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2011-11-24slub: avoid potential NULL dereference or corruptionEric Dumazet1-10/+11
show_slab_objects() can trigger NULL dereferences or memory corruption. Another cpu can change its c->page to NULL or c->node to NUMA_NO_NODE while we use them. Use ACCESS_ONCE(c->page) and ACCESS_ONCE(c->node) to make sure this cannot happen. Acked-by: Christoph Lameter <cl@linux.com> Acked-by: David Rientjes <rientjes@google.com> Signed-off-by: Eric Dumazet <eric.dumazet@gmail.com> Signed-off-by: Pekka Enberg <penberg@kernel.org>
2011-11-24slub: use irqsafe_cpu_cmpxchg for put_cpu_partialChristoph Lameter1-1/+1
The cmpxchg must be irq safe. The fallback for this_cpu_cmpxchg only disables preemption which results in per cpu partial page operation potentially failing on non x86 platforms. This patch fixes the following problem reported by Christian Kujau: I seem to hit it with heavy disk & cpu IO is in progress on this PowerBook G4. Full dmesg & .config: http://nerdbynature.de/bits/3.2.0-rc1/oops/ I've enabled some debug options and now it really points to slub.c:2166 http://nerdbynature.de/bits/3.2.0-rc1/oops/oops4m.jpg With debug options enabled I'm currently in the xmon debugger, not sure what to make of it yet, I'll try to get something useful out of it :) Reported-by: Christian Kujau <lists@nerdbynature.de> Tested-by: Christian Kujau <lists@nerdbynature.de> Acked-by: Eric Dumazet <eric.dumazet@gmail.com> Acked-by: David Rientjes <rientjes@google.com> Signed-off-by: Christoph Lameter <cl@linux.com> Signed-off-by: Pekka Enberg <penberg@kernel.org>
2011-11-15slub: move discard_slab out of node lockShaohua Li1-4/+12
Lockdep reports there is potential deadlock for slub node list_lock. discard_slab() is called with the lock hold in unfreeze_partials(), which could trigger a slab allocation, which could hold the lock again. discard_slab() doesn't need hold the lock actually, if the slab is already removed from partial list. Acked-by: Christoph Lameter <cl@linux.com> Reported-and-tested-by: Yong Zhang <yong.zhang0@gmail.com> Reported-and-tested-by: Julie Sullivan <kernelmail.jms@gmail.com> Signed-off-by: Shaohua Li <shaohua.li@intel.com> Signed-off-by: Pekka Enberg <penberg@kernel.org>
2011-11-15slub: use correct parameter to add a page to partial list tailShaohua Li1-1/+2
unfreeze_partials() needs add the page to partial list tail, since such page hasn't too many free objects. We now explictly use DEACTIVATE_TO_TAIL for this, while DEACTIVATE_TO_TAIL != 1. This will cause performance regression (eg, more lock contention in node->list_lock) without below fix. Signed-off-by: Shaohua Li <shaohua.li@intel.com> Acked-by: Christoph Lameter <cl@linux.com> Acked-by: David Rientjes <rientjes@google.com> Signed-off-by: Pekka Enberg <penberg@kernel.org>
2011-10-31lib/string.c: introduce memchr_inv()Akinobu Mita1-45/+2
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 <akinobu.mita@gmail.com> Acked-by: Christoph Lameter <cl@linux-foundation.org> Acked-by: Pekka Enberg <penberg@kernel.org> Cc: Matt Mackall <mpm@selenic.com> Acked-by: Joern Engel <joern@logfs.org> Cc: Marcin Slusarz <marcin.slusarz@gmail.com> Cc: Eric Dumazet <eric.dumazet@gmail.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2011-10-26Merge branches 'slab/next' and 'slub/partial' into slab/for-linusPekka Enberg1-166/+392
2011-09-27slub: Discard slab page when node partial > minimum partial numberAlex Shi1-1/+1
Discarding slab should be done when node partial > min_partial. Otherwise, node partial slab may eat up all memory. Signed-off-by: Alex Shi <alex.shi@intel.com> Acked-by: Christoph Lameter <cl@linux.com> Signed-off-by: Pekka Enberg <penberg@kernel.org>
2011-09-27slub: correct comments error for per cpu partialAlex Shi1-1/+1
Correct comment errors, that mistake cpu partial objects number as pages number, may make reader misunderstand. Signed-off-by: Alex Shi <alex.shi@intel.com> Reviewed-by: Christoph Lameter <cl@linux.com> Signed-off-by: Pekka Enberg <penberg@kernel.org>
2011-09-27mm: restrict access to slab files under procfs and sysfsVasiliy Kulikov1-3/+4
Historically /proc/slabinfo and files under /sys/kernel/slab/* have world read permissions and are accessible to the world. slabinfo contains rather private information related both to the kernel and userspace tasks. Depending on the situation, it might reveal either private information per se or information useful to make another targeted attack. Some examples of what can be learned by reading/watching for /proc/slabinfo entries: 1) dentry (and different *inode*) number might reveal other processes fs activity. The number of dentry "active objects" doesn't strictly show file count opened/touched by a process, however, there is a good correlation between them. The patch "proc: force dcache drop on unauthorized access" relies on the privacy of dentry count. 