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* workqueue: fix race condition in schedule_on_each_cpu()Tejun Heo2009-11-17
| | | | | | | | | | | | | | | | | | | | Commit 65a64464349883891e21e74af16c05d6e1eeb4e9 ("HWPOISON: Allow schedule_on_each_cpu() from keventd") which allows schedule_on_each_cpu() to be called from keventd added a race condition. schedule_on_each_cpu() may race with cpu hotplug and end up executing the function twice on a cpu. Fix it by moving direct execution into the section protected with get/put_online_cpus(). While at it, update code such that direct execution is done after works have been scheduled for all other cpus and drop unnecessary cpu != orig test from flush loop. Signed-off-by: Tejun Heo <tj@kernel.org> Cc: Andi Kleen <ak@linux.intel.com> Acked-by: Oleg Nesterov <oleg@redhat.com> Cc: Ingo Molnar <mingo@redhat.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* Merge branch 'core-fixes-for-linus' of ↵Linus Torvalds2009-11-11
|\ | | | | | | | | | | | | | | | | | | git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip * 'core-fixes-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip: highmem: Fix debug_kmap_atomic() to also handle KM_IRQ_PTE, KM_NMI, and KM_NMI_PTE highmem: Fix race in debug_kmap_atomic() which could cause warn_count to underflow rcu: Fix long-grace-period race between forcing and initialization uids: Prevent tear down race
| * rcu: Fix long-grace-period race between forcing and initializationPaul E. McKenney2009-11-02
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Very long RCU read-side critical sections (50 milliseconds or so) can cause a race between force_quiescent_state() and rcu_start_gp() as follows on kernel builds with multi-level rcu_node hierarchies: 1. CPU 0 calls force_quiescent_state(), sees that there is a grace period in progress, and acquires ->fsqlock. 2. CPU 1 detects the end of the grace period, and so cpu_quiet_msk_finish() sets rsp->completed to rsp->gpnum. This operation is carried out under the root rnp->lock, but CPU 0 has not yet acquired that lock. Note that rsp->signaled is still RCU_SAVE_DYNTICK from the last grace period. 3. CPU 1 calls rcu_start_gp(), but no one wants a new grace period, so it drops the root rnp->lock and returns. 4. CPU 0 acquires the root rnp->lock and picks up rsp->completed and rsp->signaled, then drops rnp->lock. It then enters the RCU_SAVE_DYNTICK leg of the switch statement. 5. CPU 2 invokes call_rcu(), and now needs a new grace period. It calls rcu_start_gp(), which acquires the root rnp->lock, sets rsp->signaled to RCU_GP_INIT (too bad that CPU 0 is already in the RCU_SAVE_DYNTICK leg of the switch statement!) and starts initializing the rcu_node hierarchy. If there are multiple levels to the hierarchy, it will drop the root rnp->lock and initialize the lower levels of the hierarchy. 6. CPU 0 notes that rsp->completed has not changed, which permits both CPU 2 and CPU 0 to try updating it concurrently. If CPU 0's update prevails, later calls to force_quiescent_state() can count old quiescent states against the new grace period, which can in turn result in premature ending of grace periods. Not good. This patch adds an RCU_GP_IDLE state for rsp->signaled that is set initially at boot time and any time a grace period ends. This prevents CPU 0 from getting into the workings of force_quiescent_state() in step 4. Additional locking and checks prevent the concurrent update of rsp->signaled in step 6. Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Cc: laijs@cn.fujitsu.com Cc: dipankar@in.ibm.com Cc: mathieu.desnoyers@polymtl.ca Cc: josh@joshtriplett.org Cc: dvhltc@us.ibm.com Cc: niv@us.ibm.com Cc: peterz@infradead.org Cc: rostedt@goodmis.org Cc: Valdis.Kletnieks@vt.edu Cc: dhowells@redhat.com LKML-Reference: <1256742889199-git-send-email-> Signed-off-by: Ingo Molnar <mingo@elte.hu>
| * uids: Prevent tear down raceThomas Gleixner2009-11-02
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Ingo triggered the following warning: WARNING: at lib/debugobjects.c:255 debug_print_object+0x42/0x50() Hardware name: System Product Name ODEBUG: init active object type: timer_list Modules linked in: Pid: 2619, comm: dmesg Tainted: G W 2.6.32-rc5-tip+ #5298 Call Trace: [<81035443>] warn_slowpath_common+0x6a/0x81 [<8120e483>] ? debug_print_object+0x42/0x50 [<81035498>] warn_slowpath_fmt+0x29/0x2c [<8120e483>] debug_print_object+0x42/0x50 [<8120ec2a>] __debug_object_init+0x279/0x2d7 [<8120ecb3>] debug_object_init+0x13/0x18 [<810409d2>] init_timer_key+0x17/0x6f [<81041526>] free_uid+0x50/0x6c [<8104ed2d>] put_cred_rcu+0x61/0x72 [<81067fac>] rcu_do_batch+0x70/0x121 debugobjects warns about an enqueued timer being initialized. If CONFIG_USER_SCHED=y the user management code uses delayed work to remove the user from the hash table and tear down the sysfs objects. free_uid is called from RCU and initializes/schedules delayed work if the usage count of the user_struct is 0. The init/schedule happens outside of the uidhash_lock protected region which allows a concurrent caller of find_user() to reference the about to be destroyed user_struct w/o preventing the work from being scheduled. If the next free_uid call happens before the work timer expired then the active timer is initialized and the work scheduled again. The race was introduced in commit 5cb350ba (sched: group scheduling, sysfs tunables) and made more prominent by commit 3959214f (sched: delayed cleanup of user_struct) Move the init/schedule_delayed_work inside of the uidhash_lock protected region to prevent the race. Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Acked-by: Dhaval Giani <dhaval@linux.vnet.ibm.com> Cc: Paul E. McKenney <paulmck@us.ibm.com> Cc: Kay Sievers <kay.sievers@vrfy.org> Cc: stable@kernel.org
