mm->oom_disable_count); tsk->mm = mm; tsk->active_mm = mm; @@ -1391,13 +1388,8 @@ bad_fork_cleanup_io: bad_fork_cleanup_namespaces: exit_task_namespaces(p); bad_fork_cleanup_mm: - if (p->mm) { - task_lock(p); - if (p->signal->oom_score_adj == OOM_SCORE_ADJ_MIN) - atomic_dec(&p->mm->oom_disable_count); - task_unlock(p); + if (p->mm) mmput(p->mm); - } bad_fork_cleanup_signal: if (!(clone_flags & CLONE_THREAD)) free_signal_struct(p->signal); diff --git a/mm/oom_kill.c b/mm/oom_kill.c index b0d8943bc9fd..2b97e8f04607 100644 --- a/mm/oom_kill.c +++ b/mm/oom_kill.c @@ -54,13 +54,7 @@ int test_set_oom_score_adj(int new_val) spin_lock_irq(&sighand->siglock); old_val = current->signal->oom_score_adj; - if (new_val != old_val) { - if (new_val == OOM_SCORE_ADJ_MIN) - atomic_inc(¤t->mm->oom_disable_count); - else if (old_val == OOM_SCORE_ADJ_MIN) - atomic_dec(¤t->mm->oom_disable_count); - current->signal->oom_score_adj = new_val; - } + current->signal->oom_score_adj = new_val; spin_unlock_irq(&sighand->siglock); return old_val; @@ -172,16 +166,6 @@ unsigned int oom_badness(struct task_struct *p, struct mem_cgroup *mem, if (!p) return 0; - /* - * Shortcut check for a thread sharing p->mm that is OOM_SCORE_ADJ_MIN - * so the entire heuristic doesn't need to be executed for something - * that cannot be killed. - */ - if (atomic_read(&p->mm->oom_disable_count)) { - task_unlock(p); - return 0; - } - /* * The memory controller may have a limit of 0 bytes, so avoid a divide * by zero, if necessary. @@ -451,6 +435,9 @@ static int oom_kill_task(struct task_struct *p, struct mem_cgroup *mem) for_each_process(q) if (q->mm == mm && !same_thread_group(q, p) && !(q->flags & PF_KTHREAD)) { + if (q->signal->oom_score_adj == OOM_SCORE_ADJ_MIN) + continue; + task_lock(q); /* Protect ->comm from prctl() */ pr_err("Kill process %d (%s) sharing same memory\n", task_pid_nr(q), q->comm); @@ -727,7 +714,7 @@ void out_of_memory(struct zonelist *zonelist, gfp_t gfp_mask, read_lock(&tasklist_lock); if (sysctl_oom_kill_allocating_task && !oom_unkillable_task(current, NULL, nodemask) && - current->mm && !atomic_read(¤t->mm->oom_disable_count)) { + current->mm) { /* * oom_kill_process() needs tasklist_lock held. If it returns * non-zero, current could not be killed so we must fallback to -- cgit v1.2.3 From 43362a4977e37db46f86f7e6ab935f0006956632 Mon Sep 17 00:00:00 2001 From: David Rientjes Date: Mon, 31 Oct 2011 17:07:18 -0700 Subject: oom: fix race while temporarily setting current's oom_score_adj test_set_oom_score_adj() was introduced in 72788c385604 ("oom: replace PF_OOM_ORIGIN with toggling oom_score_adj") to temporarily elevate current's oom_score_adj for ksm and swapoff without requiring an additional per-process flag. Using that function to both set oom_score_adj to OOM_SCORE_ADJ_MAX and then reinstate the previous value is racy since it's possible that userspace can set the value to something else itself before the old value is reinstated. That results in userspace setting current's oom_score_adj to a different value and then the kernel immediately setting it back to its previous value without notification. To fix this, a new compare_swap_oom_score_adj() function is introduced with the same semantics as the compare and swap CAS instruction, or CMPXCHG on x86. It is used to reinstate the previous value of oom_score_adj if and only if the present value is the same as the old value. Signed-off-by: David Rientjes Cc: Oleg Nesterov Cc: Ying Han Cc: KOSAKI Motohiro Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- include/linux/oom.h | 1 + mm/ksm.c | 3 ++- mm/oom_kill.c | 19 +++++++++++++++++++ mm/swapfile.c | 2 +- 4 files changed, 23 insertions(+), 2 deletions(-) (limited to 'mm') diff --git a/include/linux/oom.h b/include/linux/oom.h index 13b7b02e599a..6f9d04a85336 100644 --- a/include/linux/oom.h +++ b/include/linux/oom.h @@ -40,6 +40,7 @@ enum oom_constraint { CONSTRAINT_MEMCG, }; +extern void compare_swap_oom_score_adj(int old_val, int new_val); extern int test_set_oom_score_adj(int new_val); extern unsigned int oom_badness(struct task_struct *p, struct mem_cgroup *mem, diff --git a/mm/ksm.c b/mm/ksm.c index 9a68b0cf0a1c..310544a379ae 100644 --- a/mm/ksm.c +++ b/mm/ksm.c @@ -1905,7 +1905,8 @@ static ssize_t run_store(struct kobject *kobj, struct kobj_attribute *attr, oom_score_adj = test_set_oom_score_adj(OOM_SCORE_ADJ_MAX); err = unmerge_and_remove_all_rmap_items(); - test_set_oom_score_adj(oom_score_adj); + compare_swap_oom_score_adj(OOM_SCORE_ADJ_MAX, + oom_score_adj); if (err) { ksm_run = KSM_RUN_STOP; count = err; diff --git a/mm/oom_kill.c b/mm/oom_kill.c index 2b97e8f04607..e916168b6e0a 100644 --- a/mm/oom_kill.c +++ b/mm/oom_kill.c @@ -39,6 +39,25 @@ int sysctl_oom_kill_allocating_task; int sysctl_oom_dump_tasks = 1; static DEFINE_SPINLOCK(zone_scan_lock); +/* + * compare_swap_oom_score_adj() - compare and swap current's oom_score_adj + * @old_val: old oom_score_adj for compare + * @new_val: new oom_score_adj for swap + * + * Sets the oom_score_adj value for current to @new_val iff its present value is + * @old_val. Usually used to reinstate a previous value to prevent racing with + * userspacing tuning the value in the interim. + */ +void compare_swap_oom_score_adj(int old_val, int new_val) +{ + struct sighand_struct *sighand = current->sighand; + + spin_lock_irq(&sighand->siglock); + if (current->signal->oom_score_adj == old_val) + current->signal->oom_score_adj = new_val; + spin_unlock_irq(&sighand->siglock); +} + /** * test_set_oom_score_adj() - set current's oom_score_adj and return old value * @new_val: new oom_score_adj value diff --git a/mm/swapfile.c b/mm/swapfile.c index 17bc224bce68..c9d654009125 100644 --- a/mm/swapfile.c +++ b/mm/swapfile.c @@ -1617,7 +1617,7 @@ SYSCALL_DEFINE1(swapoff, const char __user *, specialfile) oom_score_adj = test_set_oom_score_adj(OOM_SCORE_ADJ_MAX); err = try_to_unuse(type); - test_set_oom_score_adj(oom_score_adj); + compare_swap_oom_score_adj(OOM_SCORE_ADJ_MAX, oom_score_adj); if (err) { /* -- cgit v1.2.3 From 4f31888c104687078f8d88c2f11eca1080c88464 Mon Sep 17 00:00:00 2001 From: Dave Jones Date: Mon, 31 Oct 2011 17:07:24 -0700 Subject: mm: output a list of loaded modules when we hit bad_page() When we get a bad_page bug report, it's useful to see what modules the user had loaded. Signed-off-by: Dave Jones Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- mm/page_alloc.c | 1 + 1 file changed, 1 insertion(+) (limited to 'mm') diff --git a/mm/page_alloc.c b/mm/page_alloc.c index 6e8ecb6e021c..83a02052bce4 100644 --- a/mm/page_alloc.c +++ b/mm/page_alloc.c @@ -318,6 +318,7 @@ static void bad_page(struct page *page) current->comm, page_to_pfn(page)); dump_page(page); + print_modules(); dump_stack(); out: /* Leave bad fields for debug, except PageBuddy could make trouble */ -- cgit v1.2.3 From f11c0ca501af89fc07b0d9f17531ba3b68a4ef39 Mon Sep 17 00:00:00 2001 From: Johannes Weiner Date: Mon, 31 Oct 2011 17:07:27 -0700 Subject: mm: vmscan: drop nr_force_scan[] from get_scan_count The nr_force_scan[] tuple holds the effective scan numbers for anon and file pages in case the situation called for a forced scan and the regularly calculated scan numbers turned out zero. However, the effective scan number can always be assumed to be SWAP_CLUSTER_MAX right before the division into anon and file. The numerators and denominator are properly set up for all cases, be it force scan for just file, just anon, or both, to do the right thing. Signed-off-by: Johannes Weiner Reviewed-by: Minchan Kim Acked-by: KAMEZAWA Hiroyuki Reviewed-by: Michal Hocko Cc: Ying Han Cc: Balbir Singh Cc: KOSAKI Motohiro Cc: Daisuke Nishimura Acked-by: Mel Gorman Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- mm/vmscan.c | 36 ++++++++++++------------------------ 1 file changed, 12 insertions(+), 24 deletions(-) (limited to 'mm') diff --git a/mm/vmscan.c b/mm/vmscan.c index b1520b077858..d29b2bdb9e03 100644 --- a/mm/vmscan.c +++ b/mm/vmscan.c @@ -1817,12 +1817,19 @@ static void get_scan_count(struct zone *zone, struct scan_control *sc, enum lru_list l; int noswap = 0; bool force_scan = false; - unsigned long nr_force_scan[2]; - /* kswapd does zone balancing and needs to scan this zone */ + /* + * If the zone or memcg is small, nr[l] can be 0. This + * results in no scanning on this priority and a potential + * priority drop. Global direct reclaim can go to the next + * zone and tends to have no problems. Global kswapd is for + * zone balancing and it needs to scan a minimum amount. When + * reclaiming for a memcg, a priority drop can cause high + * latencies, so it's better to scan a minimum amount there as + * well. + */ if (scanning_global_lru(sc) && current_is_kswapd()) force_scan = true; - /* memcg may have small limit and need to avoid priority drop */ if (!scanning_global_lru(sc)) force_scan = true; @@ -1832,8 +1839,6 @@ static void get_scan_count(struct zone *zone, struct scan_control *sc, fraction[0] = 0; fraction[1] = 1; denominator = 1; - nr_force_scan[0] = 0; - nr_force_scan[1] = SWAP_CLUSTER_MAX; goto out; } @@ -1850,8 +1855,6 @@ static void get_scan_count(struct zone *zone, struct scan_control *sc, fraction[0] = 1; fraction[1] = 0; denominator = 1; - nr_force_scan[0] = SWAP_CLUSTER_MAX; - nr_force_scan[1] = 0; goto out; } } @@ -1900,11 +1903,6 @@ static void get_scan_count(struct zone *zone, struct scan_control *sc, fraction[0] = ap; fraction[1] = fp; denominator = ap + fp + 1; - if (force_scan) { - unsigned long scan = SWAP_CLUSTER_MAX; - nr_force_scan[0] = div64_u64(scan * ap, denominator); - nr_force_scan[1] = div64_u64(scan * fp, denominator); - } out: for_each_evictable_lru(l) { int file = is_file_lru(l); @@ -1913,20 +1911,10 @@ out: scan = zone_nr_lru_pages(zone, sc, l); if (priority || noswap) { scan >>= priority; + if (!scan && force_scan) + scan = SWAP_CLUSTER_MAX; scan = div64_u64(scan * fraction[file], denominator); } - - /* - * If zone is small or memcg is small, nr[l] can be 0. - * This results no-scan on this priority and priority drop down. - * For global direct reclaim, it can visit next zone and tend - * not to have problems. For global kswapd, it's for zone - * balancing and it need to scan a small amounts. When using - * memcg, priority drop can cause big latency. So, it's better - * to scan small amount. See may_noscan above. - */ - if (!scan && force_scan) - scan = nr_force_scan[file]; nr[l] = scan; } } -- cgit v1.2.3 From ee72886d8ed5d9de3fa0ed3b99a7ca7702576a96 Mon Sep 17 00:00:00 2001 From: Mel Gorman Date: Mon, 31 Oct 2011 17:07:38 -0700 Subject: mm: vmscan: do not writeback filesystem pages in direct reclaim Testing from the XFS folk revealed that there is still too much I/O from the end of the LRU in kswapd. Previously it was considered acceptable by VM people for a small number of pages to be written back from reclaim with testing generally showing about 0.3% of pages reclaimed were written back (higher if memory was low). That writing back a small number of pages is ok has been heavily disputed for quite some time and Dave Chinner explained it well; It doesn't have to be a very high number to be a problem. IO is orders of magnitude slower than the CPU time it takes to flush a page, so the cost of making a bad flush decision is very high. And single page writeback from the LRU is almost always a bad flush decision. To complicate matters, filesystems respond very differently to requests from reclaim according to Christoph Hellwig; xfs tries to write it back if the requester is kswapd ext4 ignores the request if it's a delayed allocation btrfs ignores the request As a result, each filesystem has different performance characteristics when under memory pressure and there are many pages being dirtied. In some cases, the request is ignored entirely so the VM cannot depend on the IO being dispatched. The objective of this series is to reduce writing of filesystem-backed pages from reclaim, play nicely with writeback that is already in progress and throttle reclaim appropriately when writeback pages are encountered. The assumption is that the flushers will always write pages faster than if reclaim issues the IO. A secondary goal is to avoid the problem whereby direct reclaim splices two potentially deep call stacks together. There is a potential new problem as reclaim has less control over how long before a page in a particularly zone or container is cleaned and direct reclaimers depend on kswapd or flusher threads to do the necessary work. However, as filesystems sometimes ignore direct reclaim requests already, it is not expected to be a serious issue. Patch 1 disables writeback of filesystem pages from direct reclaim entirely. Anonymous pages are still written. Patch 2 removes dead code in lumpy reclaim as it is no longer able to synchronously write pages. This hurts lumpy reclaim but there is an expectation that compaction is used for hugepage allocations these days and lumpy reclaim's days are numbered. Patches 3-4 add warnings to XFS and ext4 if called from direct reclaim. With patch 1, this "never happens" and is intended to catch regressions in this logic in the future. Patch 5 disables writeback of filesystem pages from kswapd unless the priority is raised to the point where kswapd is considered to be in trouble. Patch 6 throttles reclaimers if too many dirty pages are being encountered and the zones or backing devices are congested. Patch 7 invalidates dirty pages found at the end of the LRU so they are reclaimed quickly after being written back rather than waiting for a reclaimer to find them I consider this series to be orthogonal to the writeback work but it is worth noting that the writeback work affects the viability of patch 8 in particular. I tested this on ext4 and xfs using fs_mark, a simple writeback test based on dd and a micro benchmark that does a streaming write to a large mapping (exercises use-once LRU logic) followed by streaming writes to a mix of anonymous and file-backed mappings. The command line for fs_mark when botted with 512M looked something like ./fs_mark -d /tmp/fsmark-2676 -D 100 -N 150 -n 150 -L 25 -t 1 -S0 -s 10485760 The number of files was adjusted depending on the amount of available memory so that the