diff options
| author | Ben Segall <bsegall@google.com> | 2013-10-16 11:16:12 -0700 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2014-01-15 15:28:54 -0800 |
| commit | 9d80092f8d9e0fc4aa2b6a7c8d2e4a7437899ca5 (patch) | |
| tree | c1147a830101185a34a04fc263f0d48f36b941ba /kernel/sched/fair.c | |
| parent | e23fe36a8cf5faa57d0c45868a3f7679c4f07cb0 (diff) | |
sched: Fix race on toggling cfs_bandwidth_used
commit 1ee14e6c8cddeeb8a490d7b54cd9016e4bb900b4 upstream.
When we transition cfs_bandwidth_used to false, any currently
throttled groups will incorrectly return false from cfs_rq_throttled.
While tg_set_cfs_bandwidth will unthrottle them eventually, currently
running code (including at least dequeue_task_fair and
distribute_cfs_runtime) will cause errors.
Fix this by turning off cfs_bandwidth_used only after unthrottling all
cfs_rqs.
Tested: toggle bandwidth back and forth on a loaded cgroup. Caused
crashes in minutes without the patch, hasn't crashed with it.
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/20131016181611.22647.80365.stgit@sword-of-the-dawn.mtv.corp.google.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Cc: Chris J Arges <chris.j.arges@canonical.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'kernel/sched/fair.c')
| -rw-r--r-- | kernel/sched/fair.c | 16 |
1 files changed, 9 insertions, 7 deletions
diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c index ce60006132b..54e85898c39 100644 --- a/kernel/sched/fair.c +++ b/kernel/sched/fair.c @@ -2029,13 +2029,14 @@ static inline bool cfs_bandwidth_used(void) return static_key_false(&__cfs_bandwidth_used); } -void account_cfs_bandwidth_used(int enabled, int was_enabled) +void cfs_bandwidth_usage_inc(void) { - /* only need to count groups transitioning between enabled/!enabled */ - if (enabled && !was_enabled) - static_key_slow_inc(&__cfs_bandwidth_used); - else if (!enabled && was_enabled) - static_key_slow_dec(&__cfs_bandwidth_used); + static_key_slow_inc(&__cfs_bandwidth_used); +} + +void cfs_bandwidth_usage_dec(void) +{ + static_key_slow_dec(&__cfs_bandwidth_used); } #else /* HAVE_JUMP_LABEL */ static bool cfs_bandwidth_used(void) @@ -2043,7 +2044,8 @@ static bool cfs_bandwidth_used(void) return true; } -void account_cfs_bandwidth_used(int enabled, int was_enabled) {} +void cfs_bandwidth_usage_inc(void) {} +void cfs_bandwidth_usage_dec(void) {} #endif /* HAVE_JUMP_LABEL */ /* |