diff options
| author | Steven Rostedt <[email protected]> | 2011-11-02 13:38:33 -0700 |
|---|---|---|
| committer | Linus Torvalds <[email protected]> | 2011-11-02 16:07:00 -0700 |
| commit | 4799401fef9d5951b2da384c5eb08034c48e08a0 (patch) | |
| tree | 94f9113c6870f46811aaa0f08cdb3ca2beba1e9c | |
| parent | a61ed3cec51cfd4877855c24890ab8d3e2b143e3 (diff) | |
memcg: Fix race condition in memcg_check_events() with this_cpu usage
Various code in memcontrol.c () calls this_cpu_read() on the calculations
to be done from two different percpu variables, or does an open-coded
read-modify-write on a single percpu variable.
Disable preemption throughout these operations so that the writes go to
the correct palces.
[[email protected]: added this_cpu to __this_cpu conversion]
Signed-off-by: Johannes Weiner <[email protected]>
Signed-off-by: Steven Rostedt <[email protected]>
Cc: Greg Thelen <[email protected]>
Cc: KAMEZAWA Hiroyuki <[email protected]>
Cc: Balbir Singh <[email protected]>
Cc: Daisuke Nishimura <[email protected]>
Cc: Thomas Gleixner <[email protected]>
Cc: Peter Zijlstra <[email protected]>
Cc: Christoph Lameter <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>
| -rw-r--r-- | mm/memcontrol.c | 10 |
1 files changed, 6 insertions, 4 deletions
diff --git a/mm/memcontrol.c b/mm/memcontrol.c index 01e0c725de65..7af1d5ee1598 100644 --- a/mm/memcontrol.c +++ b/mm/memcontrol.c @@ -686,8 +686,8 @@ static bool __memcg_event_check(struct mem_cgroup *memcg, int target) { unsigned long val, next; - val = this_cpu_read(memcg->stat->events[MEM_CGROUP_EVENTS_COUNT]); - next = this_cpu_read(memcg->stat->targets[target]); + val = __this_cpu_read(memcg->stat->events[MEM_CGROUP_EVENTS_COUNT]); + next = __this_cpu_read(memcg->stat->targets[target]); /* from time_after() in jiffies.h */ return ((long)next - (long)val < 0); } @@ -696,7 +696,7 @@ static void __mem_cgroup_target_update(struct mem_cgroup *memcg, int target) { unsigned long val, next; - val = this_cpu_read(memcg->stat->events[MEM_CGROUP_EVENTS_COUNT]); + val = __this_cpu_read(memcg->stat->events[MEM_CGROUP_EVENTS_COUNT]); switch (target) { case MEM_CGROUP_TARGET_THRESH: @@ -712,7 +712,7 @@ static void __mem_cgroup_target_update(struct mem_cgroup *memcg, int target) return; } - this_cpu_write(memcg->stat->targets[target], next); + __this_cpu_write(memcg->stat->targets[target], next); } /* @@ -721,6 +721,7 @@ static void __mem_cgroup_target_update(struct mem_cgroup *memcg, int target) */ static void memcg_check_events(struct mem_cgroup *memcg, struct page *page) { + preempt_disable(); /* threshold event is triggered in finer grain than soft limit */ if (unlikely(__memcg_event_check(memcg, MEM_CGROUP_TARGET_THRESH))) { mem_cgroup_threshold(memcg); @@ -740,6 +741,7 @@ static void memcg_check_events(struct mem_cgroup *memcg, struct page *page) } #endif } + preempt_enable(); } static struct mem_cgroup *mem_cgroup_from_cont(struct cgroup *cont) |