linux-stable/kernel/sched
Ben Segall f9f9ffc237 sched: Avoid throttle_cfs_rq() racing with period_timer stopping
throttle_cfs_rq() doesn't check to make sure that period_timer is running,
and while update_curr/assign_cfs_runtime does, a concurrently running
period_timer on another cpu could cancel itself between this cpu's
update_curr and throttle_cfs_rq(). If there are no other cfs_rqs running
in the tg to restart the timer, this causes the cfs_rq to be stranded
forever.

Fix this by calling __start_cfs_bandwidth() in throttle if the timer is
inactive.

(Also add some sched_debug lines for cfs_bandwidth.)

Tested: make a run/sleep task in a cgroup, loop switching the cgroup
between 1ms/100ms quota and unlimited, checking for timer_active=0 and
throttled=1 as a failure. With the throttle_cfs_rq() change commented out
this fails, with the full patch it passes.

Signed-off-by: Ben Segall <bsegall@google.com>
Signed-off-by: Peter Zijlstra <peterz@infradead.org>
Cc: pjt@google.com
Link: http://lkml.kernel.org/r/20131016181632.22647.84174.stgit@sword-of-the-dawn.mtv.corp.google.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2013-10-29 12:02:32 +01:00
..
auto_group.c sched/autogroup: Fix race with task_groups list 2013-05-28 09:40:22 +02:00
auto_group.h Revert "sched/autogroup: Fix crash on reboot when autogroup is disabled" 2012-12-11 10:23:45 +01:00
clock.c sched_clock: Prevent 64bit inatomicity on 32bit systems 2013-04-08 11:50:44 +02:00
core.c sched: Fix race on toggling cfs_bandwidth_used 2013-10-29 12:02:19 +01:00
cpuacct.c cgroup: pass around cgroup_subsys_state instead of cgroup in file methods 2013-08-08 20:11:24 -04:00
cpuacct.h sched/cpuacct: Initialize root cpuacct earlier 2013-04-10 13:54:20 +02:00
cpupri.c sched: Fix some kernel-doc warnings 2013-07-18 09:58:21 +02:00
cpupri.h
cputime.c Merge branch 'timers-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2013-09-05 12:36:46 -07:00
debug.c sched: Avoid throttle_cfs_rq() racing with period_timer stopping 2013-10-29 12:02:32 +01:00
fair.c sched: Avoid throttle_cfs_rq() racing with period_timer stopping 2013-10-29 12:02:32 +01:00
features.h sched/numa: Resist moving tasks towards nodes with fewer hinting faults 2013-10-09 12:40:27 +02:00
idle_task.c sched/numa: Introduce migrate_swap() 2013-10-09 12:40:46 +02:00
Makefile sched: Factor out load calculation code from sched/core.c --> sched/proc.c 2013-05-07 13:14:50 +02:00
proc.c sched: Change get_rq_runnable_load() to static and inline 2013-06-27 10:07:44 +02:00
rt.c sched/rt: Fix task_tick_rt() comment 2013-10-26 12:25:21 +02:00
sched.h sched: Fix race on toggling cfs_bandwidth_used 2013-10-29 12:02:19 +01:00
stats.c fix a leak in /proc/schedstats 2013-04-29 15:41:45 -04:00
stats.h sched: Micro-optimize by dropping unnecessary task_rq() calls 2013-09-25 13:51:06 +02:00
stop_task.c sched/numa: Introduce migrate_swap() 2013-10-09 12:40:46 +02:00