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2011-07-20make sure that nsproxy_cache is initialized early enoughAl Viro2-3/+2
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2011-07-20kill file_permission() completelyAl Viro1-1/+2
convert the last remaining caller to inode_permission() Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2011-07-15Merge branch 'rcu/urgent' of ↵Linus Torvalds2-5/+36
git://git.kernel.org/pub/scm/linux/kernel/git/paulmck/linux-2.6-rcu * 'rcu/urgent' of git://git.kernel.org/pub/scm/linux/kernel/git/paulmck/linux-2.6-rcu: rcu: Prevent RCU callbacks from executing before scheduler initialized
2011-07-15sched: Fix 32bit racePeter Zijlstra1-0/+3
Commit 3fe1698b7fe0 ("sched: Deal with non-atomic min_vruntime reads on 32bit") forgot to initialize min_vruntime_copy which could lead to an infinite while loop in task_waking_fair() under some circumstances (early boot, lucky timing). [ This bug was also reported by others that blamed it on the RCU initialization problems ] Reported-and-tested-by: Bruno Wolff III <bruno@wolff.to> Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Reviewed-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2011-07-13rcu: Prevent RCU callbacks from executing before scheduler initializedPaul E. McKenney2-5/+36
Under some rare but real combinations of configuration parameters, RCU callbacks are posted during early boot that use kernel facilities that are not yet initialized. Therefore, when these callbacks are invoked, hard hangs and crashes ensue. This commit therefore prevents RCU callbacks from being invoked until after the scheduler is fully up and running, as in after multiple tasks have been spawned. It might well turn out that a better approach is to identify the specific RCU callbacks that are causing this problem, but that discussion will wait until such time as someone really needs an RCU callback to be invoked (as opposed to merely registered) during early boot. Reported-by: julie Sullivan <kernelmail.jms@gmail.com> Reported-by: RKK <kulkarni.ravi4@gmail.com> Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Tested-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com> Tested-by: julie Sullivan <kernelmail.jms@gmail.com> Tested-by: RKK <kulkarni.ravi4@gmail.com>
2011-07-12Merge branch 'fixes' of ↵Linus Torvalds1-2/+16
git://git.kernel.org/pub/scm/linux/kernel/git/arm/linux-arm-soc * 'fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/arm/linux-arm-soc: pcmcia: pxa2xx/vpac270: free gpios on exist rather than requesting ARM: pxa/raumfeld: fix device name for codec ak4104 ARM: pxa/raumfeld: display initialisation fixes ARM: pxa/raumfeld: adapt to upcoming hardware change ARM: pxa: fix gpio_to_chip() clash with gpiolib namespace genirq: replace irq_gc_ack() with {set,clr}_bit variants (fwd) arm: mach-vt8500: add forgotten irq_data conversion ARM: pxa168: correct nand pmu setting ARM: pxa910: correct nand pmu setting ARM: pxa: fix PGSR register address calculation
2011-07-07Merge branch 'pm-fixes' of ↵Linus Torvalds1-1/+5
git://git.kernel.org/pub/scm/linux/kernel/git/rafael/suspend-2.6 * 'pm-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/rafael/suspend-2.6: PM / Hibernate: Fix free_unnecessary_pages()
2011-07-07Merge branches 'core-urgent-for-linus', 'perf-urgent-for-linus' and ↵Linus Torvalds2-11/+12
'sched-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip * 'core-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip: debugobjects: Fix boot crash when kmemleak and debugobjects enabled * 'perf-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip: jump_label: Fix jump_label update for modules oprofile, x86: Fix race in nmi handler while starting counters * 'sched-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip: sched: Disable (revert) SCHED_LOAD_SCALE increase sched, cgroups: Fix MIN_SHARES on 64-bit boxen
2011-07-07genirq: replace irq_gc_ack() with {set,clr}_bit variants (fwd)Simon Guinot1-2/+16