* | Merge branch 'irq-fixes-for-linus' of ↵Linus Torvalds2009-11-11
|\ \ | | | | | | | | | | | | | | | | | | git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip * 'irq-fixes-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip: genirq: try_one_irq() must be called with irq disabled
| * | genirq: try_one_irq() must be called with irq disabledYong Zhang2009-11-07
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Prarit reported: ================================= [ INFO: inconsistent lock state ] 2.6.32-rc5 #1 --------------------------------- inconsistent {IN-HARDIRQ-W} -> {HARDIRQ-ON-W} usage. swapper/0 [HC0[0]:SC1[1]:HE1:SE0] takes: (&irq_desc_lock_class){?.-...}, at: [<ffffffff810c264e>] try_one_irq+0x32/0x138 {IN-HARDIRQ-W} state was registered at: [<ffffffff81095160>] __lock_acquire+0x2fc/0xd5d [<ffffffff81095cb4>] lock_acquire+0xf3/0x12d [<ffffffff814cdadd>] _spin_lock+0x40/0x89 [<ffffffff810c3389>] handle_level_irq+0x30/0x105 [<ffffffff81014e0e>] handle_irq+0x95/0xb7 [<ffffffff810141bd>] do_IRQ+0x6a/0xe0 [<ffffffff81012813>] ret_from_intr+0x0/0x16 irq event stamp: 195096 hardirqs last enabled at (195096): [<ffffffff814cd7f7>] _spin_unlock_irq+0x3a/0x5c hardirqs last disabled at (195095): [<ffffffff814cdbdd>] _spin_lock_irq+0x29/0x95 softirqs last enabled at (195088): [<ffffffff81068c92>] __do_softirq+0x1c1/0x1ef softirqs last disabled at (195093): [<ffffffff8101304c>] call_softirq+0x1c/0x30 other info that might help us debug this: 1 lock held by swapper/0: #0: (kernel/irq/spurious.c:21){+.-...}, at: [<ffffffff81070cf2>] run_timer_softirq+0x1a9/0x315 stack backtrace: Pid: 0, comm: swapper Not tainted 2.6.32-rc5 #1 Call Trace: <IRQ> [<ffffffff81093e94>] valid_state+0x187/0x1ae [<ffffffff81093fe4>] mark_lock+0x129/0x253 [<ffffffff810951d4>] __lock_acquire+0x370/0xd5d [<ffffffff81095cb4>] lock_acquire+0xf3/0x12d [<ffffffff814cdadd>] _spin_lock+0x40/0x89 [<ffffffff810c264e>] try_one_irq+0x32/0x138 [<ffffffff810c2795>] poll_all_shared_irqs+0x41/0x6d [<ffffffff810c27dd>] poll_spurious_irqs+0x1c/0x49 [<ffffffff81070d82>] run_timer_softirq+0x239/0x315 [<ffffffff81068bd3>] __do_softirq+0x102/0x1ef [<ffffffff8101304c>] call_softirq+0x1c/0x30 [<ffffffff81014b65>] do_softirq+0x59/0xca [<ffffffff810686ad>] irq_exit+0x58/0xae [<ffffffff81029b84>] smp_apic_timer_interrupt+0x94/0xba [<ffffffff81012a33>] apic_timer_interrupt+0x13/0x20 The reason is that try_one_irq() is called from hardirq context with interrupts disabled and from softirq context (poll_all_shared_irqs()) with interrupts enabled. Disable interrupts before calling it from poll_all_shared_irqs(). Reported-and-tested-by: Prarit Bhargava <prarit@redhat.com> Signed-off-by: Yong Zhang <yong.zhang0@gmail.com> LKML-Reference: <1257563773-4620-1-git-send-email-yong.zhang0@gmail.com> Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
* | | sched: Use root_task_group_empty only with FAIR_GROUP_SCHEDCyrill Gorcunov2009-11-08
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | root_task_group_empty is used only with FAIR_GROUP_SCHED so if we use other scheduler options we get: kernel/sched.c:314: warning: 'root_task_group_empty' defined but not used So move CONFIG_FAIR_GROUP_SCHED up that it covers root_task_group_empty(). Signed-off-by: Cyrill Gorcunov <gorcunov@openvz.org> Cc: Peter Zijlstra <peterz@infradead.org> LKML-Reference: <20091026192414.GB5321@lenovo> Signed-off-by: Ingo Molnar <mingo@elte.hu>
* | | sched: Fix kernel-doc function parameter nameRandy Dunlap2009-11-08
|/ / | | | | | | | | | | | | | | | | | | | | | | | | | | Fix variable name in sched.c kernel-doc notation. Fixes this DocBook warning: Warning(kernel/sched.c:2008): No description found for parameter 'p' Warning(kernel/sched.c:2008): Excess function parameter 'k' description in 'kthread_bind' Signed-off-by: Randy Dunlap <randy.dunlap@oracle.com> LKML-Reference: <4AF4B1BC.8020604@oracle.com> Signed-off-by: Ingo Molnar <mingo@elte.hu>
* | Merge branch 'sched-fixes-for-linus' of ↵Linus Torvalds2009-11-05
|\ \ | | | | | | | | | | | | | | | | | | | | | | | | | | | git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip * 'sched-fixes-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip: sched: Fix kthread_bind() by moving the body of kthread_bind() to sched.c sched: Disable SD_PREFER_LOCAL at node level sched: Fix boot crash by zalloc()ing most of the cpu masks sched: Strengthen buddies and mitigate buddy induced latencies
| * | sched: Fix kthread_bind() by moving the body of kthread_bind() to sched.cMike Galbraith2009-11-03
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Eric Paris reported that commit f685ceacab07d3f6c236f04803e2f2f0dbcc5afb causes boot time PREEMPT_DEBUG complaints. [ 4.590699] BUG: using smp_processor_id() in preemptible [00000000] code: rmmod/1314 [ 4.593043] caller is task_hot+0x86/0xd0 Since kthread_bind() messes with scheduler internals, move the body to sched.c, and lock the runqueue. Reported-by: Eric Paris <eparis@redhat.com> Signed-off-by: Mike Galbraith <efault@gmx.de> Tested-by: Eric Paris <eparis@redhat.com> Cc: Peter Zijlstra <a.p.zijlstra@chello.nl> LKML-Reference: <1256813310.7574.3.camel@marge.simson.net> [ v2: fix !SMP build and clean up ] Signed-off-by: Ingo Molnar <mingo@elte.hu>
| * | sched: Fix boot crash by zalloc()ing most of the cpu masksRusty Russell2009-11-02