2) different inode entries might reveal the same information as (1), but these are more fine granted counters. If a filesystem is mounted in a private mount point (or even a private namespace) and fs type differs from other mounted fs types, fs activity in this mount point/namespace is revealed. If there is a single ecryptfs mount point, the whole fs activity of a single user is revealed. Number of files in ecryptfs mount point is a private information per se. 3) fuse_* reveals number of files / fs activity of a user in a user private mount point. It is approx. the same severity as ecryptfs infoleak in (2). 4) sysfs_dir_cache similar to (2) reveals devices' addition/removal, which can be otherwise hidden by "chmod 0700 /sys/". With 0444 slabinfo the precise number of sysfs files is known to the world. 5) buffer_head might reveal some kernel activity. With other information leaks an attacker might identify what specific kernel routines generate buffer_head activity. 6) *kmalloc* infoleaks are very situational. Attacker should watch for the specific kmalloc size entry and filter the noise related to the unrelated kernel activity. If an attacker has relatively silent victim system, he might get rather precise counters. Additional information sources might significantly increase the slabinfo infoleak benefits. E.g. if an attacker knows that the processes activity on the system is very low (only core daemons like syslog and cron), he may run setxid binaries / trigger local daemon activity / trigger network services activity / await sporadic cron jobs activity / etc. and get rather precise counters for fs and network activity of these privileged tasks, which is unknown otherwise. Also hiding slabinfo and /sys/kernel/slab/* is a one step to complicate exploitation of kernel heap overflows (and possibly, other bugs). The related discussion: http://thread.gmane.org/gmane.linux.kernel/1108378 To keep compatibility with old permission model where non-root monitoring daemon could watch for kernel memleaks though slabinfo one should do: groupadd slabinfo usermod -a -G slabinfo $MONITOR_USER And add the following commands to init scripts (to mountall.conf in Ubuntu's upstart case): chmod g+r /proc/slabinfo /sys/kernel/slab/*/* chgrp slabinfo /proc/slabinfo /sys/kernel/slab/*/* Signed-off-by: Vasiliy Kulikov <segoon@openwall.com> Reviewed-by: Kees Cook <kees@ubuntu.com> Reviewed-by: Dave Hansen <dave@linux.vnet.ibm.com> Acked-by: Christoph Lameter <cl@gentwo.org> Acked-by: David Rientjes <rientjes@google.com> CC: Valdis.Kletnieks@vt.edu CC: Linus Torvalds <torvalds@linux-foundation.org> CC: Alan Cox <alan@linux.intel.com> Signed-off-by: Pekka Enberg <penberg@kernel.org>
2011-09-19Merge branch 'slab/urgent' into slab/nextPekka Enberg1-10/+12
2011-09-13slub: Code optimization in get_partial_node()Alex,Shi1-4/+2
I find a way to reduce a variable in get_partial_node(). That is also helpful for code understanding. Acked-by: Christoph Lameter <cl@linux.com> Signed-off-by: Alex Shi <alex.shi@intel.com> Signed-off-by: Pekka Enberg <penberg@kernel.org>
2011-08-27slub: explicitly document position of inserting slab to partial listShaohua Li1-6/+6
Adding slab to partial list head/tail is sensitive to performance. So explicitly uses DEACTIVATE_TO_TAIL/DEACTIVATE_TO_HEAD to document it to avoid we get it wrong. Acked-by: Christoph Lameter <cl@linux.com> Signed-off-by: Shaohua Li <shli@kernel.org> Signed-off-by: Shaohua Li <shaohua.li@intel.com> Signed-off-by: Pekka Enberg <penberg@kernel.org>
2011-08-27slub: add slab with one free object to partial list tailShaohua Li1-1/+1
The slab has just one free object, adding it to partial list head doesn't make sense. And it can cause lock contentation. For example, 1. CPU takes the slab from partial list 2. fetch an object 3. switch to another slab 4. free an object, then the slab is added to partial list again In this way n->list_lock will be heavily contended. In fact, Alex had a hackbench regression. 3.1-rc1 performance drops about 70% against 3.0. This patch fixes it. Acked-by: Christoph Lameter <cl@linux.com> Reported-by: Alex Shi <alex.shi@intel.com> Signed-off-by: Shaohua Li <shli@kernel.org> Signed-off-by: Shaohua Li <shaohua.li@intel.com> Signed-off-by: Pekka Enberg <penberg@kernel.org>
2011-08-19slub: per cpu cache for partial pagesChristoph Lameter1-47/+292