This fixes a regression introduced by e59347a "arm: orion: Use generic irq chip". Depending on the device, interrupts acknowledgement is done by setting or by clearing a dedicated register. Replace irq_gc_ack() with some {set,clr}_bit variants allows to handle both cases. Note that this patch affects the following SoCs: Davinci, Samsung and Orion. Except for this last, the change is minor: irq_gc_ack() is just renamed into irq_gc_ack_set_bit(). For the Orion SoCs, the edge GPIO interrupts support is currently broken. irq_gc_ack() try to acknowledge a such interrupt by setting the corresponding cause register bit. The Orion GPIO device expect the opposite. To fix this issue, the irq_gc_ack_clr_bit() variant is used. Tested on Network Space v2. Reported-by: Joey Oravec <joravec@drewtech.com> Signed-off-by: Simon Guinot <sguinot@lacie.com> Signed-off-by: Arnd Bergmann <arnd@arndb.de>
2011-07-06PM / Hibernate: Fix free_unnecessary_pages()Rafael J. Wysocki1-1/+5
There is a bug in free_unnecessary_pages() that causes it to attempt to free too many pages in some cases, which triggers the BUG_ON() in memory_bm_clear_bit() for copy_bm. Namely, if count_data_pages() is initially greater than alloc_normal, we get to_free_normal equal to 0 and "save" greater from 0. In that case, if the sum of "save" and count_highmem_pages() is greater than alloc_highmem, we subtract a positive number from to_free_normal. Hence, since to_free_normal was 0 before the subtraction and is an unsigned int, the result is converted to a huge positive number that is used as the number of pages to free. Fix this bug by checking if to_free_normal is actually greater than or equal to the number we're going to subtract from it. Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl> Reported-and-tested-by: Matthew Garrett <mjg@redhat.com> Cc: stable@kernel.org
2011-07-06resource: ability to resize an allocated resourceRam Pai1-18/+98
Provides the ability to resize a resource that is already allocated. This functionality is put in place to support reallocation needs of pci resources. Signed-off-by: Ram Pai <linuxram@us.ibm.com> Acked-by: Jesse Barnes <jbarnes@virtuousgeek.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2011-07-01sched, cgroups: Fix MIN_SHARES on 64-bit boxenMike Galbraith1-6/+3
Commit c8b28116 ("sched: Increase SCHED_LOAD_SCALE resolution") intended to have no user-visible effect, but allows setting cpu.shares to < MIN_SHARES, which the user then sees. Signed-off-by: Mike Galbraith <efault@gmx.de> Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Cc: Nikhil Rao <ncrao@google.com> Link: http://lkml.kernel.org/r/1307192600.8618.3.camel@marge.simson.net Signed-off-by: Ingo Molnar <mingo@elte.hu>
2011-06-29jump_label: Fix jump_label update for modulesXiao Guangrong1-5/+9
The jump labels entries for modules do not stop at __stop__jump_table, but after mod->jump_entries + mod_num_jump_entries. By checking the wrong end point, module trace events never get enabled. Cc: Ingo Molnar <mingo@elte.hu> Acked-by: Jason Baron <jbaron@redhat.com> Tested-by: Avi Kivity <avi@redhat.com> Tested-by: Johannes Berg <johannes@sipsolutions.net> Signed-off-by: Xiao Guangrong <xiaoguangrong@cn.fujitsu.com> Link: http://lkml.kernel.org/r/4E00038B.2060404@cn.fujitsu.com Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
2011-06-27taskstats: don't allow duplicate entries in listener modeVasiliy Kulikov1-3/+12
Currently a single process may register exit handlers unlimited times. It may lead to a bloated listeners chain and very slow process terminations. Eg after 10KK sent TASKSTATS_CMD_ATTR_REGISTER_CPUMASKs ~300 Mb of kernel memory is stolen for the handlers chain and "time id" shows 2-7 seconds instead of normal 0.003. It makes it possible to exhaust all kernel memory and to eat much of CPU time by triggerring numerous exits on a single CPU. The patch limits the number of times a single process may register itself on a single CPU to one. One little issue is kept unfixed - as taskstats_exit() is called before exit_files() in do_exit(), the orphaned listener entry (if it was not explicitly deregistered) is kept until the next someone's exit() and implicit deregistration in send_cpu_listeners(). So, if a process registered itself as a listener exits and the next spawned process gets the same pid, it would inherit taskstats attributes. Signed-off-by: Vasiliy Kulikov <segooon@gmail.com> Cc: Balbir Singh <bsingharora@gmail.com> Cc: <stable@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2011-06-25Merge branch 'timer-fixes-for-linus' of ↵Linus Torvalds1-70/+88
