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authorSteven Rostedt <srostedt@redhat.com>2011-11-02 13:38:33 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2011-11-02 16:07:00 -0700
commit4799401fef9d5951b2da384c5eb08034c48e08a0 (patch)
tree94f9113c6870f46811aaa0f08cdb3ca2beba1e9c /mm
parenta61ed3cec51cfd4877855c24890ab8d3e2b143e3 (diff)
downloadlinux-stericsson-4799401fef9d5951b2da384c5eb08034c48e08a0.tar.gz
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>
Diffstat (limited to 'mm')
-rw-r--r--mm/memcontrol.c10
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)