files created was about 3xRAM. For multiple threads, the -d switch is specified multiple times. The test machine is x86-64 with an older generation of AMD processor with 4 cores. The underlying storage was 4 disks configured as RAID-0 as this was the best configuration of storage I had available. Swap is on a separate disk. Dirty ratio was tuned to 40% instead of the default of 20%. Testing was run with and without monitors to both verify that the patches were operating as expected and that any performance gain was real and not due to interference from monitors. Here is a summary of results based on testing XFS. 512M1P-xfs Files/s mean 32.69 ( 0.00%) 34.44 ( 5.08%) 512M1P-xfs Elapsed Time fsmark 51.41 48.29 512M1P-xfs Elapsed Time simple-wb 114.09 108.61 512M1P-xfs Elapsed Time mmap-strm 113.46 109.34 512M1P-xfs Kswapd efficiency fsmark 62% 63% 512M1P-xfs Kswapd efficiency simple-wb 56% 61% 512M1P-xfs Kswapd efficiency mmap-strm 44% 42% 512M-xfs Files/s mean 30.78 ( 0.00%) 35.94 (14.36%) 512M-xfs Elapsed Time fsmark 56.08 48.90 512M-xfs Elapsed Time simple-wb 112.22 98.13 512M-xfs Elapsed Time mmap-strm 219.15 196.67 512M-xfs Kswapd efficiency fsmark 54% 56% 512M-xfs Kswapd efficiency simple-wb 54% 55% 512M-xfs Kswapd efficiency mmap-strm 45% 44% 512M-4X-xfs Files/s mean 30.31 ( 0.00%) 33.33 ( 9.06%) 512M-4X-xfs Elapsed Time fsmark 63.26 55.88 512M-4X-xfs Elapsed Time simple-wb 100.90 90.25 512M-4X-xfs Elapsed Time mmap-strm 261.73 255.38 512M-4X-xfs Kswapd efficiency fsmark 49% 50% 512M-4X-xfs Kswapd efficiency simple-wb 54% 56% 512M-4X-xfs Kswapd efficiency mmap-strm 37% 36% 512M-16X-xfs Files/s mean 60.89 ( 0.00%) 65.22 ( 6.64%) 512M-16X-xfs Elapsed Time fsmark 67.47 58.25 512M-16X-xfs Elapsed Time simple-wb 103.22 90.89 512M-16X-xfs Elapsed Time mmap-strm 237.09 198.82 512M-16X-xfs Kswapd efficiency fsmark 45% 46% 512M-16X-xfs Kswapd efficiency simple-wb 53% 55% 512M-16X-xfs Kswapd efficiency mmap-strm 33% 33% Up until 512-4X, the FSmark improvements were statistically significant. For the 4X and 16X tests the results were within standard deviations but just barely. The time to completion for all tests is improved which is an important result. In general, kswapd efficiency is not affected by skipping dirty pages. 1024M1P-xfs Files/s mean 39.09 ( 0.00%) 41.15 ( 5.01%) 1024M1P-xfs Elapsed Time fsmark 84.14 80.41 1024M1P-xfs Elapsed Time simple-wb 210.77 184.78 1024M1P-xfs Elapsed Time mmap-strm 162.00 160.34 1024M1P-xfs Kswapd efficiency fsmark 69% 75% 1024M1P-xfs Kswapd efficiency simple-wb 71% 77% 1024M1P-xfs Kswapd efficiency mmap-strm 43% 44% 1024M-xfs Files/s mean 35.45 ( 0.00%) 37.00 ( 4.19%) 1024M-xfs Elapsed Time fsmark 94.59 91.00 1024M-xfs Elapsed Time simple-wb 229.84 195.08 1024M-xfs Elapsed Time mmap-strm 405.38 440.29 1024M-xfs Kswapd efficiency fsmark 79% 71% 1024M-xfs Kswapd efficiency simple-wb 74% 74% 1024M-xfs Kswapd efficiency mmap-strm 39% 42% 1024M-4X-xfs Files/s mean 32.63 ( 0.00%) 35.05 ( 6.90%) 1024M-4X-xfs Elapsed Time fsmark 103.33 97.74 1024M-4X-xfs Elapsed Time simple-wb 204.48 178.57 1024M-4X-xfs Elapsed Time mmap-strm 528.38 511.88 1024M-4X-xfs Kswapd efficiency fsmark 81% 70% 1024M-4X-xfs Kswapd efficiency simple-wb 73% 72% 1024M-4X-xfs Kswapd efficiency mmap-strm 39% 38% 1024M-16X-xfs Files/s mean 42.65 ( 0.00%) 42.97 ( 0.74%) 1024M-16X-xfs Elapsed Time fsmark 103.11 99.11 1024M-16X-xfs Elapsed Time simple-wb 200.83 178.24 1024M-16X-xfs Elapsed Time mmap-strm 397.35 459.82 1024M-16X-xfs Kswapd efficiency fsmark 84% 69% 1024M-16X-xfs Kswapd efficiency simple-wb 74% 73% 1024M-16X-xfs Kswapd efficiency mmap-strm 39% 40% All FSMark tests up to 16X had statistically significant improvements. For the most part, tests are completing faster with the exception of the streaming writes to a mixture of anonymous and file-backed mappings which were slower in two cases In the cases where the mmap-strm tests were slower, there was more swapping due to dirty pages being skipped. The number of additional pages swapped is almost identical to the fewer number of pages written from reclaim. In other words, roughly the same number of pages were reclaimed but swapping was slower. As the test is a bit unrealistic and stresses memory heavily, the small shift is acceptable. 4608M1P-xfs Files/s mean 29.75 ( 0.00%) 30.96 ( 3.91%) 4608M1P-xfs Elapsed Time fsmark 512.01 492.15 4608M1P-xfs Elapsed Time simple-wb 618.18 566.24 4608M1P-xfs Elapsed Time mmap-strm 488.05 465.07 4608M1P-xfs Kswapd efficiency fsmark 93% 86% 4608M1P-xfs Kswapd efficiency simple-wb 88% 84% 4608M1P-xfs Kswapd efficiency mmap-strm 46% 45% 4608M-xfs Files/s mean 27.60 ( 0.00%) 28.85 ( 4.33%) 4608M-xfs Elapsed Time fsmark 555.96 532.34 4608M-xfs Elapsed Time simple-wb 659.72 571.85 4608M-xfs Elapsed Time mmap-strm 1082.57 1146.38 4608M-xfs Kswapd efficiency fsmark 89% 91% 4608M-xfs Kswapd efficiency simple-wb 88% 82% 4608M-xfs Kswapd efficiency mmap-strm 48% 46% 4608M-4X-xfs Files/s mean 26.00 ( 0.00%) 27.47 ( 5.35%) 4608M-4X-xfs Elapsed Time fsmark 592.91 564.00 4608M-4X-xfs Elapsed Time simple-wb 616.65 575.07 4608M-4X-xfs Elapsed Time mmap-strm 1773.02 1631.53 4608M-4X-xfs Kswapd efficiency fsmark 90% 94% 4608M-4X-xfs Kswapd efficiency simple-wb 87% 82% 4608M-4X-xfs Kswapd efficiency mmap-strm 43% 43% 4608M-16X-xfs Files/s mean 26.07 ( 0.00%) 26.42 ( 1.32%) 4608M-16X-xfs Elapsed Time fsmark 602.69 585.78 4608M-16X-xfs Elapsed Time simple-wb 606.60 573.81 4608M-16X-xfs Elapsed Time mmap-strm 1549.75 1441.86 4608M-16X-xfs Kswapd efficiency fsmark 98% 98% 4608M-16X-xfs Kswapd efficiency simple-wb 88% 82% 4608M-16X-xfs Kswapd efficiency mmap-strm 44% 42% Unlike the other tests, the fsmark results are not statistically significant but the min and max times are both improved and for the most part, tests completed faster. There are other indications that this is an improvement as well. For example, in the vast majority of cases, there were fewer pages scanned by direct reclaim implying in many cases that stalls due to direct reclaim are reduced. KSwapd is scanning more due to skipping dirty pages which is unfortunate but the CPU usage is still acceptable In an earlier set of tests, I used blktrace and in almost all cases throughput throughout the entire test was higher. However, I ended up discarding those results as recording blktrace data was too heavy for my liking. On a laptop, I plugged in a USB stick and ran a similar tests of tests using it as backing storage. A desktop environment was running and for the entire duration of the tests, firefox and gnome terminal were launching and exiting to vaguely simulate a user. 1024M-xfs Files/s mean 0.41 ( 0.00%) 0.44 ( 6.82%) 1024M-xfs Elapsed Time fsmark 2053.52 1641.03 1024M-xfs Elapsed Time simple-wb 1229.53 768.05 1024M-xfs Elapsed Time mmap-strm 4126.44 4597.03 1024M-xfs Kswapd efficiency fsmark 84% 85% 1024M-xfs Kswapd efficiency simple-wb 92% 81% 1024M-xfs Kswapd efficiency mmap-strm 60% 51% 1024M-xfs Avg wait ms fsmark 5404.53 4473.87 1024M-xfs Avg wait ms simple-wb 2541.35 1453.54 1024M-xfs Avg wait ms mmap-strm 3400.25 3852.53 The mmap-strm results were hurt because firefox launching had a tendency to push the test out of memory. On the postive side, firefox launched marginally faster with the patches applied. Time to completion for many tests was faster but more importantly - the "Avg wait" time as measured by iostat was far lower implying the system would be more responsive. It was also the case that "Avg wait ms" on the root filesystem was lower. I tested it manually and while the system felt slightly more responsive while copying data to a USB stick, it was marginal enough that it could be my imagination. This patch: do not writeback filesystem pages in direct reclaim. When kswapd is failing to keep zones above the min watermark, a process will enter direct reclaim in the same manner kswapd does. If a dirty page is encountered during the scan, this page is written to backing storage using mapping->writepage. This causes two problems. First, it can result in very deep call stacks, particularly if the target storage or filesystem are complex. Some filesystems ignore write requests from direct reclaim as a result. The second is that a single-page flush is inefficient in terms of IO. While there is an expectation that the elevator will merge requests, this does not always happen. Quoting Christoph Hellwig; The elevator has a relatively small window it can operate on, and can never fix up a bad large scale writeback pattern. This patch prevents direct reclaim writing back filesystem pages by checking if current is kswapd. Anonymous pages are still written to swap as there is not the equivalent of a flusher thread for anonymous pages. If the dirty pages cannot be written back, they are placed back on the LRU lists. There is now a direct dependency on dirty page balancing to prevent too many pages in the system being dirtied which would prevent reclaim making forward progress. Signed-off-by: Mel Gorman Reviewed-by: Minchan Kim Cc: Dave Chinner Cc: Christoph Hellwig Cc: Johannes Weiner Cc: Wu Fengguang Cc: Jan Kara Cc: Rik van Riel Cc: Mel Gorman Cc: Alex Elder Cc: Theodore Ts'o Cc: Chris Mason Cc: Dave Hansen Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- include/linux/mmzone.h | 1 + mm/vmscan.c | 9 +++++++++ mm/vmstat.c | 1 + 3 files changed, 11 insertions(+) (limited to 'mm') diff --git a/include/linux/mmzone.h b/include/linux/mmzone.h index ec57779c5a57..2c41b2c1943b 100644 --- a/include/linux/mmzone.h +++ b/include/linux/mmzone.h @@ -100,6 +100,7 @@ enum zone_stat_item { NR_UNSTABLE_NFS, /* NFS unstable pages */ NR_BOUNCE, NR_VMSCAN_WRITE, + NR_VMSCAN_WRITE_SKIP, NR_WRITEBACK_TEMP, /* Writeback using temporary buffers */ NR_ISOLATED_ANON, /* Temporary isolated pages from anon lru */ NR_ISOLATED_FILE, /* Temporary isolated pages from file lru */ diff --git a/mm/vmscan.c b/mm/vmscan.c index d29b2bdb9e03..10f9c59aed55 100644 --- a/mm/vmscan.c +++ b/mm/vmscan.c @@ -865,6 +865,15 @@ static unsigned long shrink_page_list(struct list_head *page_list, if (PageDirty(page)) { nr_dirty++; + /* + * Only kswapd can writeback filesystem pages to + * avoid risk of stack overflow + */ + if (page_is_file_cache(page) && !current_is_kswapd()) { + inc_zone_page_state(page, NR_VMSCAN_WRITE_SKIP); + goto keep_locked; + } + if (references == PAGEREF_RECLAIM_CLEAN) goto keep_locked; if (!may_enter_fs) diff --git a/mm/vmstat.c b/mm/vmstat.c index d52b13d28e8f..210bd8ff3a6e 100644 --- a/mm/vmstat.c +++ b/mm/vmstat.c @@ -702,6 +702,7 @@ const char * const vmstat_text[] = { "nr_unstable", "nr_bounce", "nr_vmscan_write", + "nr_vmscan_write_skip", "nr_writeback_temp", "nr_isolated_anon", "nr_isolated_file", -- cgit v1.2.3 From a18bba061c789f5815c3efc3c80e6ac269911964 Mon Sep 17 00:00:00 2001 From: Mel Gorman Date: Mon, 31 Oct 2011 17:07:42 -0700 Subject: mm: vmscan: remove dead code related to lumpy reclaim waiting on pages under writeback Lumpy reclaim worked with two passes - the first which queued pages for IO and the second which waited on writeback. As direct reclaim can no longer write pages there is some dead code. This patch removes it but direct reclaim will continue to wait on pages under writeback while in synchronous reclaim mode. Signed-off-by: Mel Gorman Cc: Dave Chinner Cc: Christoph Hellwig Cc: Johannes Weiner Cc: Wu Fengguang Cc: Jan Kara Cc: Minchan Kim Cc: Rik van Riel Cc: Mel Gorman Cc: Alex Elder Cc: Theodore Ts'o Cc: Chris Mason Cc: Dave Hansen Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- mm/vmscan.c | 21 +++++---------------- 1 file changed, 5 insertions(+), 16 deletions(-) (limited to 'mm') diff --git a/mm/vmscan.c b/mm/vmscan.c index 10f9c59aed55..5c596654bd37 100644 --- a/mm/vmscan.c +++ b/mm/vmscan.c @@ -495,15 +495,6 @@ static pageout_t pageout(struct page *page, struct address_space *mapping, return PAGE_ACTIVATE; } - /* - * Wait on writeback if requested to. This happens when - * direct reclaiming a large contiguous area and the - * first attempt to free a range of pages fails. - */ - if (PageWriteback(page) && - (sc->reclaim_mode & RECLAIM_MODE_SYNC)) - wait_on_page_writeback(page); - if (!PageWriteback(page)) { /* synchronous write or broken a_ops? */ ClearPageReclaim(page); @@ -804,12 +795,10 @@ static unsigned long shrink_page_list(struct list_head *page_list, if (PageWriteback(page)) { /* - * Synchronous reclaim is performed in two passes, - * first an asynchronous pass over the list to - * start parallel writeback, and a second synchronous - * pass to wait for the IO to complete. Wait here - * for any page for which writeback has already - * started. + * Synchronous reclaim cannot queue pages for + * writeback due to the possibility of stack overflow + * but if it encounters a page under writeback, wait + * for the IO to complete. */ if ((sc->reclaim_mode & RECLAIM_MODE_SYNC) && may_enter_fs) @@ -1414,7 +1403,7 @@ static noinline_for_stack void update_isolated_counts(struct zone *zone, } /* - * Returns true if the caller should wait to clean dirty/writeback pages. + * Returns true if a direct reclaim should wait on pages under writeback. * * If we are direct reclaiming for contiguous pages and we do not reclaim * everything in the list, try again and wait for writeback IO to complete. -- cgit v1.2.3 From f84f6e2b0868f198f97a32ba503d6f9f319a249a Mon Sep 17 00:00:00 2001 From: Mel Gorman Date: Mon, 31 Oct 2011 17:07:51 -0700 Subject: mm: vmscan: do not writeback filesystem pages in kswapd except in high priority It is preferable that no dirty pages are dispatched for cleaning from the page reclaim path. At normal priorities, this patch prevents kswapd writing pages. However, page reclaim does have a requirement that pages be freed in a particular zone. If it is failing to make sufficient progress (reclaiming < SWAP_CLUSTER_MAX at any priority priority), the priority is raised to scan more pages. A priority of DEF_PRIORITY - 3 is considered to be the point where kswapd is getting into trouble reclaiming pages. If this priority is reached, kswapd will dispatch pages for writing. Signed-off-by: Mel Gorman Reviewed-by: Minchan Kim Cc: Dave Chinner Cc: Christoph Hellwig Cc: Johannes Weiner Cc: Wu Fengguang Cc: Jan Kara Cc: Rik