git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip * 'timer-fixes-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip: rtc: vt8500: Fix build error & cleanup rtc_class_ops->update_irq_enable() alarmtimers: Return -ENOTSUPP if no RTC device is present alarmtimers: Handle late rtc module loading
2011-06-21alarmtimers: Return -ENOTSUPP if no RTC device is presentJohn Stultz1-1/+22
Toralf Förster and Richard Weinberger noted that if there is no RTC device, the alarm timers core prints out an annoying "ALARM timers will not wake from suspend" message. This warning has been removed in a previous patch, however the issue still remains: The original idea was to support alarm timers even if there was no rtc device, as long as the system didn't go into suspend. However, after further consideration, communicating to the application that alarmtimers are not fully functional seems like the better solution. So this patch makes it so we return -ENOTSUPP to any posix _ALARM clockid calls if there is no backing RTC device on the system. Further this changes the behavior where when there is no rtc device we will check for one on clock_getres, clock_gettime, timer_create, and timer_nsleep instead of on suspend. CC: Toralf Förster <toralf.foerster@gmx.de> CC: Richard Weinberger <richard@nod.at CC: Peter Zijlstra <peterz@infradead.org> CC: Thomas Gleixner <tglx@linutronix.de> Reported-by: Toralf Förster <toralf.foerster@gmx.de> Reported by: Richard Weinberger <richard@nod.at> Signed-off-by: John Stultz <john.stultz@linaro.org>
2011-06-21alarmtimers: Handle late rtc module loadingJohn Stultz1-70/+67
The alarmtimers code currently picks a rtc device to use at late init time. However, if your rtc driver is loaded as a module, it may be registered after the alarmtimers late init code, leaving the alarmtimers nonfunctional. This patch moves the the rtcdevice selection to when we actually try to use it, allowing us to make use of rtc modules that may have been loaded at any point since bootup. CC: Thomas Gleixner <tglx@linutronix.de> CC: Meelis Roos <mroos@ut.ee> Reported-by: Meelis Roos <mroos@ut.ee> Signed-off-by: John Stultz <john.stultz@linaro.org>
2011-06-21PM: Free memory bitmaps if opening /dev/snapshot failsMichal Kubecek1-1/+3
When opening /dev/snapshot device, snapshot_open() creates memory bitmaps which are freed in snapshot_release(). But if any of the callbacks called by pm_notifier_call_chain() returns NOTIFY_BAD, open() fails, snapshot_release() is never called and bitmaps are not freed. Next attempt to open /dev/snapshot then triggers BUG_ON() check in create_basic_memory_bitmaps(). This happens e.g. when vmwatchdog module is active on s390x. Signed-off-by: Michal Kubecek <mkubecek@suse.cz> Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl> Cc: stable@kernel.org
2011-06-19Merge branches 'perf-urgent-for-linus', 'sched-urgent-for-linus', ↵Linus Torvalds3-19/+15
'timers-urgent-for-linus' and 'x86-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip * 'perf-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip: tools/perf: Fix static build of perf tool tracing: Fix regression in printk_formats file * 'sched-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip: generic-ipi: Fix kexec boot crash by initializing call_single_queue before enabling interrupts * 'timers-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip: clocksource: Make watchdog robust vs. interruption timerfd: Fix wakeup of processes when timer is cancelled on clock change * 'x86-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip: x86, MAINTAINERS: Add x86 MCE people x86, efi: Do not reserve boot services regions within reserved areas
2011-06-19Merge branch 'core-urgent-for-linus' of ↵Linus Torvalds5-402/+461
git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip * 'core-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip: rcu: Move RCU_BOOST #ifdefs to header file rcu: use softirq instead of kthreads except when RCU_BOOST=y rcu: Use softirq to address performance regression rcu: Simplify curing of load woes
2011-06-17KEYS/DNS: Fix ____call_usermodehelper() to not lose the session keyringDavid Howells1-7/+9