Allow filling out the rest of the kmem_cache_cpu cacheline with pointers to partial pages. The partial page list is used in slab_free() to avoid per node lock taking. In __slab_alloc() we can then take multiple partial pages off the per node partial list in one go reducing node lock pressure. We can also use the per cpu partial list in slab_alloc() to avoid scanning partial lists for pages with free objects. The main effect of a per cpu partial list is that the per node list_lock is taken for batches of partial pages instead of individual ones. Potential future enhancements: 1. The pickup from the partial list could be perhaps be done without disabling interrupts with some work. The free path already puts the page into the per cpu partial list without disabling interrupts. 2. __slab_free() may have some code paths that could use optimization. Performance: Before After ./hackbench 100 process 200000 Time: 1953.047 1564.614 ./hackbench 100 process 20000 Time: 207.176 156.940 ./hackbench 100 process 20000 Time: 204.468 156.940 ./hackbench 100 process 20000 Time: 204.879 158.772 ./hackbench 10 process 20000 Time: 20.153 15.853 ./hackbench 10 process 20000 Time: 20.153 15.986 ./hackbench 10 process 20000 Time: 19.363 16.111 ./hackbench 1 process 20000 Time: 2.518 2.307 ./hackbench 1 process 20000 Time: 2.258 2.339 ./hackbench 1 process 20000 Time: 2.864 2.163 Signed-off-by: Christoph Lameter <cl@linux.com> Signed-off-by: Pekka Enberg <penberg@kernel.org>
2011-08-19slub: return object pointer from get_partial() / new_slab().Christoph Lameter1-60/+73
There is no need anymore to return the pointer to a slab page from get_partial() since the page reference can be stored in the kmem_cache_cpu structures "page" field. Return an object pointer instead. That in turn allows a simplification of the spaghetti code in __slab_alloc(). Signed-off-by: Christoph Lameter <cl@linux.com> Signed-off-by: Pekka Enberg <penberg@kernel.org>
2011-08-19slub: pass kmem_cache_cpu pointer to get_partial()Christoph Lameter1-15/+15
Pass the kmem_cache_cpu pointer to get_partial(). That way we can avoid the this_cpu_write() statements. Signed-off-by: Christoph Lameter <cl@linux.com> Signed-off-by: Pekka Enberg <penberg@kernel.org>
2011-08-19slub: Prepare inuse field in new_slab()Christoph Lameter1-3/+2
inuse will always be set to page->objects. There is no point in initializing the field to zero in new_slab() and then overwriting the value in __slab_alloc(). Signed-off-by: Christoph Lameter <cl@linux.com> Signed-off-by: Pekka Enberg <penberg@kernel.org>
2011-08-19slub: Remove useless statements in __slab_allocChristoph Lameter1-4/+0
Two statements in __slab_alloc() do not have any effect. 1. c->page is already set to NULL by deactivate_slab() called right before. 2. gfpflags are masked in new_slab() before being passed to the page allocator. There is no need to mask gfpflags in __slab_alloc in particular since most frequent processing in __slab_alloc does not require the use of a gfpmask. Cc: torvalds@linux-foundation.org Signed-off-by: Christoph Lameter <cl@linux.com> Signed-off-by: Pekka Enberg <penberg@kernel.org>
2011-08-19slub: free slabs without holding locksChristoph Lameter1-13/+13
There are two situations in which slub holds a lock while releasing pages: A. During kmem_cache_shrink() B. During kmem_cache_close() For A build a list while holding the lock and then release the pages later. In case of B we are the last remaining user of the slab so there is no need to take the listlock. After this patch all calls to the page allocator to free pages are done without holding any spinlocks. kmem_cache_destroy() will still hold the slub_lock semaphore. Signed-off-by: Christoph Lameter <cl@linux.com> Signed-off-by: Pekka Enberg <penberg@kernel.org>
2011-08-09slub: Fix partial count comparison confusionChristoph Lameter1-1/+1
deactivate_slab() has the comparison if more than the minimum number of partial pages are in the partial list wrong. An effect of this may be that empty pages are not freed from deactivate_slab(). The result could be an OOM due to growth of the partial slabs per node. Frees mostly occur from __slab_free which is okay so this would only affect use cases where a lot of switching around of per cpu slabs occur. Switching per cpu slabs occurs with high frequency if debugging options are enabled. Reported-and-tested-by: Xiaotian Feng <xtfeng@gmail.com> Signed-off-by: Christoph Lameter <cl@linux.com> Signed-off-by: Pekka Enberg <penberg@kernel.org>
2011-08-09slub: fix check_bytes() for slub debuggingAkinobu Mita1-1/+1
The check_bytes() function is used by slub debugging. It returns a pointer to the first unmatching byte for a character in the given memory area. If the character for matching byte is greater than 0x80, check_bytes() doesn't work. Becuase 64-bit pattern is generated as below. value64 = value | value << 8 | value << 16 | value << 24; value64 = value64 | value64 << 32; The integer promotions are performed and sign-extended as the type of value is u8. The upper 32 bits of value64 is 0xffffffff in the first line, and the second line has no effect. This fixes the 64-bit pattern generation. Signed-off-by: Akinobu Mita <akinobu.mita@gmail.com> Cc: Christoph Lameter <cl@linux-foundation.org> Cc: Matt Mackall <mpm@selenic.com> Reviewed-by: Marcin Slusarz <marcin.slusarz@gmail.com> Acked-by: Eric Dumazet <eric.dumazet@gmail.com> Signed-off-by: Pekka Enberg <penberg@kernel.org>
2011-08-09slub: Fix full list corruption if debugging is onChristoph Lameter1-2/+4