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | I got a boot crash when forcing cpumasks offstack on 32 bit, because find_new_ilb() returned 3 on my UP system (nohz.cpu_mask wasn't zeroed). AFAICT the others need to be zeroed too: only nohz.ilb_grp_nohz_mask is initialized before use. Signed-off-by: Rusty Russell <rusty@rustcorp.com.au> Cc: Peter Zijlstra <peterz@infradead.org> LKML-Reference: <200911022037.21282.rusty@rustcorp.com.au> Signed-off-by: Ingo Molnar <mingo@elte.hu>
| * | sched: Strengthen buddies and mitigate buddy induced latenciesMike Galbraith2009-10-23
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | This patch restores the effectiveness of LAST_BUDDY in preventing pgsql+oltp from collapsing due to wakeup preemption. It also switches LAST_BUDDY to exclusively do what it does best, namely mitigate the effects of aggressive wakeup preemption, which improves vmark throughput markedly, and restores mysql+oltp scalability. Since buddies are about scalability, enable them beginning at the point where we begin expanding sched_latency, namely sched_nr_latency. Previously, buddies were cleared aggressively, which seriously reduced their effectiveness. Not clearing aggressively however, produces a small drop in mysql+oltp throughput immediately after peak, indicating that LAST_BUDDY is actually doing some harm. This is right at the point where X on the desktop in competition with another load wants low latency service. Ergo, do not enable until we need to scale. To mitigate latency induced by buddies, or by a task just missing wakeup preemption, check latency at tick time. Last hunk prevents buddies from stymieing BALANCE_NEWIDLE via CACHE_HOT_BUDDY. Supporting performance tests: tip = v2.6.32-rc5-1497-ga525b32 tipx = NO_GENTLE_FAIR_SLEEPERS NEXT_BUDDY granularity knobs = 31 knobs + 31 buddies tip+x = NO_GENTLE_FAIR_SLEEPERS granularity knobs = 31 knobs (Three run averages except where noted.) vmark: ------ tip 108466 messages per second tip+ 125307 messages per second tip+x 125335 messages per second tipx 117781 messages per second 2.6.31.3 122729 messages per second mysql+oltp: ----------- clients 1 2 4 8 16 32 64 128 256 .......................................................................................... tip 9949.89 18690.20 34801.24 34460.04 32682.88 30765.97 28305.27 25059.64 19548.08 tip+ 10013.90 18526.84 34900.38 34420.14 33069.83 32083.40 30578.30 28010.71 25605.47 tipx 9698.71 18002.70 34477.56 33420.01 32634.30 31657.27 29932.67 26827.52 21487.18 2.6.31.3 8243.11 18784.20 34404.83 33148.38 31900.32 31161.90 29663.81 25995.94 18058.86 pgsql+oltp: ----------- clients 1 2 4 8 16 32 64 128 256 .......................................................................................... tip 13686.37 26609.25 51934.28 51347.81 49479.51 45312.65 36691.91 26851.57 24145.35 tip+ (1x) 13907.85 27135.87 52951.98 52514.04 51742.52 50705.43 49947.97 48374.19 46227.94 tip+x 13906.78 27065.81 52951.19 52542.59 52176.11 51815.94 50838.90 49439.46 46891.00 tipx 13742.46 26769.81 52351.99 51891.73 51320.79 50938.98 50248.65 48908.70 46553.84 2.6.31.3 13815.35 26906.46 52683.34 52061.31 51937.10 51376.80 50474.28 49394.47 47003.25 Signed-off-by: Mike Galbraith <efault@gmx.de> Cc: Peter Zijlstra <a.p.zijlstra@chello.nl> LKML-Reference: <new-submission> Signed-off-by: Ingo Molnar <mingo@elte.hu>
* | | Merge branch 'tracing-fixes-for-linus' of ↵Linus Torvalds2009-11-05
|\ \ \ | | | | | | | | | | | | | | | | | | | | | | | | | | | | git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip * 'tracing-fixes-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip: ftrace: Fix unmatched locking in ftrace_regex_write() ring-buffer: Synchronize resizing buffer with reader lock
| * | | ftrace: Fix unmatched locking in ftrace_regex_write()Li Zefan2009-11-04
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | When a command is passed to the set_ftrace_filter, then the ftrace_regex_lock is still held going back to user space. # echo 'do_open : foo' > set_ftrace_filter (still holding ftrace_regex_lock when returning to user space!) Signed-off-by: Li Zefan <lizf@cn.fujitsu.com> LKML-Reference: <4AEF7F8A.3080300@cn.fujitsu.com> Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
| * | | ring-buffer: Synchronize resizing buffer with reader lockLai Jiangshan2009-11-04
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | We got a sudden panic when we reduced the size of the ringbuffer. We can reproduce the panic by the following steps: echo 1 > events/sched/enable cat trace_pipe > /dev/null & while ((1)) do echo 12000 > buffer_size_kb echo 512 > buffer_size_kb done (not more than 5 seconds, panic ...) Reported-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> Signed-off-by: Lai Jiangshan <laijs@cn.fujitsu.com> LKML-Reference: <4AF01735.9060409@cn.fujitsu.com> Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
* | | | Merge branch 'pm-fixes' of ↵Linus Torvalds2009-11-03
|\ \ \ \ | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | 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: Remove some debug messages producing too much noise PM: Fix warning on suspend errors PM / Hibernate: Add newline to load_image() fail path PM / Hibernate: Fix error handling in save_image() PM / Hibernate: Fix blkdev refleaks PM / yenta: Split resume into early and late parts (rev. 4)
| * | | | PM / Hibernate: Add newline to load_image() fail pathJiri Slaby2009-11-03
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Finish a line by \n when load_image fails in the middle of loading. Signed-off-by: Jiri Slaby <jirislaby@gmail.com> Acked-by: Pavel Machek <pavel@ucw.cz> Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl>
| * | | | PM / Hibernate: Fix error handling in save_image()Jiri Slaby2009-11-03