____call_usermodehelper() now erases any credentials set by the subprocess_inf::init() function. The problem is that commit 17f60a7da150 ("capabilites: allow the application of capability limits to usermode helpers") creates and commits new credentials with prepare_kernel_cred() after the call to the init() function. This wipes all keyrings after umh_keys_init() is called. The best way to deal with this is to put the init() call just prior to the commit_creds() call, and pass the cred pointer to init(). That means that umh_keys_init() and suchlike can modify the credentials _before_ they are published and potentially in use by the rest of the system. This prevents request_key() from working as it is prevented from passing the session keyring it set up with the authorisation token to /sbin/request-key, and so the latter can't assume the authority to instantiate the key. This causes the in-kernel DNS resolver to fail with ENOKEY unconditionally. Signed-off-by: David Howells <dhowells@redhat.com> Acked-by: Eric Paris <eparis@redhat.com> Tested-by: Jeff Layton <jlayton@redhat.com> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2011-06-17generic-ipi: Fix kexec boot crash by initializing call_single_queue before ↵Takao Indoh1-4/+1
enabling interrupts There is a problem that kdump(2nd kernel) sometimes hangs up due to a pending IPI from 1st kernel. Kernel panic occurs because IPI comes before call_single_queue is initialized. To fix the crash, rename init_call_single_data() to call_function_init() and call it in start_kernel() so that call_single_queue can be initialized before enabling interrupts. The details of the crash are: (1) 2nd kernel boots up (2) A pending IPI from 1st kernel comes when irqs are first enabled in start_kernel(). (3) Kernel tries to handle the interrupt, but call_single_queue is not initialized yet at this point. As a result, in the generic_smp_call_function_single_interrupt(), NULL pointer dereference occurs when list_replace_init() tries to access &q->list.next. Therefore this patch changes the name of init_call_single_data() to call_function_init() and calls it before local_irq_enable() in start_kernel(). Signed-off-by: Takao Indoh <indou.takao@jp.fujitsu.com> Reviewed-by: WANG Cong <xiyou.wangcong@gmail.com> Acked-by: Neil Horman <nhorman@tuxdriver.com> Acked-by: Vivek Goyal <vgoyal@redhat.com> Acked-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Cc: Milton Miller <miltonm@bga.com> Cc: Jens Axboe <axboe@kernel.dk> Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Cc: kexec@lists.infradead.org Link: http://lkml.kernel.org/r/D6CBEE2F420741indou.takao@jp.fujitsu.com Signed-off-by: Ingo Molnar <mingo@elte.hu>
2011-06-16rcu: Move RCU_BOOST #ifdefs to header filePaul E. McKenney3-382/+390
The commit "use softirq instead of kthreads except when RCU_BOOST=y" just applied #ifdef in place. This commit is a cleanup that moves the newly #ifdef'ed code to the header file kernel/rcutree_plugin.h. Signed-off-by: Paul E. McKenney <paul.mckenney@linaro.org> Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
2011-06-16clocksource: Make watchdog robust vs. interruptionThomas Gleixner1-11/+13
The clocksource watchdog code is interruptible and it has been observed that this can trigger false positives which disable the TSC. The reason is that an interrupt storm or a long running interrupt handler between the read of the watchdog source and the read of the TSC brings the two far enough apart that the delta is larger than the unstable treshold. Move both reads into a short interrupt disabled region to avoid that. Reported-and-tested-by: Vernon Mauery <vernux@us.ibm.com> Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Cc: stable@kernel.org
2011-06-15rcu: use softirq instead of kthreads except when RCU_BOOST=yPaul E. McKenney4-41/+99
This patch #ifdefs RCU kthreads out of the kernel unless RCU_BOOST=y, thus eliminating context-switch overhead if RCU priority boosting has not been configured. Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
2011-06-15Merge branch 'sched-urgent-for-linus' of ↵Linus Torvalds1-1/+5
git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip * 'sched-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip: sched: Check if lowest_mask is initialized in find_lowest_rq() sched: Fix need_resched() when checking peempt
2011-06-15gcov: disable CONFIG_CONSTRUCTORS when not needed by CONFIG_GCOV_KERNELJosh Triplett1-1/+2
