Peter Zijlstra bcd5cff721 cputimer: Cure lock inversion ... There's a lock inversion between the cputimer->lock and rq->lock; notably the two callchains involved are: update_rlimit_cpu() sighand->siglock set_process_cpu_timer() cpu_timer_sample_group() thread_group_cputimer() cputimer->lock thread_group_cputime() task_sched_runtime() ->pi_lock rq->lock scheduler_tick() rq->lock task_tick_fair() update_curr() account_group_exec() cputimer->lock Where the first one is enabling a CLOCK_PROCESS_CPUTIME_ID timer, and the second one is keeping up-to-date. This problem was introduced by e8abccb719 ("posix-cpu-timers: Cure SMP accounting oddities"). Cure the problem by removing the cputimer->lock and rq->lock nesting, this leaves concurrent enablers doing duplicate work, but the time wasted should be on the same order otherwise wasted spinning on the lock and the greater-than assignment filter should ensure we preserve monotonicity. Reported-by: Dave Jones <davej@redhat.com> Reported-by: Simon Kirby <sim@hostway.ca> Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Cc: stable@kernel.org Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Martin Schwidefsky <schwidefsky@de.ibm.com> Link: http://lkml.kernel.org/r/1318928713.21167.4.camel@twins Signed-off-by: Thomas Gleixner <tglx@linutronix.de>		2011-10-18 11:36:59 +02:00
..
debug	Merge branch 'for_linus' of git://git.kernel.org/pub/scm/linux/kernel/git/jwessel/linux-2.6-kgdb	2011-08-01 13:39:40 -10:00
events	perf_event: Fix broken calc_timer_values()	2011-08-31 15:56:29 +02:00
gcov	gcov: disable CONSTRUCTORS for UML	2011-07-26 16:49:45 -07:00
irq	irq: Fix check for already initialized irq_domain in irq_domain_add	2011-09-20 12:16:22 +02:00
power	PM / Domains: Fix build for CONFIG_PM_RUNTIME unset	2011-08-14 13:34:31 +02:00
time	alarmtimers: Avoid possible denial of service with high freq periodic timers	2011-08-10 10:26:09 -07:00
trace	Merge branch 'for-linus' of git://git.kernel.dk/linux-block	2011-08-19 10:47:07 -07:00
.gitignore	…
Kconfig.freezer	…
Kconfig.hz	…
Kconfig.locks	…
Kconfig.preempt	…
Makefile	jump label: Reduce the cycle count by changing the link order	2011-08-05 23:57:33 +02:00
acct.c	…
async.c	…
audit.c	atomic: use <linux/atomic.h>	2011-07-26 16:49:47 -07:00
audit.h	…
audit_tree.c	audit_tree,rcu: Convert call_rcu(__put_tree) to kfree_rcu()	2011-07-20 14:10:11 -07:00
audit_watch.c	…
auditfilter.c	…
auditsc.c	atomic: use <linux/atomic.h>	2011-07-26 16:49:47 -07:00
backtracetest.c	…
bounds.c	…
capability.c	…
cgroup.c	Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/jmorris/security-testing-2.6	2011-07-27 19:26:38 -07:00
cgroup_freezer.c	…
compat.c	Merge branch 'v4l_for_linus' of git://git.kernel.org/pub/scm/linux/kernel/git/mchehab/linux-2.6	2011-07-30 00:08:53 -07:00
configs.c	kernel/configs.c: include MODULE_*() when CONFIG_IKCONFIG_PROC=n	2011-07-25 20:57:15 -07:00
cpu.c	…
cpuset.c	atomic: use <linux/atomic.h>	2011-07-26 16:49:47 -07:00
crash_dump.c	…
cred.c	move RLIMIT_NPROC check from set_user() to do_execve_common()	2011-08-11 11:24:42 -07:00
delayacct.c	KVM: Steal time implementation	2011-07-14 12:59:14 +03:00
dma.c	…
elfcore.c	…
exec_domain.c	…
exit.c	ipc: introduce shm_rmid_forced sysctl	2011-07-26 16:49:44 -07:00
extable.c	…
fork.c	move RLIMIT_NPROC check from set_user() to do_execve_common()	2011-08-11 11:24:42 -07:00
freezer.c	…
futex.c	Merge branch 'linus' into core/urgent	2011-08-04 09:09:27 +02:00
futex_compat.c	…
groups.c	…
hrtimer.c	…
hung_task.c	…
irq_work.c	…
itimer.c	…
jump_label.c	…
kallsyms.c	…
kexec.c	…
kfifo.c	…
kmod.c	Boot up with usermodehelper disabled	2011-08-03 22:03:29 -10:00
kprobes.c	kprobes: Return -ENOENT if probe point doesn't exist	2011-07-15 15:11:47 -04:00
ksysfs.c	…
kthread.c	…
latencytop.c	…
lockdep.c	lockdep: Fix wrong assumption in match_held_lock	2011-08-09 11:57:35 +02:00