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | There are too many retval variables in save_image(). Thus error return value from snapshot_read_next() may be ignored and only part of the snapshot (successfully) written. Remove 'error' variable, invert the condition in the do-while loop and convert the loop to use only 'ret' variable. Switch the rest of the function to consider only 'ret'. Also make sure we end printed line by \n if an error occurs. Signed-off-by: Jiri Slaby <jirislaby@gmail.com> Acked-by: Pavel Machek <pavel@ucw.cz> Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl>
| * | | | PM / Hibernate: Fix blkdev refleaksJiri Slaby2009-11-03
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | While cruising through the swsusp code I found few blkdev reference leaks of resume_bdev. swsusp_read: remove blkdev_put altogether. Some fail paths do not do that. swsusp_check: make sure we always put a reference on fail paths software_resume: all fail paths between swsusp_check and swsusp_read omit swsusp_close. Add it in those cases. And since swsusp_read doesn't drop the reference anymore, do it here unconditionally. [rjw: Fixed a small coding style issue.] Signed-off-by: Jiri Slaby <jirislaby@gmail.com> Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl>
* | | | | Correct nr_processes() when CPUs have been unpluggedIan Campbell2009-11-03
|/ / / / | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | nr_processes() returns the sum of the per cpu counter process_counts for all online CPUs. This counter is incremented for the current CPU on fork() and decremented for the current CPU on exit(). Since a process does not necessarily fork and exit on the same CPU the process_count for an individual CPU can be either positive or negative and effectively has no meaning in isolation. Therefore calculating the sum of process_counts over only the online CPUs omits the processes which were started or stopped on any CPU which has since been unplugged. Only the sum of process_counts across all possible CPUs has meaning. The only caller of nr_processes() is proc_root_getattr() which calculates the number of links to /proc as stat->nlink = proc_root.nlink + nr_processes(); You don't have to be all that unlucky for the nr_processes() to return a negative value leading to a negative number of links (or rather, an apparently enormous number of links). If this happens then you can get failures where things like "ls /proc" start to fail because they got an -EOVERFLOW from some stat() call. Example with some debugging inserted to show what goes on: # ps haux|wc -l nr_processes: CPU0: 90 nr_processes: CPU1: 1030 nr_processes: CPU2: -900 nr_processes: CPU3: -136 nr_processes: TOTAL: 84 proc_root_getattr. nlink 12 + nr_processes() 84 = 96 84 # echo 0 >/sys/devices/system/cpu/cpu1/online # ps haux|wc -l nr_processes: CPU0: 85 nr_processes: CPU2: -901 nr_processes: CPU3: -137 nr_processes: TOTAL: -953 proc_root_getattr. nlink 12 + nr_processes() -953 = -941 75 # stat /proc/ nr_processes: CPU0: 84 nr_processes: CPU2: -901 nr_processes: CPU3: -137 nr_processes: TOTAL: -954 proc_root_getattr. nlink 12 + nr_processes() -954 = -942 File: `/proc/' Size: 0 Blocks: 0 IO Block: 1024 directory Device: 3h/3d Inode: 1 Links: 4294966354 Access: (0555/dr-xr-xr-x) Uid: ( 0/ root) Gid: ( 0/ root) Access: 2009-11-03 09:06:55.000000000 +0000 Modify: 2009-11-03 09:06:55.000000000 +0000 Change: 2009-11-03 09:06:55.000000000 +0000 I'm not 100% convinced that the per_cpu regions remain valid for offline CPUs, although my testing suggests that they do. If not then I think the correct solution would be to aggregate the process_count for a given CPU into a global base value in cpu_down(). This bug appears to pre-date the transition to git and it looks like it may even have been present in linux-2.6.0-test7-bk3 since it looks like the code Rusty patched in http://lwn.net/Articles/64773/ was already wrong. Signed-off-by: Ian Campbell <ian.campbell@citrix.com> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: Rusty Russell <rusty@rustcorp.com.au> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* | | | Merge branch 'core-fixes-for-linus' of ↵Linus Torvalds2009-11-02
|\ \ \ \ | | |_|/ | |/| | | | | | | | | | | | | | | | | | git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip * 'core-fixes-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip: futex: Fix spurious wakeup for requeue_pi really
| * | | futex: Fix spurious wakeup for requeue_pi reallyThomas Gleixner2009-10-28
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | The requeue_pi path doesn't use unqueue_me() (and the racy lock_ptr == NULL test) nor does it use the wake_list of futex_wake() which where the reason for commit 41890f2 (futex: Handle spurious wake up) See debugging discussing on LKML Message-ID: <4AD4080C.20703@us.ibm.com> The changes in this fix to the wait_requeue_pi path were considered to be a likely unecessary, but harmless safety net. But it turns out that due to the fact that for unknown $@#!*( reasons EWOULDBLOCK is defined as EAGAIN we built an endless loop in the code path which returns correctly EWOULDBLOCK. Spurious wakeups in wait_requeue_pi code path are unlikely so we do the easy solution and return EWOULDBLOCK^WEAGAIN to user space and let it deal with the spurious wakeup. Cc: Darren Hart <dvhltc@us.ibm.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Eric Dumazet <eric.dumazet@gmail.com> Cc: John Stultz <johnstul@linux.vnet.ibm.com> Cc: Dinakar Guniguntala <dino@in.ibm.com> LKML-Reference: <4AE23C74.1090502@us.ibm.com> Cc: stable@kernel.org Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
* | | | Merge branch 'perf-fixes-for-linus' of ↵Linus Torvalds2009-11-02
