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 e8abccb7193 ("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
events
gcov
irq	irq: Fix check for already initialized irq_domain in irq_domain_add	2011-09-20 12:16:22 +02:00
power
time
trace
.gitignore
acct.c
async.c
audit_tree.c
audit_watch.c
audit.c
audit.h
auditfilter.c
auditsc.c
backtracetest.c
bounds.c
capability.c
cgroup_freezer.c
cgroup.c
compat.c
configs.c
cpu.c
cpuset.c
crash_dump.c
cred.c
delayacct.c
dma.c
elfcore.c
exec_domain.c
exit.c
extable.c
fork.c
freezer.c
futex_compat.c
futex.c
groups.c
hrtimer.c
hung_task.c
irq_work.c
itimer.c
jump_label.c
kallsyms.c
Kconfig.freezer
Kconfig.hz
Kconfig.locks
Kconfig.preempt
kexec.c
kfifo.c
kmod.c
kprobes.c
ksysfs.c
kthread.c
latencytop.c
lockdep_internals.h
lockdep_proc.c
lockdep_states.h
lockdep.c
Makefile
module.c
mutex-debug.c
mutex-debug.h
mutex.c
mutex.h
notifier.c
nsproxy.c
padata.c
panic.c
params.c
pid_namespace.c
pid.c
pm_qos_params.c
posix-cpu-timers.c	cputimer: Cure lock inversion	2011-10-18 11:36:59 +02:00
posix-timers.c
printk.c
profile.c
ptrace.c	ptrace: PTRACE_LISTEN forgets to unlock ->siglock	2011-09-25 11:02:00 -07:00
range.c
rcupdate.c
rcutiny_plugin.h
rcutiny.c
rcutorture.c
rcutree_plugin.h
rcutree_trace.c
rcutree.c
rcutree.h
relay.c
res_counter.c
resource.c	Resource: fix wrong resource window calculation	2011-09-29 20:04:34 -07:00
rtmutex_common.h
rtmutex-debug.c
rtmutex-debug.h
rtmutex-tester.c
rtmutex.c
rtmutex.h
rwsem.c
sched_autogroup.c
sched_autogroup.h
sched_clock.c
sched_cpupri.c
sched_cpupri.h
sched_debug.c
sched_fair.c
sched_features.h
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
sched.c	posix-cpu-timers: Cure SMP wobbles	2011-09-30 14:07:06 +02:00
seccomp.c
semaphore.c
signal.c
smp.c
softirq.c
spinlock.c
srcu.c
stacktrace.c
stop_machine.c
sys_ni.c
sys.c	Avoid using variable-length arrays in kernel/sys.c	2011-10-17 08:24:24 -07:00
sysctl_binary.c
sysctl_check.c
sysctl.c
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_namespace.c
user-return-notifier.c
user.c
utsname_sysctl.c
utsname.c
wait.c
watchdog.c
workqueue_sched.h
workqueue.c	workqueue: lock cwq access in drain_workqueue	2011-09-14 18:09:38 -07:00