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| author | Steven Rostedt <srostedt@redhat.com> | 2011-11-02 20:38:33 (GMT) |
|---|---|---|
| committer | Linus Torvalds <torvalds@linux-foundation.org> | 2011-11-02 23:07:00 (GMT) |
| commit | 4799401fef9d5951b2da384c5eb08034c48e08a0 (patch) | |
| tree | 94f9113c6870f46811aaa0f08cdb3ca2beba1e9c | |
| parent | a61ed3cec51cfd4877855c24890ab8d3e2b143e3 (diff) | |
| download | linux-4799401fef9d5951b2da384c5eb08034c48e08a0.tar.xz | |
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.
[hannes@cmpxchg.org: added this_cpu to __this_cpu conversion]
Signed-off-by: Johannes Weiner <hannes@cmpxchg.org>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
Cc: Greg Thelen <gthelen@google.com>
Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Cc: Balbir Singh <balbir@linux.vnet.ibm.com>
Cc: Daisuke Nishimura <nishimura@mxp.nes.nec.co.jp>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Christoph Lameter <cl@linux.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
| -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 01e0c72..7af1d5e 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) |