|\ \ \ \ | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip * 'perf-fixes-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip: perf tools: Remove -Wcast-align perf tools: Fix compatibility with libelf 0.8 and autodetect perf events: Don't generate events for the idle task when exclude_idle is set perf events: Fix swevent hrtimer sampling by keeping track of remaining time when enabling/disabling swevent hrtimers
| * | | | perf events: Don't generate events for the idle task when exclude_idle is setSoeren Sandmann2009-10-23
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Getting samples for the idle task is often not interesting, so don't generate them when exclude_idle is set for the event in question. Signed-off-by: Søren Sandmann Pedersen <sandmann@redhat.com> Cc: Peter Zijlstra <a.p.zijlstra@chello.nl> Cc: Mike Galbraith <efault@gmx.de> Cc: Paul Mackerras <paulus@samba.org> Cc: Arnaldo Carvalho de Melo <acme@redhat.com> Cc: Frederic Weisbecker <fweisbec@gmail.com> Cc: Steven Rostedt <rostedt@goodmis.org> LKML-Reference: <ye8pr8fmlq7.fsf@camel16.daimi.au.dk> Signed-off-by: Ingo Molnar <mingo@elte.hu>
| * | | | perf events: Fix swevent hrtimer sampling by keeping track of remaining time ↵Soeren Sandmann2009-10-23
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | when enabling/disabling swevent hrtimers Make the hrtimer based events work for sysprof. Whenever a swevent is scheduled out, the hrtimer is canceled. When it is scheduled back in, the timer is restarted. This happens every scheduler tick, which means the timer never expired because it was getting repeatedly restarted over and over with the same period. To fix that, save the remaining time when disabling; when reenabling, use that saved time as the period instead of the user-specified sampling period. Also, move the starting and stopping of the hrtimers to helper functions instead of duplicating the code. Signed-off-by: Søren Sandmann Pedersen <sandmann@redhat.com> LKML-Reference: <ye8vdi7mluz.fsf@camel16.daimi.au.dk> Signed-off-by: Ingo Molnar <mingo@elte.hu>
* | | | | Merge branch 'tracing-fixes-for-linus' of ↵Linus Torvalds2009-11-02
|\ \ \ \ \ | | |_|/ / | |/| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip * 'tracing-fixes-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip: tracing: Remove cpu arg from the rb_time_stamp() function tracing: Fix comment typo and documentation example tracing: Fix trace_seq_printf() return value tracing: Update *ppos instead of filp->f_pos
| * | | | tracing: Remove cpu arg from the rb_time_stamp() functionJiri Olsa2009-10-24
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | The cpu argument is not used inside the rb_time_stamp() function. Plus fix a typo. Signed-off-by: Jiri Olsa <jolsa@redhat.com> Signed-off-by: Steven Rostedt <rostedt@goodmis.org> Cc: Frederic Weisbecker <fweisbec@gmail.com> LKML-Reference: <20091023233647.118547500@goodmis.org> Signed-off-by: Ingo Molnar <mingo@elte.hu>
| * | | | tracing: Fix comment typo and documentation exampleJiri Olsa2009-10-24
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Trivial patch to fix a documentation example and to fix a comment. Signed-off-by: Jiri Olsa <jolsa@redhat.com> Signed-off-by: Steven Rostedt <rostedt@goodmis.org> Cc: Frederic Weisbecker <fweisbec@gmail.com> LKML-Reference: <20091023233646.871719877@goodmis.org> Signed-off-by: Ingo Molnar <mingo@elte.hu>
| * | | | tracing: Fix trace_seq_printf() return valueJiri Olsa2009-10-24
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | trace_seq_printf() return value is a little ambiguous. It currently returns the length of the space available in the buffer. printf usually returns the amount written. This is not adequate here, because: trace_seq_printf(s, ""); is perfectly legal, and returning 0 would indicate that it failed. We can always see the amount written by looking at the before and after values of s->len. This is not quite the same use as printf. We only care if the string was successfully written to the buffer or not. Make trace_seq_printf() return 0 if the trace oversizes the buffer's free space, 1 otherwise. Signed-off-by: Jiri Olsa <jolsa@redhat.com> Signed-off-by: Steven Rostedt <rostedt@goodmis.org> Cc: Frederic Weisbecker <fweisbec@gmail.com> LKML-Reference: <20091023233646.631787612@goodmis.org> Signed-off-by: Ingo Molnar <mingo@elte.hu>
| * | | | tracing: Update *ppos instead of filp->f_posJiri Olsa2009-10-24
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Instead of directly updating filp->f_pos we should update the *ppos argument. The filp->f_pos gets updated within the file_pos_write() function called from sys_write(). Signed-off-by: Jiri Olsa <jolsa@redhat.com> Signed-off-by: Steven Rostedt <rostedt@goodmis.org> Cc: Frederic Weisbecker <fweisbec@gmail.com> LKML-Reference: <20091023233646.399670810@goodmis.org> Signed-off-by: Ingo Molnar <mingo@elte.hu>
* | | | | Merge branch 'for-linus' of ↵Linus Torvalds2009-10-29
|\ \ \ \ \ | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | git://git.kernel.org/pub/scm/linux/kernel/git/tj/percpu * 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/percpu: sched: move rq_weight data array out of .percpu percpu: allow pcpu_alloc() to be called with IRQs off
| * | | | | sched: move rq_weight data array out of .percpuJiri Kosina2009-10-28