When a slab is freed by __slab_free() and the slab can only contain a single object ever then it was full (and therefore not on the partial lists but on the full list in the debug case) before we reached slab_empty. This caused the following full list corruption when SLUB debugging was enabled: [ 5913.233035] ------------[ cut here ]------------ [ 5913.233097] WARNING: at lib/list_debug.c:53 __list_del_entry+0x8d/0x98() [ 5913.233101] Hardware name: Adamo 13 [ 5913.233105] list_del corruption. prev->next should be ffffea000434fd20, but was ffffea0004199520 [ 5913.233108] Modules linked in: nfs fscache fuse ebtable_nat ebtables ppdev parport_pc lp parport ipt_MASQUERADE iptable_nat nf_nat nfsd lockd nfs_acl auth_rpcgss xt_CHECKSUM sunrpc iptable_mangle bridge stp llc cpufreq_ondemand acpi_cpufreq freq_table mperf ip6t_REJECT nf_conntrack_ipv6 nf_defrag_ipv6 ip6table_filter ip6_tables rfcomm bnep arc4 iwlagn snd_hda_codec_hdmi snd_hda_codec_idt snd_hda_intel btusb mac80211 snd_hda_codec bluetooth snd_hwdep snd_seq snd_seq_device snd_pcm usb_debug dell_wmi sparse_keymap cdc_ether usbnet cdc_acm uvcvideo cdc_wdm mii cfg80211 snd_timer dell_laptop videodev dcdbas snd microcode v4l2_compat_ioctl32 soundcore joydev tg3 pcspkr snd_page_alloc iTCO_wdt i2c_i801 rfkill iTCO_vendor_support wmi virtio_net kvm_intel kvm ipv6 xts gf128mul dm_crypt i915 drm_kms_helper drm i2c_algo_bit i2c_core video [last unloaded: scsi_wait_scan] [ 5913.233213] Pid: 0, comm: swapper Not tainted 3.0.0+ #127 [ 5913.233213] Call Trace: [ 5913.233213] <IRQ> [<ffffffff8105df18>] warn_slowpath_common+0x83/0x9b [ 5913.233213] [<ffffffff8105dfd3>] warn_slowpath_fmt+0x46/0x48 [ 5913.233213] [<ffffffff8127e7c1>] __list_del_entry+0x8d/0x98 [ 5913.233213] [<ffffffff8127e7da>] list_del+0xe/0x2d [ 5913.233213] [<ffffffff814e0430>] __slab_free+0x1db/0x235 [ 5913.233213] [<ffffffff811706ab>] ? bvec_free_bs+0x35/0x37 [ 5913.233213] [<ffffffff811706ab>] ? bvec_free_bs+0x35/0x37 [ 5913.233213] [<ffffffff811706ab>] ? bvec_free_bs+0x35/0x37 [ 5913.233213] [<ffffffff81133085>] kmem_cache_free+0x88/0x102 [ 5913.233213] [<ffffffff811706ab>] bvec_free_bs+0x35/0x37 [ 5913.233213] [<ffffffff811706e1>] bio_free+0x34/0x64 [ 5913.233213] [<ffffffff813dc390>] dm_bio_destructor+0x12/0x14 [ 5913.233213] [<ffffffff8116fef6>] bio_put+0x2b/0x2d [ 5913.233213] [<ffffffff813dccab>] clone_endio+0x9e/0xb4 [ 5913.233213] [<ffffffff8116f7dd>] bio_endio+0x2d/0x2f [ 5913.233213] [<ffffffffa00148da>] crypt_dec_pending+0x5c/0x8b [dm_crypt] [ 5913.233213] [<ffffffffa00150a9>] crypt_endio+0x78/0x81 [dm_crypt] [ Full discussion here: https://lkml.org/lkml/2011/8/4/375 ] Make sure that we remove such a slab also from the full lists. Reported-and-tested-by: Dave Jones <davej@redhat.com> Reported-and-tested-by: Xiaotian Feng <xtfeng@gmail.com> Signed-off-by: Christoph Lameter <cl@linux.com> Signed-off-by: Pekka Enberg <penberg@kernel.org>
2011-07-31slub: use print_hex_dumpSebastian Andrzej Siewior1-35/+9
Less code and same functionality. The output would be: | Object c7428000: 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b kkkkkkkkkkkkkkkk | Object c7428010: 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b kkkkkkkkkkkkkkkk | Object c7428020: 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b kkkkkkkkkkkkkkkk | Object c7428030: 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b a5 kkkkkkkkkkk. | Redzone c742803c: bb bb bb bb .... | Padding c7428064: 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a ZZZZZZZZZZZZZZZZ | Padding c7428074: 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a ZZZZZZZZZZZZ Acked-by: Christoph Lameter <cl@linux.com> Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de> Signed-off-by: Pekka Enberg <penberg@kernel.org>
2011-07-30Merge branch 'slub/lockless' of ↵Linus Torvalds1-252/+512
git://git.kernel.org/pub/scm/linux/kernel/git/penberg/slab-2.6 * 'slub/lockless' of git://git.kernel.org/pub/scm/linux/kernel/git/penberg/slab-2.6: (21 commits) slub: When allocating a new slab also prep the first object slub: disable interrupts in cmpxchg_double_slab when falling back to pagelock Avoid duplicate _count variables in page_struct Revert "SLUB: Fix build breakage in linux/mm_types.h" SLUB: Fix build breakage in linux/mm_types.h slub: slabinfo update for cmpxchg handling slub: Not necessary to check for empty slab on load_freelist slub: fast release on full slab slub: Add statistics for the case that the current slab does not match the node slub: Get rid of the another_slab label slub: Avoid disabling interrupts in free slowpath slub: Disable interrupts in free_debug processing slub: Invert locking and avoid slab lock slub: Rework allocator fastpaths slub: Pass kmem_cache struct to lock and freeze slab slub: explicit list_lock taking slub: Add cmpxchg_double_slab() mm: Rearrange struct page slub: Move page->frozen handling near where the page->freelist handling occurs slub: Do not use frozen page flag but a bit in the page counters ...