van Riel Cc: Mel Gorman Cc: Alex Elder Cc: Theodore Ts'o Cc: Chris Mason Cc: Dave Hansen Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- mm/vmscan.c | 13 ++++++++----- 1 file changed, 8 insertions(+), 5 deletions(-) (limited to 'mm') diff --git a/mm/vmscan.c b/mm/vmscan.c index 5c596654bd37..15e3a29fdb23 100644 --- a/mm/vmscan.c +++ b/mm/vmscan.c @@ -750,7 +750,8 @@ static noinline_for_stack void free_page_list(struct list_head *free_pages) */ static unsigned long shrink_page_list(struct list_head *page_list, struct zone *zone, - struct scan_control *sc) + struct scan_control *sc, + int priority) { LIST_HEAD(ret_pages); LIST_HEAD(free_pages); @@ -856,9 +857,11 @@ static unsigned long shrink_page_list(struct list_head *page_list, /* * Only kswapd can writeback filesystem pages to - * avoid risk of stack overflow + * avoid risk of stack overflow but do not writeback + * unless under significant pressure. */ - if (page_is_file_cache(page) && !current_is_kswapd()) { + if (page_is_file_cache(page) && + (!current_is_kswapd() || priority >= DEF_PRIORITY - 2)) { inc_zone_page_state(page, NR_VMSCAN_WRITE_SKIP); goto keep_locked; } @@ -1509,12 +1512,12 @@ shrink_inactive_list(unsigned long nr_to_scan, struct zone *zone, spin_unlock_irq(&zone->lru_lock); - nr_reclaimed = shrink_page_list(&page_list, zone, sc); + nr_reclaimed = shrink_page_list(&page_list, zone, sc, priority); /* Check if we should syncronously wait for writeback */ if (should_reclaim_stall(nr_taken, nr_reclaimed, priority, sc)) { set_reclaim_mode(priority, sc, true); - nr_reclaimed += shrink_page_list(&page_list, zone, sc); + nr_reclaimed += shrink_page_list(&page_list, zone, sc, priority); } local_irq_disable(); -- cgit v1.2.3 From 92df3a723f84cdf8133560bbff950a7a99e92bc9 Mon Sep 17 00:00:00 2001 From: Mel Gorman Date: Mon, 31 Oct 2011 17:07:56 -0700 Subject: mm: vmscan: throttle reclaim if encountering too many dirty pages under writeback Workloads that are allocating frequently and writing files place a large number of dirty pages on the LRU. With use-once logic, it is possible for them to reach the end of the LRU quickly requiring the reclaimer to scan more to find clean pages. Ordinarily, processes that are dirtying memory will get throttled by dirty balancing but this is a global heuristic and does not take into account that LRUs are maintained on a per-zone basis. This can lead to a situation whereby reclaim is scanning heavily, skipping over a large number of pages under writeback and recycling them around the LRU consuming CPU. This patch checks how many of the number of pages isolated from the LRU were dirty and under writeback. If a percentage of them under writeback, the process will be throttled if a backing device or the zone is congested. Note that this applies whether it is anonymous or file-backed pages that are under writeback meaning that swapping is potentially throttled. This is intentional due to the fact if the swap device is congested, scanning more pages and dispatching more IO is not going to help matters. The percentage that must be in writeback depends on the priority. At default priority, all of them must be dirty. At DEF_PRIORITY-1, 50% of them must be, DEF_PRIORITY-2, 25% etc. i.e. as pressure increases the greater the likelihood the process will get throttled to allow the flusher threads to make some progress. Signed-off-by: Mel Gorman Reviewed-by: Minchan Kim Acked-by: Johannes Weiner Cc: Dave Chinner Cc: Christoph Hellwig Cc: Wu Fengguang Cc: Jan Kara Cc: Rik van Riel Cc: Mel Gorman Cc: Alex Elder Cc: Theodore Ts'o Cc: Chris Mason Cc: Dave Hansen Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- mm/vmscan.c | 42 +++++++++++++++++++++++++++++++++++++++--- 1 file changed, 39 insertions(+), 3 deletions(-) (limited to 'mm') diff --git a/mm/vmscan.c b/mm/vmscan.c index 15e3a29fdb23..7b0573f33a27 100644 --- a/mm/vmscan.c +++ b/mm/vmscan.c @@ -751,7 +751,9 @@ static noinline_for_stack void free_page_list(struct list_head *free_pages) static unsigned long shrink_page_list(struct list_head *page_list, struct zone *zone, struct scan_control *sc, - int priority) + int priority, + unsigned long *ret_nr_dirty, + unsigned long *ret_nr_writeback) { LIST_HEAD(ret_pages); LIST_HEAD(free_pages); @@ -759,6 +761,7 @@ static unsigned long shrink_page_list(struct list_head *page_list, unsigned long nr_dirty = 0; unsigned long nr_congested = 0; unsigned long nr_reclaimed = 0; + unsigned long nr_writeback = 0; cond_resched(); @@ -795,6 +798,7 @@ static unsigned long shrink_page_list(struct list_head *page_list, (PageSwapCache(page) && (sc->gfp_mask & __GFP_IO)); if (PageWriteback(page)) { + nr_writeback++; /* * Synchronous reclaim cannot queue pages for * writeback due to the possibility of stack overflow @@ -1000,6 +1004,8 @@ keep_lumpy: list_splice(&ret_pages, page_list); count_vm_events(PGACTIVATE, pgactivate); + *ret_nr_dirty += nr_dirty; + *ret_nr_writeback += nr_writeback; return nr_reclaimed; } @@ -1460,6 +1466,8 @@ shrink_inactive_list(unsigned long nr_to_scan, struct zone *zone, unsigned long nr_taken; unsigned long nr_anon; unsigned long nr_file; + unsigned long nr_dirty = 0; + unsigned long nr_writeback = 0; isolate_mode_t reclaim_mode = ISOLATE_INACTIVE; while (unlikely(too_many_isolated(zone, file, sc))) { @@ -1512,12 +1520,14 @@ shrink_inactive_list(unsigned long nr_to_scan, struct zone *zone, spin_unlock_irq(&zone->lru_lock); - nr_reclaimed = shrink_page_list(&page_list, zone, sc, priority); + nr_reclaimed = shrink_page_list(&page_list, zone, sc, priority, + &nr_dirty, &nr_writeback); /* Check if we should syncronously wait for writeback */ if (should_reclaim_stall(nr_taken, nr_reclaimed, priority, sc)) { set_reclaim_mode(priority, sc, true); - nr_reclaimed += shrink_page_list(&page_list, zone, sc, priority); + nr_reclaimed += shrink_page_list(&page_list, zone, sc, + priority, &nr_dirty, &nr_writeback); } local_irq_disable(); @@ -1527,6 +1537,32 @@ shrink_inactive_list(unsigned long nr_to_scan, struct zone *zone, putback_lru_pages(zone, sc, nr_anon, nr_file, &page_list); + /* + * If reclaim is isolating dirty pages under writeback, it implies + * that the long-lived page allocation rate is exceeding the page + * laundering rate. Either the global limits are not being effective + * at throttling processes due to the page distribution throughout + * zones or there is heavy usage of a slow backing device. The + * only option is to throttle from reclaim context which is not ideal + * as there is no guarantee the dirtying process is throttled in the + * same way balance_dirty_pages() manages. + * + * This scales the number of dirty pages that must be under writeback + * before throttling depending on priority. It is a simple backoff + * function that has the most effect in the range DEF_PRIORITY to + * DEF_PRIORITY-2 which is the priority reclaim is considered to be + * in trouble and reclaim is considered to be in trouble. + * + * DEF_PRIORITY 100% isolated pages must be PageWriteback to throttle + * DEF_PRIORITY-1 50% must be PageWriteback + * DEF_PRIORITY-2 25% must be PageWriteback, kswapd in trouble + * ... + * DEF_PRIORITY-6 For SWAP_CLUSTER_MAX isolated pages, throttle if any + * isolated page is PageWriteback + */ + if (nr_writeback && nr_writeback >= (nr_taken >> (DEF_PRIORITY-priority))) + wait_iff_congested(zone, BLK_RW_ASYNC, HZ/10); + trace_mm_vmscan_lru_shrink_inactive(zone->zone_pgdat->node_id, zone_idx(zone), nr_scanned, nr_reclaimed, -- cgit v1.2.3 From 49ea7eb65e7c5060807fb9312b1ad4c3eab82e2c Mon Sep 17 00:00:00 2001 From: Mel Gorman Date: Mon, 31 Oct 2011 17:07:59 -0700 Subject: mm: vmscan: immediately reclaim end-of-LRU dirty pages when writeback completes When direct reclaim encounters a dirty page, it gets recycled around the LRU for another cycle. This patch marks the page PageReclaim similar to deactivate_page() so that the page gets reclaimed almost immediately after the page gets cleaned. This is to avoid reclaiming clean pages that are younger than a dirty page encountered at the end of the LRU that might have been something like a use-once page. Signed-off-by: Mel Gorman Acked-by: Johannes Weiner Cc: Dave Chinner Cc: Christoph Hellwig Cc: Wu Fengguang Cc: Jan Kara Cc: Minchan Kim Cc: Rik van Riel Cc: Mel Gorman Cc: Alex Elder Cc: Theodore Ts'o Cc: Chris Mason Cc: Dave Hansen Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- include/linux/mmzone.h | 2 +- mm/vmscan.c | 10 +++++++++- mm/vmstat.c | 2 +- 3 files changed, 11 insertions(+), 3 deletions(-) (limited to 'mm') diff --git a/include/linux/mmzone.h b/include/linux/mmzone.h index 2c41b2c1943b..188cb2ffe8db 100644 --- a/include/linux/mmzone.h +++ b/include/linux/mmzone.h @@ -100,7 +100,7 @@ enum zone_stat_item { NR_UNSTABLE_NFS, /* NFS unstable pages */ NR_BOUNCE, NR_VMSCAN_WRITE, - NR_VMSCAN_WRITE_SKIP, + NR_VMSCAN_IMMEDIATE, /* Prioritise for reclaim when writeback ends */ NR_WRITEBACK_TEMP, /* Writeback using temporary buffers */ NR_ISOLATED_ANON, /* Temporary isolated pages from anon lru */ NR_ISOLATED_FILE, /* Temporary isolated pages from file lru */ diff --git a/mm/vmscan.c b/mm/vmscan.c index 7b0573f33a27..a297603d35bc 100644 --- a/mm/vmscan.c +++ b/mm/vmscan.c @@ -866,7 +866,15 @@ static unsigned long shrink_page_list(struct list_head *page_list, */ if (page_is_file_cache(page) && (!current_is_kswapd() || priority >= DEF_PRIORITY - 2)) { - inc_zone_page_state(page, NR_VMSCAN_WRITE_SKIP); + /* + * Immediately reclaim when written back. + * Similar in principal to deactivate_page() + * except we already have the page isolated + * and know it's dirty + */ + inc_zone_page_state(page, NR_VMSCAN_IMMEDIATE); + SetPageReclaim(page); + goto keep_locked; } diff --git a/mm/vmstat.c b/mm/vmstat.c index 210bd8ff3a6e..56e529a40517 100644 --- a/mm/vmstat.c +++ b/mm/vmstat.c @@ -702,7 +702,7 @@ const char * const vmstat_text[] = { "nr_unstable", "nr_bounce", "nr_vmscan_write", - "nr_vmscan_write_skip", + "nr_vmscan_immediate_reclaim", "nr_writeback_temp", "nr_isolated_anon", "nr_isolated_file", -- cgit v1.2.3 From 16fb951237c2b0b28037b992ee44e7ee401c30d1 Mon Sep 17 00:00:00 2001 From: Shaohua Li Date: Mon, 31 Oct 2011 17:08:02 -0700 Subject: vmscan: count pages into balanced for zone with good watermark It's possible a zone watermark is ok when entering the balance_pgdat() loop, while the zone is within the requested classzone_idx. Count pages from this zone into `balanced'. In this way, we can skip shrinking zones too much for high order allocation. Signed-off-by: Shaohua Li Acked-by: Mel Gorman Reviewed-by: Minchan Kim Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- mm/vmscan.c | 2 ++ 1 file changed, 2 insertions(+) (limited to 'mm') diff --git a/mm/vmscan.c b/mm/vmscan.c index a297603d35bc..77ee24fc891a 100644 --- a/mm/vmscan.c +++ b/mm/vmscan.c @@ -2748,6 +2748,8 @@ out: /* If balanced, clear the congested flag */ zone_clear_flag(zone, ZONE_CONGESTED); + if (i <= *classzone_idx) + balanced += zone->present_pages; } } -- cgit v1.2.3 From 77311139f364d7f71fc9ba88f59fd90e60205007 Mon Sep 17 00:00:00 2001 From: Akinobu Mita Date: Mon, 31 Oct 2011 17:08:05 -0700 Subject: mm/debug-pagealloc.c: use plain __ratelimit() instead of printk_ratelimit() printk_ratelimit() should not be used, because it shares ratelimiting state with all other unrelated printk_ratelimit() callsites. Signed-off-by: Akinobu Mita Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- mm/debug-pagealloc.c | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-) (limited to 'mm') diff --git a/mm/debug-pagealloc.c b/mm/debug-pagealloc.c index a1e3324de2b5..a4b6d707a31f 100644 --- a/mm/debug-pagealloc.c +++ b/mm/debug-pagealloc.c @@ -2,6 +2,7 @@ #include #include #include +#include static inline void set_page_poison(struct page *page) { @@ -59,6 +60,7 @@ static bool single_bit_flip(unsigned char a, unsigned char b) static void check_poison_mem(unsigned char *mem, size_t bytes) { + static DEFINE_RATELIMIT_STATE(ratelimit, 5 * HZ, 10); unsigned char *start; unsigned char *end; @@ -74,7 +76,7 @@ static void check_poison_mem(unsigned char *mem, size_t bytes) break; } - if (!printk_ratelimit()) + if (!