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Commit 34d76c41 introduced percpu array update_shares_data, size of which being proportional to NR_CPUS. Unfortunately this blows up ia64 for large NR_CPUS configuration, as ia64 allows only 64k for .percpu section. Fix this by allocating this array dynamically and keep only pointer to it percpu. The per-cpu handling doesn't impose significant performance penalty on potentially contented path in tg_shares_up(). ... ffffffff8104337c: 65 48 8b 14 25 20 cd mov %gs:0xcd20,%rdx ffffffff81043383: 00 00 ffffffff81043385: 48 c7 c0 00 e1 00 00 mov $0xe100,%rax ffffffff8104338c: 48 c7 45 a0 00 00 00 movq $0x0,-0x60(%rbp) ffffffff81043393: 00 ffffffff81043394: 48 c7 45 a8 00 00 00 movq $0x0,-0x58(%rbp) ffffffff8104339b: 00 ffffffff8104339c: 48 01 d0 add %rdx,%rax ffffffff8104339f: 49 8d 94 24 08 01 00 lea 0x108(%r12),%rdx ffffffff810433a6: 00 ffffffff810433a7: b9 ff ff ff ff mov $0xffffffff,%ecx ffffffff810433ac: 48 89 45 b0 mov %rax,-0x50(%rbp) ffffffff810433b0: bb 00 04 00 00 mov $0x400,%ebx ffffffff810433b5: 48 89 55 c0 mov %rdx,-0x40(%rbp) ... After: ... ffffffff8104337c: 65 8b 04 25 28 cd 00 mov %gs:0xcd28,%eax ffffffff81043383: 00 ffffffff81043384: 48 98 cltq ffffffff81043386: 49 8d bc 24 08 01 00 lea 0x108(%r12),%rdi ffffffff8104338d: 00 ffffffff8104338e: 48 8b 15 d3 7f 76 00 mov 0x767fd3(%rip),%rdx # ffffffff817ab368 <update_shares_data> ffffffff81043395: 48 8b 34 c5 00 ee 6d mov -0x7e921200(,%rax,8),%rsi ffffffff8104339c: 81 ffffffff8104339d: 48 c7 45 a0 00 00 00 movq $0x0,-0x60(%rbp) ffffffff810433a4: 00 ffffffff810433a5: b9 ff ff ff ff mov $0xffffffff,%ecx ffffffff810433aa: 48 89 7d c0 mov %rdi,-0x40(%rbp) ffffffff810433ae: 48 c7 45 a8 00 00 00 movq $0x0,-0x58(%rbp) ffffffff810433b5: 00 ffffffff810433b6: bb 00 04 00 00 mov $0x400,%ebx ffffffff810433bb: 48 01 f2 add %rsi,%rdx ffffffff810433be: 48 89 55 b0 mov %rdx,-0x50(%rbp) ... Signed-off-by: Jiri Kosina <jkosina@suse.cz> Acked-by: Ingo Molnar <mingo@elte.hu> Signed-off-by: Tejun Heo <tj@kernel.org>
* | | | | | Merge git://git.kernel.org/pub/scm/linux/kernel/git/rusty/linux-2.6-param-fixesLinus Torvalds2009-10-29
|\ \ \ \ \ \ | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | * git://git.kernel.org/pub/scm/linux/kernel/git/rusty/linux-2.6-param-fixes: param: fix setting arrays of bool param: fix NULL comparison on oom param: fix lots of bugs with writing charp params from sysfs, by leaking mem.
| * | | | | | param: fix setting arrays of boolRusty Russell2009-10-28
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | We create a dummy struct kernel_param on the stack for parsing each array element, but we didn't initialize the flags word. This matters for arrays of type "bool", where the flag indicates if it really is an array of bools or unsigned int (old-style). Reported-by: Takashi Iwai <tiwai@suse.de> Signed-off-by: Rusty Russell <rusty@rustcorp.com.au> Cc: stable@kernel.org
| * | | | | | param: fix NULL comparison on oomRusty Russell2009-10-28
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | kp->arg is always true: it's the contents of that pointer we care about. Reported-by: Takashi Iwai <tiwai@suse.de> Signed-off-by: Rusty Russell <rusty@rustcorp.com.au> Cc: stable@kernel.org
| * | | | | | param: fix lots of bugs with writing charp params from sysfs, by leaking mem.Rusty Russell2009-10-28
| | |/ / / / | |/| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | e180a6b7759a "param: fix charp parameters set via sysfs" fixed the case where charp parameters written via sysfs were freed, leaving drivers accessing random memory. Unfortunately, storing a flag in the kparam struct was a bad idea: it's rodata so setting it causes an oops on some archs. But that's not all: 1) module_param_array() on charp doesn't work reliably, since we use an uninitialized temporary struct kernel_param. 2) there's a fundamental race if a module uses this parameter and then it's changed: they will still access the old, freed, memory. The simplest fix (ie. for 2.6.32) is to never free the memory. This prevents all these problems, at cost of a memory leak. In practice, there are only 18 places where a charp is writable via sysfs, and all are root-only writable. Reported-by: Takashi Iwai <tiwai@suse.de> Cc: Sitsofe Wheeler <sitsofe@yahoo.com> Cc: Frederic Weisbecker <fweisbec@gmail.com> Cc: Christof Schmitt <christof.schmitt@de.ibm.com> Signed-off-by: Rusty Russell <rusty@rustcorp.com.au> Cc: stable@kernel.org
* | | | | | Merge branch 'hwpoison-2.6.32' of ↵Linus Torvalds2009-10-29
|\ \ \ \ \ \ | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | git://git.kernel.org/pub/scm/linux/kernel/git/ak/linux-mce-2.6 * 'hwpoison-2.6.32' of git://git.kernel.org/pub/scm/linux/kernel/git/ak/linux-mce-2.6: HWPOISON: fix invalid page count in printk output HWPOISON: Allow schedule_on_each_cpu() from keventd HWPOISON: fix/proc/meminfo alignment HWPOISON: fix oops on ksm pages HWPOISON: Fix page count leak in hwpoison late kill in do_swap_page HWPOISON: return early on non-LRU pages HWPOISON: Add brief hwpoison description to Documentation HWPOISON: Clean up PR_MCE_KILL interface
| * | | | | | HWPOISON: Allow schedule_on_each_cpu() from keventdAndi Kleen2009-10-19
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Right now when calling schedule_on_each_cpu() from keventd there is a deadlock because it tries to schedule a work item on the current CPU too. This happens via lru_add_drain_all() in hwpoison. Just call the function for the current CPU in this case. This is actually faster too. Debugging with Fengguang Wu & Max Asbock Signed-off-by: Andi Kleen <ak@linux.intel.com>
| * | | | | | HWPOISON: Clean up PR_MCE_KILL interfaceAndi Kleen2009-10-03
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | While writing the manpage I noticed some shortcomings in the current interface. - Define symbolic names for all the different values - Boundary check the kill mode values - For symmetry add a get interface too. This allows library code to get/set the current state. - For consistency define a PR_MCE_KILL_DEFAULT value Signed-off-by: Andi Kleen <ak@linux.intel.com>