2011-07-25Merge branch 'for-linus' of ↵Linus Torvalds1-1/+1
git://git.kernel.org/pub/scm/linux/kernel/git/jikos/trivial * 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/jikos/trivial: (43 commits) fs: Merge split strings treewide: fix potentially dangerous trailing ';' in #defined values/expressions uwb: Fix misspelling of neighbourhood in comment net, netfilter: Remove redundant goto in ebt_ulog_packet trivial: don't touch files that are removed in the staging tree lib/vsprintf: replace link to Draft by final RFC number doc: Kconfig: `to be' -> `be' doc: Kconfig: Typo: square -> squared doc: Konfig: Documentation/power/{pm => apm-acpi}.txt drivers/net: static should be at beginning of declaration drivers/media: static should be at beginning of declaration drivers/i2c: static should be at beginning of declaration XTENSA: static should be at beginning of declaration SH: static should be at beginning of declaration MIPS: static should be at beginning of declaration ARM: static should be at beginning of declaration rcu: treewide: Do not use rcu_read_lock_held when calling rcu_dereference_check Update my e-mail address PCIe ASPM: forcedly -> forcibly gma500: push through device driver tree ... Fix up trivial conflicts: - arch/arm/mach-ep93xx/dma-m2p.c (deleted) - drivers/gpio/gpio-ep93xx.c (renamed and context nearby) - drivers/net/r8169.c (just context changes)
2011-07-25slub: When allocating a new slab also prep the first objectChristoph Lameter1-0/+3
We need to branch to the debug code for the first object if we allocate a new slab otherwise the first object will be marked wrongly as inactive. Tested-by: Rabin Vincent <rabin@rab.in> Signed-off-by: Christoph Lameter <cl@linux.com> Signed-off-by: Pekka Enberg <penberg@kernel.org>
2011-07-22Merge branch 'slab-for-linus' of ↵Linus Torvalds1-2/+103
git://git.kernel.org/pub/scm/linux/kernel/git/penberg/slab-2.6 * 'slab-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/penberg/slab-2.6: slab: fix DEBUG_SLAB warning slab: shrink sizeof(struct kmem_cache) slab: fix DEBUG_SLAB build SLUB: Fix missing <linux/stacktrace.h> include slub: reduce overhead of slub_debug slub: Add method to verify memory is not freed slub: Enable backtrace for create/delete points slab allocators: Provide generic description of alignment defines slab, slub, slob: Unify alignment definition slob/lockdep: Fix gfp flags passed to lockdep
2011-07-21treewide: fix potentially dangerous trailing ';' in #defined values/expressionsPhil Carmody1-1/+1
All these are instances of #define NAME value; or #define NAME(params_opt) value; These of course fail to build when used in contexts like if(foo $OP NAME) while(bar $OP NAME) and may silently generate the wrong code in contexts such as foo = NAME + 1; /* foo = value; + 1; */ bar = NAME - 1; /* bar = value; - 1; */ baz = NAME & quux; /* baz = value; & quux; */ Reported on comp.lang.c, Message-ID: <ab0d55fe-25e5-482b-811e-c475aa6065c3@c29g2000yqd.googlegroups.com> Initial analysis of the dangers provided by Keith Thompson in that thread. There are many more instances of more complicated macros having unnecessary trailing semicolons, but this pile seems to be all of the cases of simple values suffering from the problem. (Thus things that are likely to be found in one of the contexts above, more complicated ones aren't.) Signed-off-by: Phil Carmody <ext-phil.2.carmody@nokia.com> Signed-off-by: Jiri Kosina <jkosina@suse.cz>
2011-07-18slub: disable interrupts in cmpxchg_double_slab when falling back to pagelockChristoph Lameter1-4/+45
Split cmpxchg_double_slab into two functions. One for the case where we know that interrupts are disabled (and therefore the fallback does not need to disable interrupts) and one for the other cases where fallback will also disable interrupts. This fixes the issue that __slab_free called cmpxchg_double_slab in some scenarios without disabling interrupts. Tested-by: Hugh Dickins <hughd@google.com> Signed-off-by: Christoph Lameter <cl@linux.com> Signed-off-by: Pekka Enberg <penberg@kernel.org>
2011-07-07SLUB: Fix missing <linux/stacktrace.h> includePekka Enberg1-0/+1