__ratelimit(&ratelimit)) return; else if (start == end && single_bit_flip(*start, PAGE_POISON)) printk(KERN_ERR "pagealloc: single bit error\n"); -- cgit v1.2.3 From 798248206b59acc6e1238c778281419c041891a7 Mon Sep 17 00:00:00 2001 From: Akinobu Mita Date: Mon, 31 Oct 2011 17:08:07 -0700 Subject: lib/string.c: introduce memchr_inv() memchr_inv() is mainly used to check whether the whole buffer is filled with just a specified byte. The function name and prototype are stolen from logfs and the implementation is from SLUB. Signed-off-by: Akinobu Mita Acked-by: Christoph Lameter Acked-by: Pekka Enberg Cc: Matt Mackall Acked-by: Joern Engel Cc: Marcin Slusarz Cc: Eric Dumazet Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- fs/logfs/logfs.h | 1 - fs/logfs/super.c | 22 -------------------- include/linux/string.h | 1 + lib/string.c | 54 ++++++++++++++++++++++++++++++++++++++++++++++++++ mm/slub.c | 47 ++----------------------------------------- 5 files changed, 57 insertions(+), 68 deletions(-) (limited to 'mm') diff --git a/fs/logfs/logfs.h b/fs/logfs/logfs.h index f22d108bfa5d..398ecff6e548 100644 --- a/fs/logfs/logfs.h +++ b/fs/logfs/logfs.h @@ -618,7 +618,6 @@ static inline int logfs_buf_recover(struct logfs_area *area, u64 ofs, struct page *emergency_read_begin(struct address_space *mapping, pgoff_t index); void emergency_read_end(struct page *page); void logfs_crash_dump(struct super_block *sb); -void *memchr_inv(const void *s, int c, size_t n); int logfs_statfs(struct dentry *dentry, struct kstatfs *stats); int logfs_check_ds(struct logfs_disk_super *ds); int logfs_write_sb(struct super_block *sb); diff --git a/fs/logfs/super.c b/fs/logfs/super.c index ce03a182c771..f2697e4df109 100644 --- a/fs/logfs/super.c +++ b/fs/logfs/super.c @@ -90,28 +90,6 @@ void logfs_crash_dump(struct super_block *sb) dump_segfile(sb); } -/* - * TODO: move to lib/string.c - */ -/** - * memchr_inv - Find a character in an area of memory. - * @s: The memory area - * @c: The byte to search for - * @n: The size of the area. - * - * returns the address of the first character other than @c, or %NULL - * if the whole buffer contains just @c. - */ -void *memchr_inv(const void *s, int c, size_t n) -{ - const unsigned char *p = s; - while (n-- != 0) - if ((unsigned char)c != *p++) - return (void *)(p - 1); - - return NULL; -} - /* * FIXME: There should be a reserve for root, similar to ext2. */ diff --git a/include/linux/string.h b/include/linux/string.h index a176db2f2c85..e033564f10ba 100644 --- a/include/linux/string.h +++ b/include/linux/string.h @@ -114,6 +114,7 @@ extern int memcmp(const void *,const void *,__kernel_size_t); #ifndef __HAVE_ARCH_MEMCHR extern void * memchr(const void *,int,__kernel_size_t); #endif +void *memchr_inv(const void *s, int c, size_t n); extern char *kstrdup(const char *s, gfp_t gfp); extern char *kstrndup(const char *s, size_t len, gfp_t gfp); diff --git a/lib/string.c b/lib/string.c index 01fad9b203e1..11df54325fb8 100644 --- a/lib/string.c +++ b/lib/string.c @@ -756,3 +756,57 @@ void *memchr(const void *s, int c, size_t n) } EXPORT_SYMBOL(memchr); #endif + +static void *check_bytes8(const u8 *start, u8 value, unsigned int bytes) +{ + while (bytes) { + if (*start != value) + return (void *)start; + start++; + bytes--; + } + return NULL; +} + +/** + * memchr_inv - Find an unmatching character in an area of memory. + * @start: The memory area + * @c: Find a character other than c + * @bytes: The size of the area. + * + * returns the address of the first character other than @c, or %NULL + * if the whole buffer contains just @c. + */ +void *memchr_inv(const void *start, int c, size_t bytes) +{ + u8 value = c; + u64 value64; + unsigned int words, prefix; + + if (bytes <= 16) + return check_bytes8(start, value, bytes); + + value64 = value | value << 8 | value << 16 | value << 24; + value64 = (value64 & 0xffffffff) | value64 << 32; + prefix = 8 - ((unsigned long)start) % 8; + + if (prefix) { + u8 *r = check_bytes8(start, value, prefix); + if (r) + return r; + start += prefix; + bytes -= prefix; + } + + words = bytes / 8; + + while (words) { + if (*(u64 *)start != value64) + return check_bytes8(start, value, 8); + start += 8; + words--; + } + + return check_bytes8(start, value, bytes % 8); +} +EXPORT_SYMBOL(memchr_inv); diff --git a/mm/slub.c b/mm/slub.c index 95215aa6a75e..7d2a996c307e 100644 --- a/mm/slub.c +++ b/mm/slub.c @@ -655,49 +655,6 @@ static void init_object(struct kmem_cache *s, void *object, u8 val) memset(p + s->objsize, val, s->inuse - s->objsize); } -static u8 *check_bytes8(u8 *start, u8 value, unsigned int bytes) -{ - while (bytes) { - if (*start != value) - return start; - start++; - bytes--; - } - return NULL; -} - -static u8 *check_bytes(u8 *start, u8 value, unsigned int bytes) -{ - u64 value64; - unsigned int words, prefix; - - if (bytes <= 16) - return check_bytes8(start, value, bytes); - - value64 = value | value << 8 | value << 16 | value << 24; - value64 = (value64 & 0xffffffff) | value64 << 32; - prefix = 8 - ((unsigned long)start) % 8; - - if (prefix) { - u8 *r = check_bytes8(start, value, prefix); - if (r) - return r; - start += prefix; - bytes -= prefix; - } - - words = bytes / 8; - - while (words) { - if (*(u64 *)start != value64) - return check_bytes8(start, value, 8); - start += 8; - words--; - } - - return check_bytes8(start, value, bytes % 8); -} - static void restore_bytes(struct kmem_cache *s, char *message, u8 data, void *from, void *to) { @@ -712,7 +669,7 @@ static int check_bytes_and_report(struct kmem_cache *s, struct page *page, u8 *fault; u8 *end; - fault = check_bytes(start, value, bytes); + fault = memchr_inv(start, value, bytes); if (!fault) return 1; @@ -805,7 +762,7 @@ static int slab_pad_check(struct kmem_cache *s, struct page *page) if (!remainder) return 1; - fault = check_bytes(end - remainder, POISON_INUSE, remainder); + fault = memchr_inv(end - remainder, POISON_INUSE, remainder); if (!fault) return 1; while (end > fault && end[-1] == POISON_INUSE) -- cgit v1.2.3 From 8c5fb8eadde41f67c61a7ac2d3246dab87bf7020 Mon Sep 17 00:00:00 2001 From: Akinobu Mita Date: Mon, 31 Oct 2011 17:08:10 -0700 Subject: mm/debug-pagealloc.c: use memchr_inv Use newly introduced memchr_inv() for page verification. Signed-off-by: Akinobu Mita Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- mm/debug-pagealloc.c | 8 +++----- 1 file changed, 3 insertions(+), 5 deletions(-) (limited to 'mm') diff --git a/mm/debug-pagealloc.c b/mm/debug-pagealloc.c index a4b6d707a31f..2618933efdb3 100644 --- a/mm/debug-pagealloc.c +++ b/mm/debug-pagealloc.c @@ -1,4 +1,5 @@ #include +#include #include #include #include @@ -64,11 +65,8 @@ static void check_poison_mem(unsigned char *mem, size_t bytes) unsigned char *start; unsigned char *end; - for (start = mem; start < mem + bytes; start++) { - if (*start != PAGE_POISON) - break; - } - if (start == mem + bytes) + start = memchr_inv(mem, PAGE_POISON, bytes); + if (!start) return; for (end = mem + bytes - 1; end > start; end--) { -- cgit v1.2.3 From f5252e009d5b87071a919221e4f6624184005368 Mon Sep 17 00:00:00 2001 From: Mitsuo Hayasaka Date: Mon, 31 Oct 2011 17:08:13 -0700 Subject: mm: avoid null pointer access in vm_struct via /proc/vmallocinfo The /proc/vmallocinfo shows information about vmalloc allocations in vmlist that is a linklist of vm_struct. It, however, may access pages field of vm_struct where a page was not allocated. This results in a null pointer access and leads to a kernel panic. Why this happens: In __vmalloc_node_range() called from vmalloc(), newly allocated vm_struct is added to vmlist at __get_vm_area_node() and then, some fields of vm_struct such as nr_pages and pages are set at __vmalloc_area_node(). In other words, it is added to vmlist before it is fully initialized. At the same time, when the /proc/vmallocinfo is read, it accesses the pages field of vm_struct according to the nr_pages field at show_numa_info(). Thus, a null pointer access happens. The patch adds the newly allocated vm_struct to the vmlist *after* it is fully initialized. So, it can avoid accessing the pages field with unallocated page when show_numa_info() is called. Signed-off-by: Mitsuo Hayasaka Cc: Andrew Morton Cc: David Rientjes Cc: Namhyung Kim Cc: "Paul E. McKenney" Cc: Jeremy Fitzhardinge Cc: Cc: Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- include/linux/vmalloc.h | 1 + mm/vmalloc.c | 65 ++++++++++++++++++++++++++++++++++++------------- 2 files changed, 49 insertions(+), 17 deletions(-) (limited to 'mm') diff --git a/include/linux/vmalloc.h b/include/linux/vmalloc.h index 9332e52ea8c2..687fb11e2010 100644 --- a/include/linux/vmalloc.h +++ b/include/linux/vmalloc.h @@ -13,6 +13,7 @@ struct vm_area_struct; /* vma defining user mapping in mm_types.h */ #define VM_MAP 0x00000004 /* vmap()ed pages */ #define VM_USERMAP 0x00000008 /* suitable for remap_vmalloc_range */ #define VM_VPAGES 0x00000010 /* buffer for pages was vmalloc'ed */ +#define VM_UNLIST 0x00000020 /* vm_struct is not listed in vmlist */ /* bits [20..32] reserved for arch specific ioremap internals */ /* diff --git a/mm/vmalloc.c b/mm/vmalloc.c index 5016f19e1661..56faf3163ee2 100644 --- a/mm/vmalloc.c +++ b/mm/vmalloc.c @@ -1253,18 +1253,22 @@ EXPORT_SYMBOL_GPL(map_vm_area); DEFINE_RWLOCK(vmlist_lock); struct vm_struct *vmlist; -static void insert_vmalloc_vm(struct vm_struct *vm, struct vmap_area *va, +static void setup_vmalloc_vm(struct vm_struct *vm, struct vmap_area *va, unsigned long flags, void *caller) { - struct vm_struct *tmp, **p; - vm->flags = flags; vm->addr = (void *)va->va_start; vm->size = va->va_end - va->va_start; vm->caller = caller; va->private = vm; va->flags |= VM_VM_AREA; +} + +static void insert_vmalloc_vmlist(struct vm_struct *vm) +{ + struct vm_struct *tmp, **p; + vm->flags &= ~VM_UNLIST; write_lock(&vmlist_lock); for (p = &vmlist; (tmp = *p) != NULL; p = &tmp->next) { if (tmp->addr >= vm->addr) @@ -1275,6 +1279,13 @@ static void insert_vmalloc_vm(struct vm_struct *vm, struct vmap_area *va, write_unlock(&vmlist_lock); } +static void insert_vmalloc_vm(struct vm_struct *vm, struct vmap_area *va, + unsigned long flags, void *caller) +{ + setup_vmalloc_vm(vm, va, flags, caller); + insert_vmalloc_vmlist(vm); +} + static struct vm_struct *__get_vm_area_node(unsigned long size, unsigned long align, unsigned long flags, unsigned long start, unsigned long end, int node, gfp_t gfp_mask, void *caller) @@ -1313,7 +1324,18 @@ static struct vm_struct *__get_vm_area_node(unsigned long size, return NULL; } - insert_vmalloc_vm(area, va, flags, caller); + /* + * When this function is called from __vmalloc_node_range, + * we do not add vm_struct to vmlist here to avoid + * accessing uninitialized members of vm_struct such as + * pages and nr_pages fields. They will be set later. + * To distinguish it from others, we use a VM_UNLIST flag. + */ + if (flags & VM_UNLIST) + setup_vmalloc_vm(area, va, flags, caller); + else + insert_vmalloc_vm(area, va, flags, caller); + return area; } @@ -1381,17 +1403,20 @@ struct vm_struct *remove_vm_area(const void *addr) va = find_vmap_area((unsigned long)addr); if (va && va->flags & VM_VM_AREA) { struct vm_struct *vm = va->private; - struct vm_struct *tmp, **p; - /* - * remove from list and disallow access to this vm_struct - * before unmap. (address range confliction is maintained by - * vmap.) - */ - write_lock(&vmlist_lock); - for (p = &vmlist; (tmp = *p) != vm; p = &tmp->next) - ; - *p = tmp->next; - write_unlock(&vmlist_lock); + + if (!(vm->flags & VM_UNLIST)) { + struct vm_struct *tmp, **p; + /* + * remove from list and disallow access to + * this vm_struct before unmap. (address range + * confliction is maintained by vmap.) + */ + write_lock(&vmlist_lock); + for (p = &vmlist; (tmp = *p) != vm; p = &tmp->next) + ; + *p = tmp->next; + write_unlock(&vmlist_lock); + } vmap_debug_free_range(va->va_start, va->va_end); free_unmap_vmap_area(va); @@ -1602,14 +1627,20 @@ void *__vmalloc_node_range(unsigned long size, unsigned long align, if (!size || (size >> PAGE_SHIFT) > totalram_pages) return NULL; - area = __get_vm_area_node(size, align, VM_ALLOC, start, end, node, - gfp_mask, caller); + area = __get_vm_area_node(size, align, VM_ALLOC | VM_UNLIST, + start, end, node, gfp_mask, caller); if (!area) return NULL; addr = __vmalloc_area_node(area, gfp_mask, prot, node, caller); + /* + * In this function, newly allocated vm_struct is not added + * to vmlist at __get_vm_area_node(). so, it is added here. + */ + insert_vmalloc_vmlist(area); + /* * A ref_count = 3 is needed because the vm_struct and vmap_area * structures allocated in the __get_vm_area_node() function contain -- cgit v1.2.3 From 0a93ebef698b08ed04af0d7d913bab8aedfdc253 Mon Sep 17 00:00:00 2001 From: Sam Ravnborg Date: Mon, 31 Oct 2011 17:08:16 -0700 Subject: memblock: add memblock_start_of_DRAM() SPARC32 require access to the start address. Add a new helper memblock_start_of_DRAM() to give access to the address of the first memblock - which contains the lowest address. The awkward name was chosen to match the already present memblock_end_of_DRAM(). Signed-off-by: Sam Ravnborg Cc: "David S. Miller" Cc: Yinghai Lu Acked-by: Tejun Heo Cc: "H. Peter Anvin" Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- include/linux/memblock.h | 1 + mm/memblock.c | 6 ++++++ 2 files changed, 7 insertions(+) (limited to 'mm') diff --git a/include/linux/memblock.h b/include/linux/memblock.h index 7525e38c434d..e6b843e16e81 100644 --- a/include/linux/memblock.h +++ b/include/linux/memblock.h @@ -80,6 +80,7 @@ extern phys_addr_t __memblock_alloc_base(phys_addr_t size, phys_addr_t align, phys_addr_t max_addr); extern phys_addr_t memblock_phys_mem_size(void); +extern phys_addr_t memblock_start_of_DRAM(void); extern phys_addr_t memblock_end_of_DRAM(void); extern void memblock_enforce_memory_limit(phys_addr_t memory_limit); extern int memblock_is_memory(phys_addr_t addr); diff --git a/mm/memblock.c b/mm/memblock.c index ccbf97339592..b7ed63633581 100644 --- a/mm/memblock.c +++ b/mm/memblock.c @@ -626,6 +626,12 @@ phys_addr_t __init memblock_phys_mem_size(void) return memblock.memory_size; } +/* lowest address */ +phys_addr_t __init_memblock memblock_start_of_DRAM(void) +{ + return memblock.memory.regions[0].base; +} + phys_addr_t __init_memblock memblock_end_of_DRAM(void) { int idx = memblock.memory.cnt - 1; -- cgit v1.2.3 From 6661672053aee709d93f5dbd7887c789364c11d4 Mon Sep 17 00:00:00 2001 From: Sam Ravnborg Date: Mon, 31 Oct 2011 17:08:20 -0700 Subject: memblock: add NO_BOOTMEM config symbol With the NO_BOOTMEM symbol added architectures may now use the following syntax to tell that they do not need bootmem: select NO_BOOTMEM This is much more convinient than adding a new kconfig symbol which was otherwise required. Adding this symbol does not conflict with the architctures that already define their own symbol. Signed-off-by: Sam Ravnborg Cc: Yinghai Lu Acked-by: Tejun Heo Cc: "H. Peter Anvin" Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- mm/Kconfig | 3 +++ 1 file changed, 3 insertions(+) (limited to 'mm') diff --git a/mm/Kconfig b/mm/Kconfig index f2f1ca19ed53..011b110365c8 100644 --- a/mm/Kconfig +++ b/mm/Kconfig @@ -131,6 +131,9 @@ config SPARSEMEM_VMEMMAP config HAVE_MEMBLOCK boolean +config NO_BOOTMEM + boolean + # eventually, we can have this option just 'select SPARSEMEM' config MEMORY_HOTPLUG bool "Allow for memory hot-add" -- cgit v1.2.3 From ebed48460be5abd86d9a24fa7c66378e58109f30 Mon Sep 17 00:00:00 2001 From: Andrea Arcangeli Date: Mon, 31 Oct 2011 17:08:22 -0700 Subject: mremap: check for overflow using deltas Using "- 1" relies on the old_end to be page aligned and PAGE_SIZE > 1, those are reasonable requirements but the check remains obscure and it looks more like an off by one error than an overflow check. This I feel will improve readability. Signed-off-by: Andrea Arcangeli Acked-by: Johannes Weiner Acked-by: Mel Gorman Acked-by: Rik van Riel Cc: Hugh Dickins Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- mm/mremap.c | 5 +++-- 1 file changed, 3 insertions(+), 2 deletions(-) (limited to 'mm') diff --git a/mm/mremap.c b/mm/mremap.c index 506fa44403df..195e866568e0 100644 --- a/mm/mremap.c +++ b/mm/mremap.c @@ -141,9 +141,10 @@ unsigned long move_page_tables(struct vm_area_struct *vma, for (; old_addr < old_end; old_addr += extent, new_addr += extent) { cond_resched(); next = (old_addr + PMD_SIZE) & PMD_MASK; - if (next - 1 > old_end) - next = old_end; + /* even if next overflowed, extent below will be ok */ extent = next - old_addr; + if (extent > old_end - old_addr) + extent = old_end - old_addr; old_pmd = get_old_pmd(vma->vm_mm, old_addr); if (!old_pmd) continue; -- cgit v1.2.3 From 7b6efc2bc4f19952b25ebf9b236e5ac43cd386c2 Mon Sep 17 00:00:00 2001 From: Andrea Arcangeli Date: Mon, 31 Oct 2011 17:08:26 -0700 Subject: mremap: avoid sending one IPI per page This replaces ptep_clear_flush() with ptep_get_and_clear() and a single flush_tlb_range() at the end of the loop, to avoid sending one IPI for each page. The mmu_notifier_invalidate_range_start/end section is enlarged accordingly but this is not going to fundamentally change things. It was more by accident that the region under mremap was for the most part still available for secondary MMUs: the primary MMU was never allowed to reliably access that region for the duration of the mremap (modulo trapping SIGSEGV on the old address range which sounds unpractical and flakey). If users wants secondary MMUs not to lose access to a large region under mremap they should reduce the mremap size accordingly in userland and run multiple calls. Overall this will run faster so it's actually going to reduce the time the region is under mremap for the primary MMU which should provide a net benefit to apps. For KVM this is a noop because the guest physical memory is never mremapped, there's just no point it ever moving it while guest runs. One target of this optimization is JVM GC (so unrelated to the mmu notifier logic). Signed-off-by: Andrea Arcangeli Acked-by: Johannes Weiner Acked-by: Mel Gorman Acked-by: Rik van Riel Cc: Hugh Dickins Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- mm/mremap.c | 15 +++++++++------ 1 file changed, 9 insertions(+), 6 deletions(-) (limited to 'mm') diff --git a/mm/mremap.c b/mm/mremap.c index 195e866568e0..a184f3732e1e 100644 --- a/mm/mremap.c +++ b/mm/mremap.c @@ -80,11 +80,7 @@ static void move_ptes(struct vm_area_struct *vma, pmd_t *old_pmd, struct mm_struct *mm = vma->vm_mm; pte_t *old_pte, *new_pte, pte; spinlock_t *old_ptl, *new_ptl; - unsigned long old_start; - old_start = old_addr; - mmu_notifier_invalidate_range_start(vma->vm_mm, - old_start, old_end); if (vma->vm_file) { /* * Subtle point from Rajesh Venkatasubramanian: before @@ -111,7 +107,7 @@ static void move_ptes(struct vm_area_struct *vma, pmd_t *old_pmd, new_pte++, new_addr += PAGE_SIZE) { if (pte_none(*old_pte)) continue; - pte = ptep_clear_flush(vma, old_addr, old_pte); + pte = ptep_get_and_clear(mm, old_addr, old_pte); pte = move_pte(pte, new_vma->vm_page_prot, old_addr, new_addr); set_pte_at(mm, new_addr, new_pte, pte); } @@ -123,7 +119,6 @@ static void move_ptes(struct vm_area_struct *vma, pmd_t *old_pmd, pte_unmap_unlock(old_pte - 1, old_ptl); if (mapping) mutex_unlock(&mapping->i_mmap_mutex); - mmu_notifier_invalidate_range_end(vma->vm_mm, old_start, old_end); } #define LATENCY_LIMIT (64 * PAGE_SIZE) @@ -134,10 +129,13 @@ unsigned long move_page_tables(struct vm_area_struct *vma, { unsigned long extent, next, old_end; pmd_t *old_pmd, *new_pmd; + bool need_flush = false; old_end = old_addr + len; flush_cache_range(vma, old_addr, old_end); + mmu_notifier_invalidate_range_start(vma->vm_mm, old_addr, old_end); + for (; old_addr < old_end; old_addr += extent, new_addr += extent) { cond_resched(); next = (old_addr + PMD_SIZE) & PMD_MASK; @@ -158,7 +156,12 @@ unsigned long move_page_tables(struct vm_area_struct *vma, extent = LATENCY_LIMIT; move_ptes(vma, old_pmd, old_addr, old_addr + extent, new_vma, new_pmd, new_addr); + need_flush = true; } + if (likely(need_flush)) + flush_tlb_range(vma, old_end-len, old_addr); + + mmu_notifier_invalidate_range_end(vma->vm_mm, old_end-len, old_end); return len + old_addr - old_end; /* how much done */ } -- cgit v1.2.3 From 37a1c49a91ad55f917a399ef2174b5ebda4283f9 Mon Sep 17 00:00:00 2001 From: Andrea Arcangeli Date: Mon, 31 Oct 2011 17:08:30 -0700 Subject: thp: mremap support and TLB optimization This adds THP support to mremap (decreases the number of split_huge_page() calls). Here are also some benchmarks with a proggy like this: === #define _GNU_SOURCE #include #include #include #include #include #define SIZE (5UL*1024*1024*1024) int main() { static struct timeval oldstamp, newstamp; long diffsec; char *p, *p2, *p3, *p4; if (posix_memalign((void **)&p, 2*1024*1024, SIZE)) perror("memalign"), exit(1); if (posix_memalign((void **)&p2, 2*1024*1024, SIZE)) perror("memalign"), exit(1); if (posix_memalign((void **)&p3, 2*1024*1024, 4096)) perror("memalign"), exit(1); memset(p, 0xff, SIZE); memset(p2, 0xff, SIZE); memset(p3, 0x77, 4096); gettimeofday(&oldstamp, NULL); p4 = mremap(p, SIZE, SIZE, MREMAP_FIXED|MREMAP_MAYMOVE, p3); gettimeofday(&newstamp, NULL); diffsec = newstamp.tv_sec - oldstamp.tv_sec; diffsec = newstamp.tv_usec - oldstamp.tv_usec + 1000000 * diffsec; printf("usec %ld\n", diffsec); if (p == MAP_FAILED || p4 != p3) //if (p == MAP_FAILED) perror("mremap"), exit(1); if (memcmp(p4, p2, SIZE)) printf("mremap bug\n"), exit(1); printf("ok\n"); return 0; } === THP on Performance counter stats for './largepage13' (3 runs): 69195836 dTLB-loads ( +- 3.546% ) (scaled from 50.30%) 60708 dTLB-load-misses ( +- 11.776% ) (scaled from 52.62%) 676266476 dTLB-stores ( +- 5.654% ) (scaled from 69.54%) 29856 dTLB-store-misses ( +- 4.081% ) (scaled from 89.22%) 1055848782 iTLB-loads ( +- 4.526% ) (scaled from 80.18%) 8689 iTLB-load-misses ( +- 2.987% ) (scaled from 58.20%) 7.314454164 seconds time elapsed ( +- 0.023% ) THP off Performance counter stats for './largepage13' (3 runs): 1967379311 dTLB-loads ( +- 0.506% ) (scaled from 60.59%) 9238687 dTLB-load-misses ( +- 22.547% ) (scaled from 61.87%) 2014239444 dTLB-stores ( +- 0.692% ) (scaled from 60.40%) 3312335 dTLB-store-misses ( +- 7.304% ) (scaled from 67.60%) 6764372065 iTLB-loads ( +- 0.925% ) (scaled from 79.00%) 8202 iTLB-load-misses ( +- 0.475% ) (scaled from 70.55%) 9.693655243 seconds time elapsed ( +- 0.069% ) grep thp /proc/vmstat thp_fault_alloc 35849 thp_fault_fallback 0 thp_collapse_alloc 3 thp_collapse_alloc_failed 0 thp_split 0 thp_split 0 confirms no thp split despite plenty of hugepages allocated. The measurement of only the mremap time (so excluding the 3 long memset and final long 10GB memory accessing memcmp): THP on usec 14824 usec 14862 usec 14859 THP off usec 256416 usec 255981 usec 255847 With an older kernel without the mremap optimizations (the below patch optimizes the non THP version too). THP on usec 392107 usec 390237 usec 404124 THP off usec 444294 usec 445237 usec 445820 I guess with a threaded program that sends more IPI on large SMP it'd create an even larger difference. All debug options are off except DEBUG_VM to avoid skewing the results. The only problem for native 2M mremap like it happens above both the source and destination address must be 2M aligned or the hugepmd can't be moved without a split but that is an hardware limitation. [akpm@linux-foundation.org: coding-style nitpicking] Signed-off-by: Andrea Arcangeli Acked-by: Johannes Weiner Acked-by: Mel Gorman Acked-by: Rik van Riel Cc: Hugh Dickins Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- include/linux/huge_mm.h | 5 +++++ mm/huge_memory.c | 45 +++++++++++++++++++++++++++++++++++++++++++++ mm/mremap.c | 22 ++++++++++++++++++---- 3 files changed, 68 insertions(+), 4 deletions(-) (limited to 'mm') diff --git a/include/linux/huge_mm.h b/include/linux/huge_mm.h index 48c32ebf65a7..a9ace9c32507 100644 --- a/include/linux/huge_mm.h +++ b/include/linux/huge_mm.h @@ -22,6 +22,11 @@ extern int zap_huge_pmd(struct mmu_gather *tlb, extern int mincore_huge_pmd(struct vm_area_struct *vma, pmd_t *pmd, unsigned long addr, unsigned long end, unsigned char *vec); +extern int move_huge_pmd(struct vm_area_struct *vma, + struct vm_area_struct *new_vma, + unsigned long old_addr, + unsigned long new_addr, unsigned long old_end, + pmd_t *old_pmd, pmd_t *new_pmd); extern int change_huge_pmd(struct vm_area_struct *vma, pmd_t *pmd, unsigned long addr, pgprot_t newprot); diff --git a/mm/huge_memory.c b/mm/huge_memory.c index e2d1587be269..6b072bdccf81 100644 --- a/mm/huge_memory.c +++ b/mm/huge_memory.c @@ -1052,6 +1052,51 @@ int mincore_huge_pmd(struct vm_area_struct *vma, pmd_t *pmd, return ret; } +int move_huge_pmd(struct vm_area_struct *vma, struct vm_area_struct *new_vma, + unsigned long old_addr, + unsigned long new_addr, unsigned long old_end, + pmd_t *old_pmd, pmd_t *new_pmd) +{ + int ret = 0; + pmd_t pmd; + + struct mm_struct *mm = vma->vm_mm; + + if ((old_addr & ~HPAGE_PMD_MASK) || + (new_addr & ~HPAGE_PMD_MASK) || + old_end - old_addr < HPAGE_PMD_SIZE || + (new_vma->vm_flags & VM_NOHUGEPAGE)) + goto out; + + /* + * The destination pmd shouldn't be established, free_pgtables() + * should have release it. + */ + if (WARN_ON(!pmd_none(*new_pmd))) { + VM_BUG_ON(pmd_trans_huge(*new_pmd)); + goto out; + } + + spin_lock(&mm->page_table_lock); + if (likely(pmd_trans_huge(*old_pmd))) { + if (pmd_trans_splitting(*old_pmd)) { + spin_unlock(&mm->page_table_lock); + wait_split_huge_page(vma->anon_vma, old_pmd); + ret = -1; + } else { + pmd = pmdp_get_and_clear(mm, old_addr, old_pmd); + VM_BUG_ON(!pmd_none(*new_pmd)); + set_pmd_at(mm, new_addr, new_pmd, pmd); + spin_unlock(&mm->page_table_lock); + ret = 1; + } + } else { + spin_unlock(&mm->page_table_lock); + } +out: + return ret; +} + int change_huge_pmd(struct vm_area_struct *vma, pmd_t *pmd, unsigned long addr, pgprot_t newprot) { diff --git a/mm/mremap.c b/mm/mremap.c index a184f3732e1e..d6959cb4df58 100644 --- a/mm/mremap.c +++ b/mm/mremap.c @@ -41,8 +41,7 @@ static pmd_t *get_old_pmd(struct mm_struct *mm, unsigned long addr) return NULL; pmd = pmd_offset(pud, addr); - split_huge_page_pmd(mm, pmd); - if (pmd_none_or_clear_bad(pmd)) + if (pmd_none(*pmd)) return NULL; return pmd; @@ -65,8 +64,6 @@ static pmd_t *alloc_new_pmd(struct mm_struct *mm, struct vm_area_struct *vma, return NULL; VM_BUG_ON(pmd_trans_huge(*pmd)); - if (pmd_none(*pmd) && __pte_alloc(mm, vma, pmd, addr)) - return NULL; return pmd; } @@ -149,6 +146,23 @@ unsigned long move_page_tables(struct vm_area_struct *vma, new_pmd = alloc_new_pmd(vma->vm_mm, vma, new_addr); if (!new_pmd) break; + if (pmd_trans_huge(*old_pmd)) { + int err = 0; + if (extent == HPAGE_PMD_SIZE) + err = move_huge_pmd(vma, new_vma, old_addr, + new_addr, old_end, + old_pmd, new_pmd); + if (err > 0) { + need_flush = true; + continue; + } else if (!err) { + split_huge_page_pmd(vma->vm_mm, old_pmd); + } + VM_BUG_ON(pmd_trans_huge(*old_pmd)); + } + if (pmd_none(*new_pmd) && __pte_alloc(new_vma->vm_mm, new_vma, + new_pmd, new_addr)) + break; next = (new_addr + PMD_SIZE) & PMD_MASK; if (extent > next - new_addr) extent = next - new_addr; -- cgit v1.2.3 From 3ee9a4f086716d792219c021e8509f91165a4128 Mon Sep 17 00:00:00 2001 From: Joe Perches Date: Mon, 31 Oct 2011 17:08:35 -0700 Subject: mm: neaten warn_alloc_failed Add __attribute__((format (printf...) to the function to validate format and arguments. Use vsprintf extension %pV to avoid any possible message interleaving. Coalesce format string. Convert printks/pr_warning to pr_warn. [akpm@linux-foundation.org: use the __printf() macro] Signed-off-by: Joe Perches Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- include/linux/mm.h | 3 ++- mm/page_alloc.c | 16 +++++++++++----- mm/vmalloc.c | 4 ++-- 3 files changed, 15 insertions(+), 8 deletions(-) (limited to 'mm') diff --git a/include/linux/mm.h b/include/linux/mm.h index 7438071b44aa..3b3e3b8bb706 100644 --- a/include/linux/mm.h +++ b/include/linux/mm.h @@ -1334,7 +1334,8 @@ extern void si_meminfo(struct sysinfo * val); extern void si_meminfo_node(struct sysinfo *val, int nid); extern int after_bootmem; -extern void warn_alloc_failed(gfp_t gfp_mask, int order, const char *fmt, ...); +extern __printf(3, 4) +void warn_alloc_failed(gfp_t gfp_mask, int order, const char *fmt, ...); extern void setup_per_cpu_pageset(void); diff --git a/mm/page_alloc.c b/mm/page_alloc.c index 83a02052bce4..9dd443d89d8b 100644 --- a/mm/page_alloc.c +++ b/mm/page_alloc.c @@ -1754,7 +1754,6 @@ static DEFINE_RATELIMIT_STATE(nopage_rs, void warn_alloc_failed(gfp_t gfp_mask, int order, const char *fmt, ...) { - va_list args; unsigned int filter = SHOW_MEM_FILTER_NODES; if ((gfp_mask & __GFP_NOWARN) || !