lockdep_internals.h	…
lockdep_proc.c	…
lockdep_states.h	…
module.c	module: add /sys/module/<name>/uevent files	2011-07-24 22:06:04 +09:30
mutex-debug.c	…
mutex-debug.h	…
mutex.c	…
mutex.h	…
notifier.c	notifiers: sys: move reboot notifiers into reboot.h	2011-07-25 20:57:14 -07:00
nsproxy.c	make sure that nsproxy_cache is initialized early enough	2011-07-20 01:44:07 -04:00
padata.c	…
panic.c	panic: panic=-1 for immediate reboot	2011-07-26 16:49:45 -07:00
params.c	module: add /sys/module/<name>/uevent files	2011-07-24 22:06:04 +09:30
pid.c	rcu: treewide: Do not use rcu_read_lock_held when calling rcu_dereference_check	2011-07-08 22:21:58 +02:00
pid_namespace.c	…
pm_qos_params.c	plist: Remove the need to supply locks to plist heads	2011-07-08 14:02:53 +02:00
posix-cpu-timers.c	cputimer: Cure lock inversion	2011-10-18 11:36:59 +02:00
posix-timers.c	…
printk.c	kernel/printk: do not turn off bootconsole in printk_late_init() if keep_bootcon	2011-08-25 16:25:34 -07:00
profile.c	…
ptrace.c	ptrace: PTRACE_LISTEN forgets to unlock ->siglock	2011-09-25 11:02:00 -07:00
range.c	…
rcupdate.c	atomic: use <linux/atomic.h>	2011-07-26 16:49:47 -07:00
rcutiny.c	…
rcutiny_plugin.h	…
rcutorture.c	atomic: use <linux/atomic.h>	2011-07-26 16:49:47 -07:00
rcutree.c	rcu: Prevent RCU callbacks from executing before scheduler initialized	2011-07-13 08:17:56 -07:00
rcutree.h	…
rcutree_plugin.h	softirq,rcu: Inform RCU of irq_exit() activity	2011-07-20 10:50:12 -07:00
rcutree_trace.c	atomic: use <linux/atomic.h>	2011-07-26 16:49:47 -07:00
relay.c	…
res_counter.c	…
resource.c	Resource: fix wrong resource window calculation	2011-09-29 20:04:34 -07:00
rtmutex-debug.c	…
rtmutex-debug.h	…
rtmutex-tester.c	…
rtmutex.c	plist: Remove the need to supply locks to plist heads	2011-07-08 14:02:53 +02:00
rtmutex.h	…
rtmutex_common.h	…
rwsem.c	atomic: use <linux/atomic.h>	2011-07-26 16:49:47 -07:00
sched.c	posix-cpu-timers: Cure SMP wobbles	2011-09-30 14:07:06 +02:00
sched_autogroup.c	…
sched_autogroup.h	sched: Skip autogroup when looking for all rt sched groups	2011-07-01 10:39:08 +02:00
sched_clock.c	…
sched_cpupri.c	…
sched_cpupri.h	…
sched_debug.c	…
sched_fair.c	sched: Cleanup duplicate local variable in [enqueue|dequeue]_task_fair	2011-07-22 12:47:22 +02:00
sched_features.h	Merge branch 'kvm-updates/3.1' of git://git.kernel.org/pub/scm/virt/kvm/kvm	2011-07-24 09:07:03 -07:00
sched_idletask.c	…
sched_rt.c	sched/rt: Migrate equal priority tasks to available CPUs	2011-09-18 13:48:56 +02:00
sched_stats.h	…
sched_stoptask.c	…
seccomp.c	…
semaphore.c	…
signal.c	signals: sys_ssetmask/sys_rt_sigsuspend should use set_current_blocked()	2011-07-27 12:53:36 -07:00
smp.c	…
softirq.c	softirq,rcu: Inform RCU of irq_exit() activity	2011-07-20 10:50:12 -07:00
spinlock.c	…
srcu.c	…
stacktrace.c	…
stop_machine.c	atomic: use <linux/atomic.h>	2011-07-26 16:49:47 -07:00
sys.c	Avoid using variable-length arrays in kernel/sys.c	2011-10-17 08:24:24 -07:00
sys_ni.c	All Arch: remove linkage for sys_nfsservctl system call	2011-08-26 15:09:58 -07:00
sysctl.c	sysctl,rcu: Convert call_rcu(free_head) to kfree	2011-07-20 14:10:18 -07:00
sysctl_binary.c	xfs: remove subdirectories	2011-08-12 16:21:35 -05:00
sysctl_check.c	xfs: remove subdirectories	2011-08-12 16:21:35 -05:00
taskstats.c	Make TASKSTATS require root access	2011-09-19 17:04:37 -07:00
test_kprobes.c	…
time.c	…
timeconst.pl	…
timer.c	…
tracepoint.c	…
tsacct.c	Make taskstats round statistics down to nearest 1k bytes/events	2011-09-19 17:10:57 -07:00
uid16.c	…
up.c	…
user-return-notifier.c	…
user.c	…
user_namespace.c	…
utsname.c	…
utsname_sysctl.c	…
wait.c	…
watchdog.c	perf, x86: P4 PMU - Introduce event alias feature	2011-07-14 17:25:04 -04:00
workqueue.c	workqueue: lock cwq access in drain_workqueue	2011-09-14 18:09:38 -07:00
workqueue_sched.h	…