This fixes the following build breakage commit d6543e3 ("slub: Enable backtrace for create/delete points"): CC mm/slub.o mm/slub.c: In function ‘set_track’: mm/slub.c:428: error: storage size of ‘trace’ isn’t known mm/slub.c:435: error: implicit declaration of function ‘save_stack_trace’ mm/slub.c:428: warning: unused variable ‘trace’ make[1]: *** [mm/slub.o] Error 1 make: *** [mm/slub.o] Error 2 Signed-off-by: Pekka Enberg <penberg@kernel.org>
2011-07-07slub: reduce overhead of slub_debugMarcin Slusarz1-2/+34
slub checks for poison one byte by one, which is highly inefficient and shows up frequently as a highest cpu-eater in perf top. Joining reads gives nice speedup: (Compiling some project with different options) make -j12 make clean slub_debug disabled: 1m 27s 1.2 s slub_debug enabled: 1m 46s 7.6 s slub_debug enabled + this patch: 1m 33s 3.2 s check_bytes still shows up high, but not always at the top. Signed-off-by: Marcin Slusarz <marcin.slusarz@gmail.com> Cc: Christoph Lameter <cl@linux-foundation.org> Cc: Pekka Enberg <penberg@kernel.org> Cc: Matt Mackall <mpm@selenic.com> Cc: linux-mm@kvack.org Signed-off-by: Pekka Enberg <penberg@kernel.org>
2011-07-07slub: Add method to verify memory is not freedBen Greear1-0/+36
This is for tracking down suspect memory usage. Acked-by: Christoph Lameter <cl@linux.com> Signed-off-by: Ben Greear <greearb@candelatech.com> Signed-off-by: Pekka Enberg <penberg@kernel.org>
2011-07-07slub: Enable backtrace for create/delete pointsBen Greear1-0/+32
This patch attempts to grab a backtrace for the creation and deletion points of the slub object. When a fault is detected, we can then get a better idea of where the item was deleted. Example output from debugging some funky nfs/rpc behaviour: ============================================================================= BUG kmalloc-64: Object is on free-list ----------------------------------------------------------------------------- INFO: Allocated in rpcb_getport_async+0x39c/0x5a5 [sunrpc] age=381 cpu=3 pid=3750 __slab_alloc+0x348/0x3ba kmem_cache_alloc_trace+0x67/0xe7 rpcb_getport_async+0x39c/0x5a5 [sunrpc] call_bind+0x70/0x75 [sunrpc] __rpc_execute+0x78/0x24b [sunrpc] rpc_execute+0x3d/0x42 [sunrpc] rpc_run_task+0x79/0x81 [sunrpc] rpc_call_sync+0x3f/0x60 [sunrpc] rpc_ping+0x42/0x58 [sunrpc] rpc_create+0x4aa/0x527 [sunrpc] nfs_create_rpc_client+0xb1/0xf6 [nfs] nfs_init_client+0x3b/0x7d [nfs] nfs_get_client+0x453/0x5ab [nfs] nfs_create_server+0x10b/0x437 [nfs] nfs_fs_mount+0x4ca/0x708 [nfs] mount_fs+0x6b/0x152 INFO: Freed in rpcb_map_release+0x3f/0x44 [sunrpc] age=30 cpu=2 pid=29049 __slab_free+0x57/0x150 kfree+0x107/0x13a rpcb_map_release+0x3f/0x44 [sunrpc] rpc_release_calldata+0x12/0x14 [sunrpc] rpc_free_task+0x59/0x61 [sunrpc] rpc_final_put_task+0x82/0x8a [sunrpc] __rpc_execute+0x23c/0x24b [sunrpc] rpc_async_schedule+0x10/0x12 [sunrpc] process_one_work+0x230/0x41d worker_thread+0x133/0x217 kthread+0x7d/0x85 kernel_thread_helper+0x4/0x10 INFO: Slab 0xffffea00029aa470 objects=20 used=9 fp=0xffff8800be7830d8 flags=0x20000000004081 INFO: Object 0xffff8800be7830d8 @offset=4312 fp=0xffff8800be7827a8 Bytes b4 0xffff8800be7830c8: 87 a8 96 00 01 00 00 00 5a 5a 5a 5a 5a 5a 5a 5a .�......ZZZZZZZZ Object 0xffff8800be7830d8: 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b kkkkkkkkkkkkkkkk Object 0xffff8800be7830e8: 6b 6b 6b 6b 01 08 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b kkkk..kkkkkkkkkk Object 0xffff8800be7830f8: 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b kkkkkkkkkkkkkkkk Object 0xffff8800be783108: 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b a5 kkkkkkkkkkkkkkk� Redzone 0xffff8800be783118: bb bb bb bb bb bb bb bb ������������� Padding 0xffff8800be783258: 5a 5a 5a 5a 5a 5a 5a 5a ZZZZZZZZ Pid: 29049, comm: kworker/2:2 Not tainted 3.0.0-rc4+ #8 Call Trace: [<ffffffff811055c3>] print_trailer+0x131/0x13a [<ffffffff81105601>] object_err+0x35/0x3e [<ffffffff8110746f>] verify_mem_not_deleted+0x7a/0xb7 [<ffffffffa02851b5>] rpcb_getport_done+0x23/0x126 [sunrpc] [<ffffffffa027d0ba>] rpc_exit_task+0x3f/0x6d [sunrpc] [<ffffffffa027d4ab>] __rpc_execute+0x78/0x24b [sunrpc] [<ffffffffa027d6c0>] ? rpc_execute+0x42/0x42 [sunrpc] [<ffffffffa027d6d0>] rpc_async_schedule+0x10/0x12 [sunrpc] [<ffffffff810611b7>] process_one_work+0x230/0x41d [<ffffffff81061102>] ? process_one_work+0x17b/0x41d [<ffffffff81063613>] worker_thread+0x133/0x217 [<ffffffff810634e0>] ? manage_workers+0x191/0x191 [<ffffffff81066e10>] kthread+0x7d/0x85 [<ffffffff81485924>] kernel_thread_helper+0x4/0x10 [<ffffffff8147eb18>] ? retint_restore_args+0x13/0x13 [<ffffffff81066d93>] ? __init_kthread_worker+0x56/0x56 [<ffffffff81485920>] ? gs_change+0x13/0x13 Acked-by: Christoph Lameter <cl@linux.com> Signed-off-by: Ben Greear <greearb@candelatech.com> Signed-off-by: Pekka Enberg <penberg@kernel.org>
2011-07-02slub: Not necessary to check for empty slab on load_freelistChristoph Lameter1-3/+2
load_freelist is now only branched to only if there are objects available. So no need to check the object variable for NULL. Signed-off-by: Pekka Enberg <penberg@kernel.org>
2011-07-02slub: fast release on full slabChristoph Lameter1-2/+19
Make deactivation occur implicitly while checking out the current freelist. This avoids one cmpxchg operation on a slab that is now fully in use. Signed-off-by: Christoph Lameter <cl@linux.com> Signed-off-by: Pekka Enberg <penberg@kernel.org>
2011-07-02slub: Add statistics for the case that the current slab does not match the nodeChristoph Lameter1-0/+3
Slub reloads the per cpu slab if the page does not satisfy the NUMA condition. Track those reloads since doing so has a performance impact. Signed-off-by: Christoph Lameter <cl@linux.com> Signed-off-by: Pekka Enberg <penberg@kernel.org>
2011-07-02slub: Get rid of the another_slab labelChristoph Lameter1-6/+5
We can avoid deactivate slab in special cases if we do the deactivation of slabs in each code flow that leads to new_slab. Signed-off-by: Christoph Lameter <cl@linux.com> Signed-off-by: Pekka Enberg <penberg@kernel.org>
2011-07-02slub: Avoid disabling interrupts in free slowpathChristoph Lameter1-11/+5
Disabling interrupts can be avoided now. However, list operation still require disabling interrupts since allocations can occur from interrupt contexts and there is no way to perform atomic list operations. The acquition of the list_lock therefore has to disable interrupts as well. Dropping interrupt handling significantly simplifies the slowpath. Signed-off-by: Christoph Lameter <cl@linux.com> Signed-off-by: Pekka Enberg <penberg@kernel.org>
2011-07-02slub: Disable interrupts in free_debug processingChristoph Lameter1-4/+10
We will be calling free_debug_processing with interrupts disabled in some case when the later patches are applied. Some of the functions called by free_debug_processing expect interrupts to be off. Signed-off-by: Christoph Lameter <cl@linux.com> Signed-off-by: Pekka Enberg <penberg@kernel.org>
2011-07-02slub: Invert locking and avoid slab lockChristoph Lameter1-77/+52
Locking slabs is no longer necesary if the arch supports cmpxchg operations and if no debuggin features are used on a slab. If the arch does not support cmpxchg then we fallback to use the slab lock to do a cmpxchg like operation. The patch also changes the lock order. Slab locks are subsumed to the node lock now. With that approach slab_trylocking is no longer necessary. Signed-off-by: Christoph Lameter <cl@linux.com> Signed-off-by: Pekka Enberg <penberg@kernel.org>
2011-07-02slub: Rework allocator fastpathsChristoph Lameter1-129/+280
Rework the allocation paths so that updates of the page freelist, frozen state and number of objects use cmpxchg_double_slab(). Signed-off-by: Christoph Lameter <cl@linux.com> Signed-off-by: Pekka Enberg <penberg@kernel.org>
2011-07-02slub: Pass kmem_cache struct to lock and freeze slabChristoph Lameter1-7/+8
We need more information about the slab for the cmpxchg implementation. Signed-off-by: Christoph Lameter <cl@linux.com> Acked-by: David Rientjes <rientjes@google.com> Signed-off-by: Pekka Enberg <penberg@kernel.org>
2011-07-02slub: explicit list_lock takingChristoph Lameter1-40/+49