__ratelimit(&nopage_rs)) @@ -1773,14 +1772,21 @@ void warn_alloc_failed(gfp_t gfp_mask, int order, const char *fmt, ...) filter &= ~SHOW_MEM_FILTER_NODES; if (fmt) { - printk(KERN_WARNING); + struct va_format vaf; + va_list args; + va_start(args, fmt); - vprintk(fmt, args); + + vaf.fmt = fmt; + vaf.va = &args; + + pr_warn("%pV", &vaf); + va_end(args); } - pr_warning("%s: page allocation failure: order:%d, mode:0x%x\n", - current->comm, order, gfp_mask); + pr_warn("%s: page allocation failure: order:%d, mode:0x%x\n", + current->comm, order, gfp_mask); dump_stack(); if (!should_suppress_show_mem()) diff --git a/mm/vmalloc.c b/mm/vmalloc.c index 56faf3163ee2..08ab0aa1406c 100644 --- a/mm/vmalloc.c +++ b/mm/vmalloc.c @@ -1593,8 +1593,8 @@ static void *__vmalloc_area_node(struct vm_struct *area, gfp_t gfp_mask, return area->addr; fail: - warn_alloc_failed(gfp_mask, order, "vmalloc: allocation failure, " - "allocated %ld of %ld bytes\n", + warn_alloc_failed(gfp_mask, order, + "vmalloc: allocation failure, allocated %ld of %ld bytes\n", (area->nr_pages*PAGE_SIZE), area->size); vfree(area->addr); return NULL; -- cgit v1.2.3 From 64212ec569bfdd094f7a23d9b09862209a983559 Mon Sep 17 00:00:00 2001 From: Akinobu Mita Date: Mon, 31 Oct 2011 17:08:38 -0700 Subject: debug-pagealloc: add support for highmem pages This adds support for highmem pages poisoning and verification to the debug-pagealloc feature for no-architecture support. [akpm@linux-foundation.org: remove unneeded preempt_disable/enable] Signed-off-by: Akinobu Mita Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- mm/debug-pagealloc.c | 44 ++++++++++---------------------------------- 1 file changed, 10 insertions(+), 34 deletions(-) (limited to 'mm') diff --git a/mm/debug-pagealloc.c b/mm/debug-pagealloc.c index 2618933efdb3..7cea557407f4 100644 --- a/mm/debug-pagealloc.c +++ b/mm/debug-pagealloc.c @@ -1,6 +1,7 @@ #include #include #include +#include #include #include #include @@ -20,28 +21,13 @@ static inline bool page_poison(struct page *page) return test_bit(PAGE_DEBUG_FLAG_POISON, &page->debug_flags); } -static void poison_highpage(struct page *page) -{ - /* - * Page poisoning for highmem pages is not implemented. - * - * This can be called from interrupt contexts. - * So we need to create a new kmap_atomic slot for this - * application and it will need interrupt protection. - */ -} - static void poison_page(struct page *page) { - void *addr; + void *addr = kmap_atomic(page); - if (PageHighMem(page)) { - poison_highpage(page); - return; - } set_page_poison(page); - addr = page_address(page); memset(addr, PAGE_POISON, PAGE_SIZE); + kunmap_atomic(addr); } static void poison_pages(struct page *page, int n) @@ -86,27 +72,17 @@ static void check_poison_mem(unsigned char *mem, size_t bytes) dump_stack(); } -static void unpoison_highpage(struct page *page) -{ - /* - * See comment in poison_highpage(). - * Highmem pages should not be poisoned for now - */ - BUG_ON(page_poison(page)); -} - static void unpoison_page(struct page *page) { - if (PageHighMem(page)) { - unpoison_highpage(page); + void *addr; + + if (!page_poison(page)) return; - } - if (page_poison(page)) { - void *addr = page_address(page); - check_poison_mem(addr, PAGE_SIZE); - clear_page_poison(page); - } + addr = kmap_atomic(page); + check_poison_mem(addr, PAGE_SIZE); + clear_page_poison(page); + kunmap_atomic(addr); } static void unpoison_pages(struct page *page, int n) -- cgit v1.2.3 From d2ebd0f6b89567eb93ead4e2ca0cbe03021f344b Mon Sep 17 00:00:00 2001 From: "Alex,Shi" Date: Mon, 31 Oct 2011 17:08:39 -0700 Subject: kswapd: avoid unnecessary rebalance after an unsuccessful balancing MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit In commit 215ddd66 ("mm: vmscan: only read new_classzone_idx from pgdat when reclaiming successfully") , Mel Gorman said kswapd is better to sleep after a unsuccessful balancing if there is tighter reclaim request pending in the balancing. But in the following scenario, kswapd do something that is not matched our expectation. The patch fixes this issue. 1, Read pgdat request A (classzone_idx, order = 3) 2, balance_pgdat() 3, During pgdat, a new pgdat request B (classzone_idx, order = 5) is placed 4, balance_pgdat() returns but failed since returned order = 0 5, pgdat of request A assigned to balance_pgdat(), and do balancing again. While the expectation behavior of kswapd should try to sleep. Signed-off-by: Alex Shi Reviewed-by: Tim Chen Acked-by: Mel Gorman Tested-by: Pádraig Brady Cc: Rik van Riel Cc: KOSAKI Motohiro Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- mm/vmscan.c | 14 +++++++++++--- 1 file changed, 11 insertions(+), 3 deletions(-) (limited to 'mm') diff --git a/mm/vmscan.c b/mm/vmscan.c index 77ee24fc891a..dd5fc86dbb82 100644 --- a/mm/vmscan.c +++ b/mm/vmscan.c @@ -2823,7 +2823,9 @@ static void kswapd_try_to_sleep(pg_data_t *pgdat, int order, int classzone_idx) static int kswapd(void *p) { unsigned long order, new_order; + unsigned balanced_order; int classzone_idx, new_classzone_idx; + int balanced_classzone_idx; pg_data_t *pgdat = (pg_data_t*)p; struct task_struct *tsk = current; @@ -2854,7 +2856,9 @@ static int kswapd(void *p) set_freezable(); order = new_order = 0; + balanced_order = 0; classzone_idx = new_classzone_idx = pgdat->nr_zones - 1; + balanced_classzone_idx = classzone_idx; for ( ; ; ) { int ret; @@ -2863,7 +2867,8 @@ static int kswapd(void *p) * new request of a similar or harder type will succeed soon * so consider going to sleep on the basis we reclaimed at */ - if (classzone_idx >= new_classzone_idx && order == new_order) { + if (balanced_classzone_idx >= new_classzone_idx && + balanced_order == new_order) { new_order = pgdat->kswapd_max_order; new_classzone_idx = pgdat->classzone_idx; pgdat->kswapd_max_order = 0; @@ -2878,7 +2883,8 @@ static int kswapd(void *p) order = new_order; classzone_idx = new_classzone_idx; } else { - kswapd_try_to_sleep(pgdat, order, classzone_idx); + kswapd_try_to_sleep(pgdat, balanced_order, + balanced_classzone_idx); order = pgdat->kswapd_max_order; classzone_idx = pgdat->classzone_idx; pgdat->kswapd_max_order = 0; @@ -2895,7 +2901,9 @@ static int kswapd(void *p) */ if (!ret) { trace_mm_vmscan_kswapd_wake(pgdat->node_id, order); - order = balance_pgdat(pgdat, order, &classzone_idx); + balanced_classzone_idx = classzone_idx; + balanced_order = balance_pgdat(pgdat, order, + &balanced_classzone_idx); } } return 0; -- cgit v1.2.3 From d1f0ece6cdca973c01a46dff0eb062baafe78a85 Mon Sep 17 00:00:00 2001 From: Jonghwan Choi Date: Mon, 31 Oct 2011 17:08:42 -0700 Subject: mm/memblock.c: small function definition fixes warning: function 'memblock_memory_can_coalesce' with external linkage has definition. Signed-off-by: Jonghwan Choi Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- mm/memblock.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'mm') diff --git a/mm/memblock.c b/mm/memblock.c index b7ed63633581..7d4f5c8a96cb 100644 --- a/mm/memblock.c +++ b/mm/memblock.c @@ -267,7 +267,7 @@ static int __init_memblock memblock_double_array(struct memblock_type *type) return 0; } -extern int __init_memblock __weak memblock_memory_can_coalesce(phys_addr_t addr1, phys_addr_t size1, +int __init_memblock __weak memblock_memory_can_coalesce(phys_addr_t addr1, phys_addr_t size1, phys_addr_t addr2, phys_addr_t size2) { return 1; -- cgit v1.2.3 From f0dfcde099453aa4c0dc42473828d15a6d492936 Mon Sep 17 00:00:00 2001 From: "Alex,Shi" Date: Mon, 31 Oct 2011 17:08:45 -0700 Subject: kswapd: assign new_order and new_classzone_idx after wakeup in sleeping MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit There 2 places to read pgdat in kswapd. One is return from a successful balance, another is waked up from kswapd sleeping. The new_order and new_classzone_idx represent the balance input order and classzone_idx. But current new_order and new_classzone_idx are not assigned after kswapd_try_to_sleep(), that will cause a bug in the following scenario. 1: after a successful balance, kswapd goes to sleep, and new_order = 0; new_classzone_idx = __MAX_NR_ZONES - 1; 2: kswapd waked up with order = 3 and classzone_idx = ZONE_NORMAL 3: in the balance_pgdat() running, a new balance wakeup happened with order = 5, and classzone_idx = ZONE_NORMAL 4: the first wakeup(order = 3) finished successufly, return order = 3 but, the new_order is still 0, so, this balancing will be treated as a failed balance. And then the second tighter balancing will be missed. So, to avoid the above problem, the new_order and new_classzone_idx need to be assigned for later successful comparison. Signed-off-by: Alex Shi Acked-by: Mel Gorman Reviewed-by: Minchan Kim Tested-by: Pádraig Brady Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- mm/vmscan.c | 2 ++ 1 file changed, 2 insertions(+) (limited to 'mm') diff --git a/mm/vmscan.c b/mm/vmscan.c index dd5fc86dbb82..51bc4bf3f723 100644 --- a/mm/vmscan.c +++ b/mm/vmscan.c @@ -2887,6 +2887,8 @@ static int kswapd(void *p) balanced_classzone_idx); order = pgdat->kswapd_max_order; classzone_idx = pgdat->classzone_idx; + new_order = order; + new_classzone_idx = classzone_idx; pgdat->kswapd_max_order = 0; pgdat->classzone_idx = pgdat->nr_zones - 1; } -- cgit v1.2.3 From de7d2b567d040e3b67fe7121945982f14343213d Mon Sep 17 00:00:00 2001 From: Joe Perches Date: Mon, 31 Oct 2011 17:08:48 -0700 Subject: mm/vmalloc.c: report more vmalloc failures Some vmalloc failure paths do not report OOM conditions. Add warn_alloc_failed, which also does a dump_stack, to those failure paths. This allows more site specific vmalloc failure logging message printks to be removed. Signed-off-by: Joe Perches Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- mm/vmalloc.c | 11 ++++++++--- 1 file changed, 8 insertions(+), 3 deletions(-) (limited to 'mm') diff --git a/mm/vmalloc.c b/mm/vmalloc.c index 08ab0aa1406c..b669aa6f6caf 100644 --- a/mm/vmalloc.c +++ b/mm/vmalloc.c @@ -1625,13 +1625,12 @@ void *__vmalloc_node_range(unsigned long size, unsigned long align, size = PAGE_ALIGN(size); if (!size || (size >> PAGE_SHIFT) > totalram_pages) - return NULL; + goto fail; area = __get_vm_area_node(size, align, VM_ALLOC | VM_UNLIST, start, end, node, gfp_mask, caller); - if (!area) - return NULL; + goto fail; addr = __vmalloc_area_node(area, gfp_mask, prot, node, caller); @@ -1649,6 +1648,12 @@ void *__vmalloc_node_range(unsigned long size, unsigned long align, kmemleak_alloc(addr, real_size, 3, gfp_mask); return addr; + +fail: + warn_alloc_failed(gfp_mask, 0, + "vmalloc: allocation failure: %lu bytes\n", + real_size); + return NULL; } /** -- cgit v1.2.3 From 99ef0315f1b320f392acc4364598340e78758fd2 Mon Sep 17 00:00:00 2001 From: Wanlong Gao Date: Mon, 31 Oct 2011 17:08:51 -0700 Subject: ksm: fix the comment of try_to_unmap_one() try_to_unmap_one() is called by try_to_unmap_ksm(), too. Signed-off-by: Wanlong Gao Cc: Hugh Dickins Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- mm/rmap.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'mm') diff --git a/mm/rmap.c b/mm/rmap.c index 8005080fb9e3..6541cf7fd1d3 100644 --- a/mm/rmap.c +++ b/mm/rmap.c @@ -1164,7 +1164,7 @@ void page_remove_rmap(struct page *page) /* * Subfunctions of try_to_unmap: try_to_unmap_one called - * repeatedly from either try_to_unmap_anon or try_to_unmap_file. + * repeatedly from try_to_unmap_ksm, try_to_unmap_anon or try_to_unmap_file. */ int try_to_unmap_one(struct page *page, struct vm_area_struct *vma, unsigned long address, enum ttu_flags flags) -- cgit v1.2.3 From 20c8c62891a346e09c8d26de41ce78bd7a76c5b0 Mon Sep 17 00:00:00 2001 From: Andrew Morton Date: Mon, 31 Oct 2011 17:08:54 -0700 Subject: mm-add-comment-explaining-task-state-setting-in-bdi_forker_thread-fix fiddle wording Cc: Jan Kara Cc: Wu Fengguang Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- mm/backing-dev.c | 5 ++--- 1 file changed, 2 insertions(+), 3 deletions(-) (limited to 'mm') diff --git a/mm/backing-dev.c b/mm/backing-dev.c index a87da524a4a0..7520ef0bfd47 100644 --- a/mm/backing-dev.c +++ b/mm/backing-dev.c @@ -404,9 +404,8 @@ static int bdi_forker_thread(void *ptr) /* * In the following loop we are going to check whether we have * some work to do without any synchronization with tasks - * waking us up to do work for them. So we have to set task - * state already here so that we don't miss wakeups coming - * after we verify some condition. + * waking us up to do work for them. Set the task state here + * so that we don't miss wakeups after verifying conditions. */ set_current_state(TASK_INTERRUPTIBLE); -- cgit v1.2.3 From 584cff54e1ff8f59d5109dc8093efedff8bcc375 Mon Sep 17 00:00:00 2001 From: Kautuk Consul Date: Mon, 31 Oct 2011 17:08:59 -0700 Subject: mm/mmap.c: eliminate the ret variable from mm_take_all_locks() The ret variable is really not needed in mm_take_all_locks(). Signed-off-by: Kautuk Consul Reviewed-by: Michal Hocko Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- mm/mmap.c | 9 +++------ 1 file changed, 3 insertions(+), 6 deletions(-) (limited to 'mm') diff --git a/mm/mmap.c b/mm/mmap.c index a65efd4db3e1..3c0061f744f5 100644 --- a/mm/mmap.c +++ b/mm/mmap.c @@ -2558,7 +2558,6 @@ int mm_take_all_locks(struct mm_struct *mm) { struct vm_area_struct *vma; struct anon_vma_chain *avc; - int ret = -EINTR; BUG_ON(down_read_trylock(&mm->mmap_sem)); @@ -2579,13 +2578,11 @@ int mm_take_all_locks(struct mm_struct *mm) vm_lock_anon_vma(mm, avc->anon_vma); } - ret = 0; + return 0; out_unlock: - if (ret) - mm_drop_all_locks(mm); - - return ret; + mm_drop_all_locks(mm); + return -EINTR; } static void vm_unlock_anon_vma(struct anon_vma *anon_vma) -- cgit v1.2.3 From dd73e85f6d8f721d66bcbd2734a5f4bc3d3cd768 Mon Sep 17 00:00:00 2001 From: Dean Nelson Date: Mon, 31 Oct 2011 17:09:04 -0700 Subject: HWPOISON: convert pr_debug()s to pr_info()s Commit fb46e73520940b ("HWPOISON: Convert pr_debugs to pr_info) authored by Andi Kleen converted a number of pr_debug()s to pr_info()s. About the same time additional code with pr_debug()s was added by two other commits 8c6c2ecb4466 ("HWPOSION, hugetlb: recover from free hugepage error when !MF_COUNT_INCREASED") and d950b95882f3d ("HWPOISON, hugetlb: soft offlining for hugepage"). And these pr_debug()s failed to get converted to pr_info()s. This patch converts them as well. And does some minor related whitespace cleanup. Signed-off-by: Dean Nelson Reviewed-by: Andi Kleen Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- mm/memory-failure.c | 12 ++++++------ 1 file changed, 6 insertions(+), 6 deletions(-) (limited to 'mm') diff --git a/mm/memory-failure.c b/mm/memory-failure.c index 2b43ba051ac9..edc388db730a 100644 --- a/mm/memory-failure.c +++ b/mm/memory-failure.c @@ -1310,7 +1310,7 @@ int unpoison_memory(unsigned long pfn) * to the end. */ if (PageHuge(page)) { - pr_debug("MCE: Memory failure is now running on free hugepage %#lx\n", pfn); + pr_info("MCE: Memory failure is now running on free hugepage %#lx\n", pfn); return 0; } if (TestClearPageHWPoison(p)) @@ -1419,7 +1419,7 @@ static int soft_offline_huge_page(struct page *page, int flags) if (PageHWPoison(hpage)) { put_page(hpage); - pr_debug("soft offline: %#lx hugepage already poisoned\n", pfn); + pr_info("soft offline: %#lx hugepage already poisoned\n", pfn); return -EBUSY; } @@ -1433,8 +1433,8 @@ static int soft_offline_huge_page(struct page *page, int flags) list_for_each_entry_safe(page1, page2, &pagelist, lru) put_page(page1); - pr_debug("soft offline: %#lx: migration failed %d, type %lx\n", - pfn, ret, page->flags); + pr_info("soft offline: %#lx: migration failed %d, type %lx\n", + pfn, ret, page->flags); if (ret > 0) ret = -EIO; return ret; @@ -1505,7 +1505,7 @@ int soft_offline_page(struct page *page, int flags) } if (!PageLRU(page)) { pr_info("soft_offline: %#lx: unknown non LRU page type %lx\n", - pfn, page->flags); + pfn, page->flags); return -EIO; } @@ -1566,7 +1566,7 @@ int soft_offline_page(struct page *page, int