CONFIG_CONSTRUCTORS controls support for running constructor functions at kernel init time. According to commit b99b87f70c7785ab ("kernel: constructor support"), gcov (CONFIG_GCOV_KERNEL) needs this. However, CONFIG_CONSTRUCTORS currently defaults to y, with no option to disable it, and CONFIG_GCOV_KERNEL depends on it. Instead, default it to n and have CONFIG_GCOV_KERNEL select it, so that the normal case of CONFIG_GCOV_KERNEL=n will result in CONFIG_CONSTRUCTORS=n. Observed in the short list of =y values in a minimal kernel configuration. Signed-off-by: Josh Triplett <josh@joshtriplett.org> Acked-by: WANG Cong <xiyou.wangcong@gmail.com> Acked-by: Peter Oberparleiter <peter.oberparleiter@de.ibm.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2011-06-15memcg: clear mm->owner when last possible owner leavesKAMEZAWA Hiroyuki1-16/+15
The following crash was reported: > Call Trace: > [<ffffffff81139792>] mem_cgroup_from_task+0x15/0x17 > [<ffffffff8113a75a>] __mem_cgroup_try_charge+0x148/0x4b4 > [<ffffffff810493f3>] ? need_resched+0x23/0x2d > [<ffffffff814cbf43>] ? preempt_schedule+0x46/0x4f > [<ffffffff8113afe8>] mem_cgroup_charge_common+0x9a/0xce > [<ffffffff8113b6d1>] mem_cgroup_newpage_charge+0x5d/0x5f > [<ffffffff81134024>] khugepaged+0x5da/0xfaf > [<ffffffff81078ea0>] ? __init_waitqueue_head+0x4b/0x4b > [<ffffffff81133a4a>] ? add_mm_counter.constprop.5+0x13/0x13 > [<ffffffff81078625>] kthread+0xa8/0xb0 > [<ffffffff814d13e8>] ? sub_preempt_count+0xa1/0xb4 > [<ffffffff814d5664>] kernel_thread_helper+0x4/0x10 > [<ffffffff814ce858>] ? retint_restore_args+0x13/0x13 > [<ffffffff8107857d>] ? __init_kthread_worker+0x5a/0x5a What happens is that khugepaged tries to charge a huge page against an mm whose last possible owner has already exited, and the memory controller crashes when the stale mm->owner is used to look up the cgroup to charge. mm->owner has never been set to NULL with the last owner going away, but nobody cared until khugepaged came along. Even then it wasn't a problem because the final mmput() on an mm was forced to acquire and release mmap_sem in write-mode, preventing an exiting owner to go away while the mmap_sem was held, and until "692e0b3 mm: thp: optimize memcg charge in khugepaged", the memory cgroup charge was protected by mmap_sem in read-mode. Instead of going back to relying on the mmap_sem to enforce lifetime of a task, this patch ensures that mm->owner is properly set to NULL when the last possible owner is exiting, which the memory controller can handle just fine. [akpm@linux-foundation.org: tweak comments] Signed-off-by: Hugh Dickins <hughd@google.com> Signed-off-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Signed-off-by: Johannes Weiner <hannes@cmpxchg.org> Reported-by: Hugh Dickins <hughd@google.com> Reported-by: Dave Jones <davej@redhat.com> Reviewed-by: Andrea Arcangeli <aarcange@redhat.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2011-06-15sched: Check if lowest_mask is initialized in find_lowest_rq()Steven Rostedt1-0/+4
On system boot up, the lowest_mask is initialized with an early_initcall(). But RT tasks may wake up on other early_initcall() callers before the lowest_mask is initialized, causing a system crash. Commit "d72bce0e67 rcu: Cure load woes" was the first commit to wake up RT tasks in early init. Before this commit this bug should not happen. Reported-by: Andrew Theurer <habanero@linux.vnet.ibm.com> Tested-by: Andrew Theurer <habanero@linux.vnet.ibm.com> Tested-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Signed-off-by: Steven Rostedt <rostedt@goodmis.org> Acked-by: Peter Zijlstra <peterz@infradead.org> Link: http://lkml.kernel.org/r/20110614223657.824872966@goodmis.org Signed-off-by: Ingo Molnar <mingo@elte.hu>
2011-06-15sched: Fix need_resched() when checking peemptHillf Danton1-1/+1
The RT preempt check tests the wrong task if NEED_RESCHED is set. It currently checks the local CPU task. It is supposed to check the task that is running on the runqueue we are about to wake another task on. Signed-off-by: Hillf Danton <dhillf@gmail.com> Reviewed-by: Yong Zhang <yong.zhang0@gmail.com> Signed-off-by: Steven Rostedt <rostedt@goodmis.org> Link: http://lkml.kernel.org/r/20110614223657.450239027@goodmis.org Signed-off-by: Ingo Molnar <mingo@elte.hu>
2011-06-14signal.c: fix kernel-doc notationRandy Dunlap1-1/+1
Fix kernel-doc warnings in signal.c: Warning(kernel/signal.c:2374): No description found for parameter 'nset' Warning(kernel/signal.c:2374): Excess function parameter 'set' description in 'sys_rt_sigprocmask' Signed-off-by: Randy Dunlap <randy.dunlap@oracle.com> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2011-06-14rcu: Use softirq to address performance regressionShaohua Li4-5/+30