The allocator fastpath rework does change the usage of the list_lock. Remove the list_lock processing from the functions that hide them from the critical sections and move them into those critical sections. This in turn simplifies the support functions (no __ variant needed anymore) and simplifies the lock handling on bootstrap. Inline add_partial since it becomes pretty simple. Signed-off-by: Christoph Lameter <cl@linux.com> Signed-off-by: Pekka Enberg <penberg@kernel.org>
2011-07-02slub: Add cmpxchg_double_slab()Christoph Lameter1-5/+60
Add a function that operates on the second doubleword in the page struct and manipulates the object counters, the freelist and the frozen attribute. Signed-off-by: Christoph Lameter <cl@linux.com> Signed-off-by: Pekka Enberg <penberg@kernel.org>
2011-07-02slub: Move page->frozen handling near where the page->freelist handling occursChristoph Lameter1-2/+6
This is necessary because the frozen bit has to be handled in the same cmpxchg_double with the freelist and the counters. Signed-off-by: Christoph Lameter <cl@linux.com> Acked-by: David Rientjes <rientjes@google.com> Signed-off-by: Pekka Enberg <penberg@kernel.org>
2011-07-02slub: Do not use frozen page flag but a bit in the page countersChristoph Lameter1-6/+6
Do not use a page flag for the frozen bit. It needs to be part of the state that is handled with cmpxchg_double(). So use a bit in the counter struct in the page struct for that purpose. Signed-off-by: Christoph Lameter <cl@linux.com> Signed-off-by: Pekka Enberg <penberg@kernel.org>
2011-07-02slub: Push irq disable into allocate_slab()Christoph Lameter1-10/+13
Do the irq handling in allocate_slab() instead of __slab_alloc(). __slab_alloc() is already cluttered and allocate_slab() is already fiddling around with gfp flags. v6->v7: Only increment ORDER_FALLBACK if we get a page during fallback Signed-off-by: Christoph Lameter <cl@linux.com> Signed-off-by: Pekka Enberg <penberg@kernel.org>
2011-06-03slub: always align cpu_slab to honor cmpxchg_double requirementChris Metcalf1-8/+4
On an architecture without CMPXCHG_LOCAL but with DEBUG_VM enabled, the VM_BUG_ON() in __pcpu_double_call_return_bool() will cause an early panic during boot unless we always align cpu_slab properly. In principle we could remove the alignment-testing VM_BUG_ON() for architectures that don't have CMPXCHG_LOCAL, but leaving it in means that new code will tend not to break x86 even if it is introduced on another platform, and it's low cost to require alignment. Acked-by: David Rientjes <rientjes@google.com> Acked-by: Christoph Lameter <cl@linux.com> Signed-off-by: Chris Metcalf <cmetcalf@tilera.com> Signed-off-by: Pekka Enberg <penberg@kernel.org>
2011-05-25slub: remove no-longer used 'unlock_out' labelLinus Torvalds1-1/+0
Commit a71ae47a2cbf ("slub: Fix double bit unlock in debug mode") removed the only goto to this label, resulting in mm/slub.c: In function '__slab_alloc': mm/slub.c:1834: warning: label 'unlock_out' defined but not used fixed trivially by the removal of the label itself too. Reported-by: Stephen Rothwell <sfr@canb.auug.org.au> Cc: Christoph Lameter <cl@linux.com> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2011-05-25slub: Fix double bit unlock in debug modeChristoph Lameter1-1/+2
Commit 442b06bcea23 ("slub: Remove node check in slab_free") added a call to deactivate_slab() in the debug case in __slab_alloc(), which unlocks the current slab used for allocation. Going to the label 'unlock_out' then does it again. Also, in the debug case we do not need all the other processing that the 'unlock_out' path does. We always fall back to the slow path in the debug case. So the tid update is useless. Similarly, ALLOC_SLOWPATH would just be incremented for all allocations. Also a pretty useless thing. So simply restore irq flags and return the object. Signed-off-by: Christoph Lameter <cl@linux.com> Reported-and-bisected-by: James Morris <jmorris@namei.org> Reported-by: Ingo Molnar <mingo@elte.hu> Reported-by: Jens Axboe <jaxboe@fusionio.com> Cc: Pekka Enberg <penberg@kernel.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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