flags) } } else { pr_info("soft offline: %#lx: isolation failed: %d, page count %d, type %lx\n", - pfn, ret, page_count(page), page->flags); + pfn, ret, page_count(page), page->flags); } if (ret) return ret; -- cgit v1.2.3 From d43a87e68e9e71d2987a29cc239acec4e8f410c9 Mon Sep 17 00:00:00 2001 From: Kyungmin Park Date: Mon, 31 Oct 2011 17:09:08 -0700 Subject: mm: compaction: make compact_zone_order() static There's no compact_zone_order() user outside file scope, so make it static. Signed-off-by: Kyungmin Park Acked-by: David Rientjes Reviewed-by: Minchan Kim Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- include/linux/compaction.h | 8 -------- mm/compaction.c | 2 +- 2 files changed, 1 insertion(+), 9 deletions(-) (limited to 'mm') diff --git a/include/linux/compaction.h b/include/linux/compaction.h index cc9f7a428649..bb2bbdbe5464 100644 --- a/include/linux/compaction.h +++ b/include/linux/compaction.h @@ -24,8 +24,6 @@ extern unsigned long try_to_compact_pages(struct zonelist *zonelist, int order, gfp_t gfp_mask, nodemask_t *mask, bool sync); extern unsigned long compaction_suitable(struct zone *zone, int order); -extern unsigned long compact_zone_order(struct zone *zone, int order, - gfp_t gfp_mask, bool sync); /* Do not skip compaction more than 64 times */ #define COMPACT_MAX_DEFER_SHIFT 6 @@ -69,12 +67,6 @@ static inline unsigned long compaction_suitable(struct zone *zone, int order) return COMPACT_SKIPPED; } -static inline unsigned long compact_zone_order(struct zone *zone, int order, - gfp_t gfp_mask, bool sync) -{ - return COMPACT_CONTINUE; -} - static inline void defer_compaction(struct zone *zone) { } diff --git a/mm/compaction.c b/mm/compaction.c index a0e420207ebf..899d95638586 100644 --- a/mm/compaction.c +++ b/mm/compaction.c @@ -582,7 +582,7 @@ out: return ret; } -unsigned long compact_zone_order(struct zone *zone, +static unsigned long compact_zone_order(struct zone *zone, int order, gfp_t gfp_mask, bool sync) { -- cgit v1.2.3 From 4e9dc5df46001510ebd3b3e54faa650f474e51a3 Mon Sep 17 00:00:00 2001 From: Li Haifeng Date: Mon, 31 Oct 2011 17:09:09 -0700 Subject: mm: fix kunmap_high() comment Signed-off-by: Li Haifeng Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- mm/highmem.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'mm') diff --git a/mm/highmem.c b/mm/highmem.c index 5ef672c07f75..e159a7b1cc22 100644 --- a/mm/highmem.c +++ b/mm/highmem.c @@ -250,7 +250,7 @@ void *kmap_high_get(struct page *page) #endif /** - * kunmap_high - map a highmem page into memory + * kunmap_high - unmap a highmem page into memory * @page: &struct page to unmap * * If ARCH_NEEDS_KMAP_HIGH_GET is not defined then this may be called -- cgit v1.2.3 From 3f380998aeb51b99d5d22cadb41162e1e9db70d2 Mon Sep 17 00:00:00 2001 From: Kautuk Consul Date: Mon, 31 Oct 2011 17:09:11 -0700 Subject: vmscan.c: fix invalid strict_strtoul() check in write_scan_unevictable_node() write_scan_unevictable_node() checks the value req returned by strict_strtoul() and returns 1 if req is 0. However, when strict_strtoul() returns 0, it means successful conversion of buf to unsigned long. Due to this, the function was not proceeding to scan the zones for unevictable pages even though we write a valid value to the scan_unevictable_pages sys file. Change this check slightly to check for invalid value in buf as well as 0 value stored in res after successful conversion via strict_strtoul. In both cases, we do not perform the scanning of this node's zones. Signed-off-by: Kautuk Consul Reviewed-by: KAMEZAWA Hiroyuki Cc: Johannes Weiner Cc: Lee Schermerhorn Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- mm/vmscan.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) (limited to 'mm') diff --git a/mm/vmscan.c b/mm/vmscan.c index 51bc4bf3f723..ac644fe85589 100644 --- a/mm/vmscan.c +++ b/mm/vmscan.c @@ -3520,8 +3520,8 @@ static ssize_t write_scan_unevictable_node(struct sys_device *dev, unsigned long res; unsigned long req = strict_strtoul(buf, 10, &res); - if (!req) - return 1; /* zero is no-op */ + if (req || !res) + return 1; /* Invalid input or zero is no-op */ for (zone = node_zones; zone - node_zones < MAX_NR_ZONES; ++zone) { if (!populated_zone(zone)) -- cgit v1.2.3 From 264e56d8247ef6e31ed4386926cae86c61ddcb18 Mon Sep 17 00:00:00 2001 From: Johannes Weiner Date: Mon, 31 Oct 2011 17:09:13 -0700 Subject: mm: disable user interface to manually rescue unevictable pages At one point, anonymous pages were supposed to go on the unevictable list when no swap space was configured, and the idea was to manually rescue those pages after adding swap and making them evictable again. But nowadays, swap-backed pages on the anon LRU list are not scanned without available swap space anyway, so there is no point in moving them to a separate list anymore. The manual rescue could also be used in case pages were stranded on the unevictable list due to race conditions. But the code has been around for a while now and newly discovered bugs should be properly reported and dealt with instead of relying on such a manual fixup. In addition to the lack of a usecase, the sysfs interface to rescue pages from a specific NUMA node has been broken since its introduction, so it's unlikely that anybody ever relied on that. This patch removes the functionality behind the sysctl and the node-interface and emits a one-time warning when somebody tries to access either of them. Signed-off-by: Johannes Weiner Reported-by: Kautuk Consul Reviewed-by: Minchan Kim Acked-by: KAMEZAWA Hiroyuki Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- mm/vmscan.c | 84 ++++++------------------------------------------------------- 1 file changed, 8 insertions(+), 76 deletions(-) (limited to 'mm') diff --git a/mm/vmscan.c b/mm/vmscan.c index ac644fe85589..3886b0bd7869 100644 --- a/mm/vmscan.c +++ b/mm/vmscan.c @@ -3417,66 +3417,12 @@ void scan_mapping_unevictable_pages(struct address_space *mapping) } -/** - * scan_zone_unevictable_pages - check unevictable list for evictable pages - * @zone - zone of which to scan the unevictable list - * - * Scan @zone's unevictable LRU lists to check for pages that have become - * evictable. Move those that have to @zone's inactive list where they - * become candidates for reclaim, unless shrink_inactive_zone() decides - * to reactivate them. Pages that are still unevictable are rotated - * back onto @zone's unevictable list. - */ -#define SCAN_UNEVICTABLE_BATCH_SIZE 16UL /* arbitrary lock hold batch size */ -static void scan_zone_unevictable_pages(struct zone *zone) +static void warn_scan_unevictable_pages(void) { - struct list_head *l_unevictable = &zone->lru[LRU_UNEVICTABLE].list; - unsigned long scan; - unsigned long nr_to_scan = zone_page_state(zone, NR_UNEVICTABLE); - - while (nr_to_scan > 0) { - unsigned long batch_size = min(nr_to_scan, - SCAN_UNEVICTABLE_BATCH_SIZE); - - spin_lock_irq(&zone->lru_lock); - for (scan = 0; scan < batch_size; scan++) { - struct page *page = lru_to_page(l_unevictable); - - if (!trylock_page(page)) - continue; - - prefetchw_prev_lru_page(page, l_unevictable, flags); - - if (likely(PageLRU(page) && PageUnevictable(page))) - check_move_unevictable_page(page, zone); - - unlock_page(page); - } - spin_unlock_irq(&zone->lru_lock); - - nr_to_scan -= batch_size; - } -} - - -/** - * scan_all_zones_unevictable_pages - scan all unevictable lists for evictable pages - * - * A really big hammer: scan all zones' unevictable LRU lists to check for - * pages that have become evictable. Move those back to the zones' - * inactive list where they become candidates for reclaim. - * This occurs when, e.g., we have unswappable pages on the unevictable lists, - * and we add swap to the system. As such, it runs in the context of a task - * that has possibly/probably made some previously unevictable pages - * evictable. - */ -static void scan_all_zones_unevictable_pages(void) -{ - struct zone *zone; - - for_each_zone(zone) { - scan_zone_unevictable_pages(zone); - } + printk_once(KERN_WARNING + "The scan_unevictable_pages sysctl/node-interface has been " + "disabled for lack of a legitimate use case. If you have " + "one, please send an email to linux-mm@kvack.org.\n"); } /* @@ -3489,11 +3435,8 @@ int scan_unevictable_handler(struct ctl_table *table, int write, void __user *buffer, size_t *length, loff_t *ppos) { + warn_scan_unevictable_pages(); proc_doulongvec_minmax(table, write, buffer, length, ppos); - - if (write && *(unsigned long *)table->data) - scan_all_zones_unevictable_pages(); - scan_unevictable_pages = 0; return 0; } @@ -3508,6 +3451,7 @@ static ssize_t read_scan_unevictable_node(struct sys_device *dev, struct sysdev_attribute *attr, char *buf) { + warn_scan_unevictable_pages(); return sprintf(buf, "0\n"); /* always zero; should fit... */ } @@ -3515,19 +3459,7 @@ static ssize_t write_scan_unevictable_node(struct sys_device *dev, struct sysdev_attribute *attr, const char *buf, size_t count) { - struct zone *node_zones = NODE_DATA(dev->id)->node_zones; - struct zone *zone; - unsigned long res; - unsigned long req = strict_strtoul(buf, 10, &res); - - if (req || !res) - return 1; /* Invalid input or zero is no-op */ - - for (zone = node_zones; zone - node_zones < MAX_NR_ZONES; ++zone) { - if (!populated_zone(zone)) - continue; - scan_zone_unevictable_pages(zone); - } + warn_scan_unevictable_pages(); return 1; } -- cgit v1.2.3 From 2d7d3eb2bad116e0d1b3b3930a923c55f6d0f70e Mon Sep 17 00:00:00 2001 From: H Hartley Sweeten Date: Mon, 31 Oct 2011 17:09:15 -0700 Subject: mm/memblock.c: quiet sparse noise Quiet the following sparse noise in this file: warning: symbol 'memblock_overlaps_region' was not declared. Should it be static? Signed-off-by: H Hartley Sweeten Cc: Yinghai Lu Cc: "H. Peter Anvin" Cc: Benjamin Herrenschmidt Cc: Tomi Valkeinen Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- mm/memblock.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) (limited to 'mm') diff --git a/mm/memblock.c b/mm/memblock.c index 7d4f5c8a96cb..84bec4969ed5 100644 --- a/mm/memblock.c +++ b/mm/memblock.c @@ -58,7 +58,8 @@ static unsigned long __init_memblock memblock_addrs_overlap(phys_addr_t base1, p return ((base1 < (base2 + size2)) && (base2 < (base1 + size1))); } -long __init_memblock memblock_overlaps_region(struct memblock_type *type, phys_addr_t base, phys_addr_t size) +static long __init_memblock memblock_overlaps_region(struct memblock_type *type, + phys_addr_t base, phys_addr_t size) { unsigned long i; -- cgit v1.2.3 From 22d5368a0838c00ed0e3ec20e7ff8c6e46ba99ef Mon Sep 17 00:00:00 2001 From: H Hartley Sweeten Date: Mon, 31 Oct 2011 17:09:19 -0700 Subject: mm/thrash.c: quiet sparse noise Quiet the following sparse noise: warning: symbol 'swap_token_memcg' was not declared. Should it be static? Signed-off-by: H Hartley Sweeten Cc: Rik van Riel Cc: KOSAKI Motohiro Cc: KAMEZAWA Hiroyuki Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- mm/thrash.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'mm') diff --git a/mm/thrash.c b/mm/thrash.c index e53f7d02c17c..57ad495dbd54 100644 --- a/mm/thrash.c +++ b/mm/thrash.c @@ -29,7 +29,7 @@ static DEFINE_SPINLOCK(swap_token_lock); struct mm_struct *swap_token_mm; -struct mem_cgroup *swap_token_memcg; +static struct mem_cgroup *swap_token_memcg; #ifdef CONFIG_CGROUP_MEM_RES_CTLR static struct mem_cgroup *swap_token_memcg_from_mm(struct mm_struct *mm) -- cgit v1.2.3 From e754d79d35f0b8612445a9bd7491c48d7317e3ad Mon Sep 17 00:00:00 2001 From: H Hartley Sweeten Date: Mon, 31 Oct 2011 17:09:23 -0700 Subject: mm/mempolicy.c: quiet sparse noise Quiet the spares noise: warning: symbol 'default_policy' was not declared. Should it be static? Signed-off-by: H Hartley Sweeten Cc: KOSAKI Motohiro Cc: Stephen Wilson Cc: Andrea Arcangeli Cc: Mel Gorman Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- mm/mempolicy.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'mm') diff --git a/mm/mempolicy.c b/mm/mempolicy.c index 9c51f9f58cac..cd237f478304 100644 --- a/mm/mempolicy.c +++ b/mm/mempolicy.c @@ -111,7 +111,7 @@ enum zone_type policy_zone = 0; /* * run-time system-wide default policy => local allocation */ -struct mempolicy default_policy = { +static struct mempolicy default_policy = { .refcnt = ATOMIC_INIT(1), /* never free it */ .mode = MPOL_PREFERRED, .flags = MPOL_F_LOCAL, -- cgit v1.2.3 From 2f1da6421570d064a94e17190a4955c2df99794d Mon Sep 17 00:00:00 2001 From: H Hartley Sweeten Date: Mon, 31 Oct 2011 17:09:25 -0700 Subject: mm/huge_memory.c: quiet sparse noise Quiet the sparse noise: warning: symbol 'khugepaged_scan' was not declared. Should it be static? warning: context imbalance in 'khugepaged_scan_mm_slot' - unexpected unlock Signed-off-by: H Hartley Sweeten Cc: Andrea Arcangeli Cc: Rik van Riel Cc: Johannes Weiner Cc: KAMEZAWA Hiroyuki Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- mm/huge_memory.c | 5 ++++- 1 file changed, 4 insertions(+), 1 deletion(-) (limited to 'mm') diff --git a/mm/huge_memory.c b/mm/huge_memory.c index 6b072bdccf81..44f57631cd7c 100644 --- a/mm/huge_memory.c +++ b/mm/huge_memory.c @@ -89,7 +89,8 @@ struct khugepaged_scan { struct list_head mm_head; struct mm_slot *mm_slot; unsigned long address; -} khugepaged_scan = { +}; +static struct khugepaged_scan khugepaged_scan = { .mm_head = LIST_HEAD_INIT(khugepaged_scan.mm_head), }; @@ -2069,6 +2070,8 @@ static void collect_mm_slot(struct mm_slot *mm_slot) static unsigned int khugepaged_scan_mm_slot(unsigned int pages, struct page **hpage) + __releases(&khugepaged_mm_lock) + __acquires(&khugepaged_mm_lock) { struct mm_slot *mm_slot; struct mm_struct *mm; -- cgit v1.2.3 From 21ee9f398be209ccbb62929d35961ca1ed48eec3 Mon Sep 17 00:00:00 2001 From: Minchan Kim Date: Mon, 31 Oct 2011 17:09:28 -0700 Subject: vmscan: add barrier to prevent evictable page in unevictable list When a race between putback_lru_page() and shmem_lock with lock=0 happens, progrom execution order is as follows, but clear_bit in processor #1 could be reordered right before spin_unlock of processor #1. Then, the page would be stranded on the unevictable list. spin_lock SetPageLRU spin_unlock clear_bit(AS_UNEVICTABLE) spin_lock if PageLRU() if !test_bit(AS_UNEVICTABLE) move evictable list smp_mb