Commit a26ac2455ffcf3(rcu: move TREE_RCU from softirq to kthread) introduced performance regression. In an AIM7 test, this commit degraded performance by about 40%. The commit runs rcu callbacks in a kthread instead of softirq. We observed high rate of context switch which is caused by this. Out test system has 64 CPUs and HZ is 1000, so we saw more than 64k context switch per second which is caused by RCU's per-CPU kthread. A trace showed that most of the time the RCU per-CPU kthread doesn't actually handle any callbacks, but instead just does a very small amount of work handling grace periods. This means that RCU's per-CPU kthreads are making the scheduler do quite a bit of work in order to allow a very small amount of RCU-related processing to be done. Alex Shi's analysis determined that this slowdown is due to lock contention within the scheduler. Unfortunately, as Peter Zijlstra points out, the scheduler's real-time semantics require global action, which means that this contention is inherent in real-time scheduling. (Yes, perhaps someone will come up with a workaround -- otherwise, -rt is not going to do well on large SMP systems -- but this patch will work around this issue in the meantime. And "the meantime" might well be forever.) This patch therefore re-introduces softirq processing to RCU, but only for core RCU work. RCU callbacks are still executed in kthread context, so that only a small amount of RCU work runs in softirq context in the common case. This should minimize ksoftirqd execution, allowing us to skip boosting of ksoftirqd for CONFIG_RCU_BOOST=y kernels. Signed-off-by: Shaohua Li <shaohua.li@intel.com> Tested-by: "Alex,Shi" <alex.shi@intel.com> Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
2011-06-14rcu: Simplify curing of load woesPaul E. McKenney2-54/+22
Make the functions creating the kthreads wake them up. Leverage the fact that the per-node and boost kthreads can run anywhere, thus dispensing with the need to wake them up once the incoming CPU has gone fully online. Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Tested-by: Daniel J Blueman <daniel.blueman@gmail.com>
2011-06-13Merge branch 'perf-urgent-for-linus' of ↵Linus Torvalds2-3/+14
git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip * 'perf-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip: ftrace: Revert 8ab2b7efd ftrace: Remove unnecessary disabling of irqs kprobes/trace: Fix kprobe selftest for gcc 4.6 ftrace: Fix possible undefined return code oprofile, dcookies: Fix possible circular locking dependency oprofile: Fix locking dependency in sync_start() oprofile: Free potentially owned tasks in case of errors oprofile, x86: Add comments to IBS LVT offset initialization
2011-06-10genirq: Prevent potential NULL dereference in irq_set_irq_wake()Jesper Juhl1-0/+3
In kernel/irq/manage.c::irq_set_irq_wake() we call irq_get_desc_buslock() which may return NULL, but the code dereferences the result unconditionally. irq_set_irq_wake() has lots of callers - I checked a few and I couldn't find anything that guarantees that they won't call it with some input that will cause irq_get_desc_buslock() to return NULL, so I think it's a good thing to test and -EINVAL was the most sane error code in this situation that I could think of. Not all callers test the return value of irq_set_irq_wake(), but those that do take != 0 to mean error as far as I can see, so they should be fine. I guess those that don't test actually should, but that's a different issue. Signed-off-by: Jesper Juhl <jj@chaosbits.net> Link: http://lkml.kernel.org/r/alpine.LNX.2.00.1106092300360.17868@swampdragon.chaosbits.net Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
2011-06-09tracing: Fix regression in printk_formats fileSteven Rostedt1-4/+1
The fix to fix the printk_formats of modules broke the printk_formats of trace_printks in the kernel. The update of what to show via the seq_file was only updated if the passed in fmt was NULL, which happens only on the first iteration. The result was showing the first format every time instead of iterating through the available formats. Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
2011-06-08Merge branch 'perf-urgent-for-linus' of ↵Linus Torvalds2-18/+10