* | | | | | | Merge branch 'core-fixes-for-linus' of ↵Linus Torvalds2009-10-29
|\ \ \ \ \ \ \ | | |_|_|_|/ / | |/| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip * 'core-fixes-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip: futex: Move drop_futex_key_refs out of spinlock'ed region rcu: Fix TREE_PREEMPT_RCU CPU_HOTPLUG bad-luck hang rcu: Stopgap fix for synchronize_rcu_expedited() for TREE_PREEMPT_RCU rcu: Prevent RCU IPI storms in presence of high call_rcu() load futex: Check for NULL keys in match_futex futex: Handle spurious wake up
| * | | | | | futex: Move drop_futex_key_refs out of spinlock'ed regionDarren Hart2009-10-16
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | When requeuing tasks from one futex to another, the reference held by the requeued task to the original futex location needs to be dropped eventually. Dropping the reference may ultimately lead to a call to "iput_final" and subsequently call into filesystem- specific code - which may be non-atomic. It is therefore safer to defer this drop operation until after the futex_hash_bucket spinlock has been dropped. Originally-From: Helge Bahmann <hcb@chaoticmind.net> Signed-off-by: Darren Hart <dvhltc@us.ibm.com> Cc: <stable@kernel.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Eric Dumazet <eric.dumazet@gmail.com> Cc: Dinakar Guniguntala <dino@in.ibm.com> Cc: John Stultz <johnstul@linux.vnet.ibm.com> Cc: Sven-Thorsten Dietrich <sdietrich@novell.com> Cc: John Kacur <jkacur@redhat.com> LKML-Reference: <4AD7A298.5040802@us.ibm.com> Signed-off-by: Ingo Molnar <mingo@elte.hu>
| * | | | | | rcu: Fix TREE_PREEMPT_RCU CPU_HOTPLUG bad-luck hangPaul E. McKenney2009-10-15
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | If the following sequence of events occurs, then TREE_PREEMPT_RCU will hang waiting for a grace period to complete, eventually OOMing the system: o A TREE_PREEMPT_RCU build of the kernel is booted on a system with more than 64 physical CPUs present (32 on a 32-bit system). Alternatively, a TREE_PREEMPT_RCU build of the kernel is booted with RCU_FANOUT set to a sufficiently small value that the physical CPUs populate two or more leaf rcu_node structures. o A task is preempted in an RCU read-side critical section while running on a CPU corresponding to a given leaf rcu_node structure. o All CPUs corresponding to this same leaf rcu_node structure record quiescent states for the current grace period. o All of these same CPUs go offline (hence the need for enough physical CPUs to populate more than one leaf rcu_node structure). This causes the preempted task to be moved to the root rcu_node structure. At this point, there is nothing left to cause the quiescent state to be propagated up the rcu_node tree, so the current grace period never completes. The simplest fix, especially after considering the deadlock possibilities, is to detect this situation when the last CPU is offlined, and to set that CPU's ->qsmask bit in its leaf rcu_node structure. This will cause the next invocation of force_quiescent_state() to end the grace period. Without this fix, this hang can be triggered in an hour or so on some machines with rcutorture and random CPU onlining/offlining. With this fix, these same machines pass a full 10 hours of this sort of abuse. Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Cc: laijs@cn.fujitsu.com Cc: dipankar@in.ibm.com Cc: mathieu.desnoyers@polymtl.ca Cc: josh@joshtriplett.org Cc: dvhltc@us.ibm.com Cc: niv@us.ibm.com Cc: peterz@infradead.org Cc: rostedt@goodmis.org Cc: Valdis.Kletnieks@vt.edu Cc: dhowells@redhat.com LKML-Reference: <20091015162614.GA19131@linux.vnet.ibm.com> Signed-off-by: Ingo Molnar <mingo@elte.hu>
| * | | | | | rcu: Stopgap fix for synchronize_rcu_expedited() for TREE_PREEMPT_RCUPaul E. McKenney2009-10-15
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | For the short term, map synchronize_rcu_expedited() to synchronize_rcu() for TREE_PREEMPT_RCU and to synchronize_sched_expedited() for TREE_RCU. Longer term, there needs to be a real expedited grace period for TREE_PREEMPT_RCU, but candidate patches to date are considerably more complex and intrusive. Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Cc: laijs@cn.fujitsu.com Cc: dipankar@in.ibm.com Cc: mathieu.desnoyers@polymtl.ca Cc: josh@joshtriplett.org Cc: dvhltc@us.ibm.com Cc: niv@us.ibm.com Cc: peterz@infradead.org Cc: rostedt@goodmis.org Cc: Valdis.Kletnieks@vt.edu Cc: dhowells@redhat.com Cc: npiggin@suse.de Cc: jens.axboe@oracle.com LKML-Reference: <12555405592331-git-send-email-> Signed-off-by: Ingo Molnar <mingo@elte.hu>
| * | | | | | rcu: Prevent RCU IPI storms in presence of high call_rcu() loadPaul E. McKenney2009-10-15
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | As the number of callbacks on a given CPU rises, invoke force_quiescent_state() only every blimit number of callbacks (defaults to 10,000), and even then only if no other CPU has invoked force_quiescent_state() in the meantime. This should fix the performance regression reported by Nick. Reported-by: Nick Piggin <npiggin@suse.de> Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Cc: laijs@cn.fujitsu.com Cc: dipankar@in.ibm.com Cc: mathieu.desnoyers@polymtl.ca Cc: josh@joshtriplett.org Cc: dvhltc@us.ibm.com Cc: niv@us.ibm.com Cc: peterz@infradead.org Cc: rostedt@goodmis.org Cc: Valdis.Kletnieks@vt.edu Cc: dhowells@redhat.com Cc: jens.axboe@oracle.com LKML-Reference: <12555405592133-git-send-email-> Signed-off-by: Ingo Molnar <mingo@elte.hu>