if !test_bit(AS_UNEVICTABLE) move evictable list spin_unlock But, pagevec_lookup() in scan_mapping_unevictable_pages() has rcu_read_[un]lock() so it could protect reordering before reaching test_bit(AS_UNEVICTABLE) on processor #1 so this problem never happens. But it's a unexpected side effect and we should solve this problem properly. This patch adds a barrier after mapping_clear_unevictable. I didn't meet this problem but just found during review. Signed-off-by: Minchan Kim Acked-by: KOSAKI Motohiro Cc: Mel Gorman Cc: Rik van Riel Cc: Lee Schermerhorn Acked-by: Johannes Weiner Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- mm/shmem.c | 6 ++++++ mm/vmscan.c | 11 ++++++----- 2 files changed, 12 insertions(+), 5 deletions(-) (limited to 'mm') diff --git a/mm/shmem.c b/mm/shmem.c index 2d3577295298..fa4fa6ce13bc 100644 --- a/mm/shmem.c +++ b/mm/shmem.c @@ -1068,6 +1068,12 @@ int shmem_lock(struct file *file, int lock, struct user_struct *user) user_shm_unlock(inode->i_size, user); info->flags &= ~VM_LOCKED; mapping_clear_unevictable(file->f_mapping); + /* + * Ensure that a racing putback_lru_page() can see + * the pages of this mapping are evictable when we + * skip them due to !PageLRU during the scan. + */ + smp_mb__after_clear_bit(); scan_mapping_unevictable_pages(file->f_mapping); } retval = 0; diff --git a/mm/vmscan.c b/mm/vmscan.c index 3886b0bd7869..f51a33e8ed89 100644 --- a/mm/vmscan.c +++ b/mm/vmscan.c @@ -633,13 +633,14 @@ redo: lru = LRU_UNEVICTABLE; add_page_to_unevictable_list(page); /* - * When racing with an mlock clearing (page is - * unlocked), make sure that if the other thread does - * not observe our setting of PG_lru and fails - * isolation, we see PG_mlocked cleared below and move + * When racing with an mlock or AS_UNEVICTABLE clearing + * (page is unlocked) make sure that if the other thread + * does not observe our setting of PG_lru and fails + * isolation/check_move_unevictable_page, + * we see PG_mlocked/AS_UNEVICTABLE cleared below and move * the page back to the evictable list. * - * The other side is TestClearPageMlocked(). + * The other side is TestClearPageMlocked() or shmem_lock(). */ smp_mb(); } -- cgit v1.2.3 From e0887c19b2daa140f20ca8104bdc5740f39dbb86 Mon Sep 17 00:00:00 2001 From: Rik van Riel Date: Mon, 31 Oct 2011 17:09:31 -0700 Subject: vmscan: limit direct reclaim for higher order allocations When suffering from memory fragmentation due to unfreeable pages, THP page faults will repeatedly try to compact memory. Due to the unfreeable pages, compaction fails. Needless to say, at that point page reclaim also fails to create free contiguous 2MB areas. However, that doesn't stop the current code from trying, over and over again, and freeing a minimum of 4MB (2UL << sc->order pages) at every single invocation. This resulted in my 12GB system having 2-3GB free memory, a corresponding amount of used swap and very sluggish response times. This can be avoided by having the direct reclaim code not reclaim from zones that already have plenty of free memory available for compaction. If compaction still fails due to unmovable memory, doing additional reclaim will only hurt the system, not help. [jweiner@redhat.com: change comment to explain the order check] Signed-off-by: Rik van Riel Acked-by: Johannes Weiner Acked-by: Mel Gorman Cc: Andrea Arcangeli Reviewed-by: Minchan Kim Signed-off-by: Johannes Weiner Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- mm/vmscan.c | 16 ++++++++++++++++ 1 file changed, 16 insertions(+) (limited to 'mm') diff --git a/mm/vmscan.c b/mm/vmscan.c index f51a33e8ed89..7e0f05797388 100644 --- a/mm/vmscan.c +++ b/mm/vmscan.c @@ -2125,6 +2125,22 @@ static void shrink_zones(int priority, struct zonelist *zonelist, continue; if (zone->all_unreclaimable && priority != DEF_PRIORITY) continue; /* Let kswapd poll it */ + if (COMPACTION_BUILD) { + /* + * If we already have plenty of memory + * free for compaction, don't free any + * more. Even though compaction is + * invoked for any non-zero order, + * only frequent costly order + * reclamation is disruptive enough to + * become a noticable problem, like + * transparent huge page allocations. + */ + if (sc->order > PAGE_ALLOC_COSTLY_ORDER && + (compaction_suitable(zone, sc->order) || + compaction_deferred(zone))) + continue; + } /* * This steals pages from memory cgroups over softlimit * and returns the number of reclaimed pages and -- cgit v1.2.3 From e0c23279c9f800c403f37511484d9014ac83adec Mon Sep 17 00:00:00 2001 From: Mel Gorman Date: Mon, 31 Oct 2011 17:09:33 -0700 Subject: vmscan: abort reclaim/compaction if compaction can proceed If compaction can proceed, shrink_zones() stops doing any work but its callers still call shrink_slab() which raises the priority and potentially sleeps. This is unnecessary and wasteful so this patch aborts direct reclaim/compaction entirely if compaction can proceed. Signed-off-by: Mel Gorman Acked-by: Rik van Riel Reviewed-by: Minchan Kim Acked-by: Johannes Weiner Cc: Josh Boyer Cc: Andrea Arcangeli Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- mm/vmscan.c | 32 +++++++++++++++++++++----------- 1 file changed, 21 insertions(+), 11 deletions(-) (limited to 'mm') diff --git a/mm/vmscan.c b/mm/vmscan.c index 7e0f05797388..a90c603a8d02 100644 --- a/mm/vmscan.c +++ b/mm/vmscan.c @@ -2103,14 +2103,19 @@ restart: * * If a zone is deemed to be full of pinned pages then just give it a light * scan then give up on it. + * + * This function returns true if a zone is being reclaimed for a costly + * high-order allocation and compaction is either ready to begin or deferred. + * This indicates to the caller that it should retry the allocation or fail. */ -static void shrink_zones(int priority, struct zonelist *zonelist, +static bool shrink_zones(int priority, struct zonelist *zonelist, struct scan_control *sc) { struct zoneref *z; struct zone *zone; unsigned long nr_soft_reclaimed; unsigned long nr_soft_scanned; + bool should_abort_reclaim = false; for_each_zone_zonelist_nodemask(zone, z, zonelist, gfp_zone(sc->gfp_mask), sc->nodemask) { @@ -2127,19 +2132,20 @@ static void shrink_zones(int priority, struct zonelist *zonelist, continue; /* Let kswapd poll it */ if (COMPACTION_BUILD) { /* - * If we already have plenty of memory - * free for compaction, don't free any - * more. Even though compaction is - * invoked for any non-zero order, - * only frequent costly order - * reclamation is disruptive enough to - * become a noticable problem, like - * transparent huge page allocations. + * If we already have plenty of memory free for + * compaction in this zone, don't free any more. + * Even though compaction is invoked for any + * non-zero order, only frequent costly order + * reclamation is disruptive enough to become a + * noticable problem, like transparent huge page + * allocations. */ if (sc->order > PAGE_ALLOC_COSTLY_ORDER && (compaction_suitable(zone, sc->order) || - compaction_deferred(zone))) + compaction_deferred(zone))) { + should_abort_reclaim = true; continue; + } } /* * This steals pages from memory cgroups over softlimit @@ -2158,6 +2164,8 @@ static void shrink_zones(int priority, struct zonelist *zonelist, shrink_zone(priority, zone, sc); } + + return should_abort_reclaim; } static bool zone_reclaimable(struct zone *zone) @@ -2222,7 +2230,9 @@ static unsigned long do_try_to_free_pages(struct zonelist *zonelist, sc->nr_scanned = 0; if (!priority) disable_swap_token(sc->mem_cgroup); - shrink_zones(priority, zonelist, sc); + if (shrink_zones(priority, zonelist, sc)) + break; + /* * Don't shrink slabs when reclaiming memory from * over limit cgroups -- cgit v1.2.3 From df9d6985be2a7e7683c46e4c6ea608fc69f02b45 Mon Sep 17 00:00:00 2001 From: Christoph Lameter Date: Mon, 31 Oct 2011 17:09:35 -0700 Subject: mm: do not drain pagevecs for mlockall(MCL_FUTURE) MCL_FUTURE does not move pages between lru list and draining the LRU per cpu pagevecs is a nasty activity. Avoid doing it unecessarily. Signed-off-by: Christoph Lameter Cc: David Rientjes Reviewed-by: Minchan Kim Acked-by: KOSAKI Motohiro Cc: Mel Gorman Acked-by: Johannes Weiner Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- mm/mlock.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) (limited to 'mm') diff --git a/mm/mlock.c b/mm/mlock.c index 048260c4e02e..7debb4fdf79b 100644 --- a/mm/mlock.c +++ b/mm/mlock.c @@ -549,7 +549,8 @@ SYSCALL_DEFINE1(mlockall, int, flags) if (!can_do_mlock()) goto out; - lru_add_drain_all(); /* flush pagevec */ + if (flags & MCL_CURRENT) + lru_add_drain_all(); /* flush pagevec */ down_write(¤t->mm->mmap_sem); -- cgit v1.2.3 From 0089e4853ae1ac161fae5137170971ccb6f4f152 Mon Sep 17 00:00:00 2001 From: Hillf Danton Date: Mon, 31 Oct 2011 17:09:38 -0700 Subject: mm/huge_memory: fix copying user highpage The THP copy-on-write handler falls back to regular-sized pages for a huge page replacement upon allocation failure or if THP has been individually disabled in the target VMA. The loop responsible for copying page-sized chunks accidentally uses multiples of PAGE_SHIFT instead of PAGE_SIZE as the virtual address arg for copy_user_highpage(). Signed-off-by: Hillf Danton Acked-by: Johannes Weiner Reviewed-by: Andrea Arcangeli Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- mm/huge_memory.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'mm') diff --git a/mm/huge_memory.c b/mm/huge_memory.c index 44f57631cd7c..ef954384f53a 100644 --- a/mm/huge_memory.c +++ b/mm/huge_memory.c @@ -830,7 +830,7 @@ static int do_huge_pmd_wp_page_fallback(struct mm_struct *mm, for (i = 0; i < HPAGE_PMD_NR; i++) { copy_user_highpage(pages[i], page + i, - haddr + PAGE_SHIFT*i, vma); + haddr + PAGE_SIZE * i, vma); __SetPageUptodate(pages[i]); cond_resched(); } -- cgit v1.2.3 From 35d8c7ad7208dad5d352c483408e555022750978 Mon Sep 17 00:00:00 2001 From: Hillf Danton Date: Mon, 31 Oct 2011 17:09:40 -0700 Subject: mm/huge_memory: fix typo when updating mmu cache There are three cases of update_mmu_cache() in the file, and the case in function collapse_huge_page() has a typo, namely the last parameter used, which is corrected based on the other two cases. Due to the define of update_mmu_cache by X86, the only arch that implements THP currently, the change here has no really crystal point, but one or two minutes of efforts could be saved for those archs that are likely to support THP in future. Signed-off-by: Hillf Danton Cc: Johannes Weiner Reviewed-by: Andrea Arcangeli Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- mm/huge_memory.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'mm') diff --git a/mm/huge_memory.c b/mm/huge_memory.c index ef954384f53a..860ec211ddd6 100644 --- a/mm/huge_memory.c +++ b/mm/huge_memory.c @@ -1952,7 +1952,7 @@ static void collapse_huge_page(struct mm_struct *mm, BUG_ON(!pmd_none(*pmd)); page_add_new_anon_rmap(new_page, vma, address); set_pmd_at(mm, address, pmd, _pmd); - update_mmu_cache(vma, address, entry); + update_mmu_cache(vma, address, _pmd); prepare_pmd_huge_pte(pgtable, mm); mm->nr_ptes--; spin_unlock(&mm->page_table_lock); -- cgit v1.2.3 From 3d470fc385defa60d9af610f05db8e7f8b4f2f5e Mon Sep 17 00:00:00 2001 From: Hugh Dickins Date: Mon, 31 Oct 2011 17:09:43 -0700 Subject: mm: munlock use mapcount to avoid terrible overhead A process spent 30 minutes exiting, just munlocking the pages of a large anonymous area that had been alternately mprotected into page-sized vmas: for every single page there's an anon_vma walk through all the other little vmas to find the right one. A general fix to that would be a lot more complicated (use prio_tree on anon_vma?), but there's one very simple thing we can do to speed up the common case: if a page to be munlocked is mapped only once, then it is our vma that it is mapped into, and there's no need whatever to walk through all the others. Okay, there is a very remote race in munlock_vma_pages_range(), if between its follow_page() and lock_page(), another process were to munlock the same page, then page reclaim remove it from our vma, then another process mlock it again. We would find it with page_mapcount 1, yet it's still mlocked in another process. But never mind, that's much less likely than the down_read_trylock() failure which munlocking already tolerates (in try_to_unmap_one()): in due course page reclaim will discover and move the page to unevictable instead. [akpm@linux-foundation.org: add comment] Signed-off-by: Hugh Dickins Cc: Michel Lespinasse Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- mm/mlock.c | 10 +++++++++- 1 file changed, 9 insertions(+), 1 deletion(-) (limited to 'mm') diff --git a/mm/mlock.c b/mm/mlock.c index 7debb4fdf79b..bd34b3a10852 100644 --- a/mm/mlock.c +++ b/mm/mlock.c @@ -110,7 +110,15 @@ void munlock_vma_page(struct page *page) if (TestClearPageMlocked(page)) { dec_zone_page_state(page, NR_MLOCK); if (!isolate_lru_page(page)) { - int ret = try_to_munlock(page); + int ret = SWAP_AGAIN; + + /* + * Optimization: if the page was mapped just once, + * that's our mapping and we don't need to check all the + * other vmas. + */ + if (page_mapcount(page) > 1) + ret = try_to_munlock(page); /* * did try_to_unlock() succeed or punt? */ -- cgit v1.2.3 From a1cb2c60ddc98ff4e5246f410558805401ceee67 Mon Sep 17 00:00:00 2001 From: Dimitri Sivanich Date: Mon, 31 Oct 2011 17:09:46 -0700 Subject: mm/vmstat.c: cache align vm_stat Avoid false sharing of the vm_stat array. This was found to adversely affect tmpfs I/O performance. Tests run on a 640 cpu UV system. With 120 threads doing parallel writes, each to different tmpfs mounts: No patch: ~300 MB/sec With vm_stat alignment: ~430 MB/sec Signed-off-by: Dimitri Sivanich Acked-by: Christoph Lameter Acked-by: Mel Gorman Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- mm/vmstat.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'mm') diff --git a/mm/vmstat.c b/mm/vmstat.c index 56e529a40517..8fd603b1665e 100644 --- a/mm/vmstat.c +++ b/mm/vmstat.c @@ -78,7 +78,7 @@ void vm_events_fold_cpu(int cpu) * * vm_stat contains the global counters */ -atomic_long_t vm_stat[NR_VM_ZONE_STAT_ITEMS]; +atomic_long_t vm_stat[NR_VM_ZONE_STAT_ITEMS] __cacheline_aligned_in_smp; EXPORT_SYMBOL(vm_stat); #ifdef CONFIG_SMP -- cgit v1.2.3