git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip * 'perf-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip: perf: Fix comments in include/linux/perf_event.h perf: Comment /proc/sys/kernel/perf_event_paranoid to be part of user ABI perf python: Fix argument name list of read_on_cpu() perf evlist: Don't die if sample_{id_all|type} is invalid perf python: Use exception to propagate errors perf evlist: Remove dependency on debug routines perf, cgroups: Fix up for new API
2011-06-07Merge branch 'irq-urgent-for-linus' of ↵Linus Torvalds4-25/+50
git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip * 'irq-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip: genirq: Ensure we locate the passed IRQ in irq_alloc_descs() genirq: Fix descriptor init on non-sparse IRQs irq: Handle spurios irq detection for threaded irqs genirq: Print threaded handler in spurious debug output
2011-06-07Merge branch 'sched-urgent-for-linus' of ↵Linus Torvalds2-10/+25
git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip * 'sched-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip: sched: Fix/clarify set_task_cpu() locking rules lockdep: Fix lock_is_held() on recursion sched: Fix schedstat.nr_wakeups_migrate sched: Fix cross-cpu clock sync on remote wakeups
2011-06-07ftrace: Revert 8ab2b7efd ftrace: Remove unnecessary disabling of irqsSteven Rostedt1-0/+7
Revert the commit that removed the disabling of interrupts around the initial modifying of mcount callers to nops, and update the comment. The original comment was outdated and stated that the interrupts were being disabled to prevent kstop machine, which was required with the old ftrace daemon, but was no longer the case. What the comment failed to mention was that interrupts needed to be disabled to keep interrupts from preempting the modifying of the code and then executing the code that was partially modified. Revert the commit and update the comment. Reported-by: Richard W.M. Jones <rjones@redhat.com> Tested-by: Richard W.M. Jones <rjones@redhat.com> Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
2011-06-07kprobes/trace: Fix kprobe selftest for gcc 4.6Steven Rostedt1-2/+6
With gcc 4.6, the self test kprobe function: kprobe_trace_selftest_target() is optimized such that kallsyms does not list it. The kprobes test uses this function to insert a probe and test it. But it will fail the test if the function is not listed in kallsyms. Adding a __used annotation keeps the symbol in the kallsyms table. Suggested-by: David Daney <ddaney@caviumnetworks.com> Cc: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com> Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
2011-06-07sched: Fix/clarify set_task_cpu() locking rulesPeter Zijlstra1-5/+16
Sergey reported a CONFIG_PROVE_RCU warning in push_rt_task where set_task_cpu() was called with both relevant rq->locks held, which should be sufficient for running tasks since holding its rq->lock will serialize against sched_move_task(). Update the comments and fix the task_group() lockdep test. Reported-and-tested-by: Sergey Senozhatsky <sergey.senozhatsky@gmail.com> Cc: Oleg Nesterov <oleg@redhat.com> Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Link: http://lkml.kernel.org/r/1307115427.2353.3456.camel@twins Signed-off-by: Ingo Molnar <mingo@elte.hu>
2011-06-07lockdep: Fix lock_is_held() on recursionPeter Zijlstra1-1/+1
The main lock_is_held() user is lockdep_assert_held(), avoid false assertions in lockdep_off() sections by unconditionally reporting the lock is taken. [ the reason this is important is a lockdep_assert_held() in ttwu() which triggers a warning under lockdep_off() as in printk() which can trigger another wakeup and lock up due to spinlock recursion, as reported and heroically debugged by Arne Jansen ] Reported-and-tested-by: Arne Jansen <lists@die-jansens.de> Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: <stable@kernel.org> Link: http://lkml.kernel.org/r/1307398759.2497.966.camel@laptop Signed-off-by: Ingo Molnar <mingo@elte.hu>
2011-06-06ftrace: Fix possible undefined return codeGuoWen Li1-1/+1
kernel/trace/ftrace.c: In function 'ftrace_regex_write.clone.15': kernel/trace/ftrace.c:2743:6: warning: 'ret' may be used uninitialized in this function Signed-off-by: GuoWen Li <guowen.li.linux@gmail.com> Link: http://lkml.kernel.org/r/201106011918.47939.guowen.li.linux@gmail.com Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