| * | | | | | futex: Check for NULL keys in match_futexDarren Hart2009-10-14
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | If userspace tries to perform a requeue_pi on a non-requeue_pi waiter, it will find the futex_q->requeue_pi_key to be NULL and OOPS. Check for NULL in match_futex() instead of doing explicit NULL pointer checks on all call sites. While match_futex(NULL, NULL) returning false is a little odd, it's still correct as we expect valid key references. Signed-off-by: Darren Hart <dvhltc@us.ibm.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Ingo Molnar <mingo@elte.hu> CC: Eric Dumazet <eric.dumazet@gmail.com> CC: Dinakar Guniguntala <dino@in.ibm.com> CC: John Stultz <johnstul@us.ibm.com> Cc: stable@kernel.org LKML-Reference: <4AD60687.10306@us.ibm.com> Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
| * | | | | | futex: Handle spurious wake upThomas Gleixner2009-10-13
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | The futex code does not handle spurious wake up in futex_wait and futex_wait_requeue_pi. The code assumes that any wake up which was not caused by futex_wake / requeue or by a timeout was caused by a signal wake up and returns one of the syscall restart error codes. In case of a spurious wake up the signal delivery code which deals with the restart error codes is not invoked and we return that error code to user space. That causes applications which actually check the return codes to fail. Blaise reported that on preempt-rt a python test program run into a exception trap. -rt exposed that due to a built in spurious wake up accelerator :) Solve this by checking signal_pending(current) in the wake up path and handle the spurious wake up case w/o returning to user space. Reported-by: Blaise Gassend <blaise@willowgarage.com> Debugged-by: Darren Hart <dvhltc@us.ibm.com> Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Cc: Peter Zijlstra <peterz@infradead.org> Cc: stable@kernel.org LKML-Reference: <new-submission>
* | | | | | | Merge branch 'perf-fixes-for-linus' of ↵Linus Torvalds2009-10-29
|\ \ \ \ \ \ \ | | |_|_|_|/ / | |/| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip * 'perf-fixes-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip: perf timechart: Improve the visual appearance of scheduler delays perf timechart: Fix the wakeup-arrows that point to non-visible processes perf top: Fix --delay_secs 0 division by zero perf tools: Bump version to 0.0.2 perf_event: Adjust frequency and unthrottle for non-group-leader events
| * | | | | | perf_event: Adjust frequency and unthrottle for non-group-leader eventsPaul Mackerras2009-10-14
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | The loop in perf_ctx_adjust_freq checks the frequency of sampling event counters, and adjusts the event interval and unthrottles the event if required, and resets the interrupt count for the event. However, at present it only looks at group leaders. This means that a sampling event that is not a group leader will eventually get throttled, once its interrupt count reaches sysctl_perf_event_sample_rate/HZ --- and that is guaranteed to happen, if the event is active for long enough, since the interrupt count never gets reset. Once it is throttled it never gets unthrottled, so it basically just stops working at that point. This fixes it by making perf_ctx_adjust_freq use ctx->event_list rather than ctx->group_list. The existing spin_lock/spin_unlock around the loop makes it unnecessary to put rcu_read_lock/ rcu_read_unlock around the list_for_each_entry_rcu(). Reported-by: Mark W. Krentel <krentel@cs.rice.edu> Signed-off-by: Paul Mackerras <paulus@samba.org> Cc: Corey Ashford <cjashfor@linux.vnet.ibm.com> Cc: Peter Zijlstra <a.p.zijlstra@chello.nl> LKML-Reference: <19157.26731.855609.165622@cargo.ozlabs.ibm.com> Signed-off-by: Ingo Molnar <mingo@elte.hu>
* | | | | | | Merge branch 'sched-fixes-for-linus' of ↵Linus Torvalds2009-10-29
|\ \ \ \ \ \ \ | | |_|_|_|_|/ | |/| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip * 'sched-fixes-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip: sched: Do less agressive buddy clearing sched: Disable SD_PREFER_LOCAL for MC/CPU domains
| * | | | | | sched: Do less agressive buddy clearingPeter Zijlstra2009-10-14
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Yanmin reported a hackbench regression due to: > commit de69a80be32445b0a71e8e3b757e584d7beb90f7 > Author: Peter Zijlstra <a.p.zijlstra@chello.nl> > Date: Thu Sep 17 09:01:20 2009 +0200 > > sched: Stop buddies from hogging the system I really liked de69a80b, and it affecting hackbench shows I wasn't crazy ;-) So hackbench is a multi-cast, with one sender spraying multiple receivers, who in their turn don't spray back. This would be exactly the scenario that patch 'cures'. Previously we would not clear the last buddy after running the next task, allowing the sender to get back to work sooner than it otherwise ought to have been, increasing latencies for other tasks. Now, since those receivers don't poke back, they don't enforce the buddy relation, which means there's nothing to re-elect the sender. Cure this by less agressively clearing the buddy stats. Only clear buddies when they were not chosen. It should still avoid a buddy sticking around long after its served its time. Reported-by: "Zhang, Yanmin" <yanmin_zhang@linux.intel.com> Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl> CC: Mike Galbraith <efault@gmx.de> LKML-Reference: <1255084986.8802.46.camel@laptop> Signed-off-by: Ingo Molnar <mingo@elte.hu>
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