2011-06-04perf: Comment /proc/sys/kernel/perf_event_paranoid to be part of user ABIVince Weaver1-0/+6
Turns out that distro packages use this file as an indicator of the perf event subsystem - this is easier to check for from scripts than the existence of the system call. This is easy enough to keep around for the kernel, so add a comment to make sure it stays so. Signed-off-by: Vince Weaver <vweaver1@eecs.utk.edu> Cc: David Ahern <dsahern@gmail.com> Cc: Peter Zijlstra <a.p.zijlstra@chello.nl> Cc: paulus@samba.org Cc: acme@redhat.com Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Andrew Morton <akpm@linux-foundation.org> Link: http://lkml.kernel.org/r/alpine.DEB.2.00.1106031751170.29381@cl320.eecs.utk.edu Signed-off-by: Ingo Molnar <mingo@elte.hu>
2011-06-04Merge branch 'perf/urgent' of ↵Ingo Molnar20-233/+337
git://git.kernel.org/pub/scm/linux/kernel/git/acme/linux into perf/urgent
2011-06-03timers: Consider slack value in mod_timer()Sebastian Andrzej Siewior1-8/+7
There is an optimization which does not update the timer if the timer was pending and the expiration time was unchanged. Since commit 3bbb9ec9 ("timers: Introduce the concept of timer slack for legacy timers") this optimization is no longer applied for timers where the expiration time got extended due to the slack value. So we need to check again after the expiration time might have been updated. [ tglx: Made it a single check by applying slack first and sorting out the slack = 0 value (all timeouts < 256 jiffies) early ] Signed-off-by: Sebastian Andrzej Siewior <sebastian@breakpoint.cc> Link: http://lkml.kernel.org/r/20110521105828.GA29442@Chamillionaire.breakpoint.cc Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
2011-06-03genirq: Ensure we locate the passed IRQ in irq_alloc_descs()Mark Brown1-0/+6
When irq_alloc_descs() is called with no base IRQ specified then it will search for a range of IRQs starting from a specified base address. In the case where an IRQ is specified it still does this search in order to ensure that none of the requested range is already allocated and it still uses the from parameter to specify the base for the search. This means that in the case where a base is specified but from is zero (which is reasonable as any IRQ number is in the range specified by a zero from) the function will get confused and try to allocate the first suitably sized block of free IRQs it finds. Instead use a specified IRQ as the base address for the search, and insist that any from that is specified can support that IRQ. Signed-off-by: Mark Brown <broonie@opensource.wolfsonmicro.com> Link: http://lkml.kernel.org/r/1307037313-15733-1-git-send-email-broonie@opensource.wolfsonmicro.com Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
2011-06-03genirq: Fix descriptor init on non-sparse IRQsLinus Walleij1-5/+3
The genirq changes are initializing descriptors for sparse IRQs quite differently from how non-sparse (stacked?) IRQs are initialized, with the effect that on my platform all IRQs are default-disabled on sparse IRQs and default-enabled if non-sparse IRQs are used, crashing some GPIO driver. Fix this by refactoring the non-sparse IRQs to use the same descriptor init function as the sparse IRQs. Signed-off: Linus Walleij <linus.walleij@linaro.org> Link: http://lkml.kernel.org/r/1306858479-16622-1-git-send-email-linus.walleij@stericsson.com Cc: stable@kernel.org # 2.6.39 Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
2011-06-03irq: Handle spurios irq detection for threaded irqsSebastian Andrzej Siewior3-16/+36
The detection of spurios interrupts is currently limited to first level handler. In force-threaded mode we never notice if the threaded irq does not feel responsible. This patch catches the return value of the threaded handler and forwards it to the spurious detector. If the primary handler returns only IRQ_WAKE_THREAD then the spourious detector ignores it because it gets called again from the threaded handler. [ tglx: Report the erroneous return value early and bail out ] Signed-off-by: Sebastian Andrzej Siewior <sebastian@breakpoint.cc> Link: http://lkml.kernel.org/r/1306824972-27067-2-git-send-email-sebastian@breakpoint.cc Signed-off-by: Thomas Gleixner <tglx@linutronix.de>