The patch titled
Subject: memcg: Fix race condition in memcg_check_events() with this_cpu usage
has been added to the -mm tree. Its filename is
memcg-fix-race-condition-in-memcg_check_events-with-this_cpu-usage.patch
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------------------------------------------------------
From: Steven Rostedt <srostedt@xxxxxxxxxx>
Subject: 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.
[ Added this_cpu to __this_cpu conversion by Johannes ]
Signed-off-by: Johannes Weiner <hannes@xxxxxxxxxxx>
Signed-off-by: Steven Rostedt <rostedt@xxxxxxxxxxx>
Cc: Greg Thelen <gthelen@xxxxxxxxxx>
Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@xxxxxxxxxxxxxx>
Cc: Balbir Singh <balbir@xxxxxxxxxxxxxxxxxx>
Cc: Daisuke Nishimura <nishimura@xxxxxxxxxxxxxxxxx>
Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
Cc: Christoph Lameter <cl@xxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
mm/memcontrol.c | 10 ++++++----
1 file changed, 6 insertions(+), 4 deletions(-)
diff -puN mm/memcontrol.c~memcg-fix-race-condition-in-memcg_check_events-with-this_cpu-usage mm/memcontrol.c
--- a/mm/memcontrol.c~memcg-fix-race-condition-in-memcg_check_events-with-this_cpu-usage
+++ a/mm/memcontrol.c
@@ -687,8 +687,8 @@ static bool __memcg_event_check(struct m
{
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);
}
@@ -697,7 +697,7 @@ static void __mem_cgroup_target_update(s
{
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:
@@ -713,7 +713,7 @@ static void __mem_cgroup_target_update(s
return;
}
- this_cpu_write(memcg->stat->targets[target], next);
+ __this_cpu_write(memcg->stat->targets[target], next);
}
/*
@@ -722,6 +722,7 @@ static void __mem_cgroup_target_update(s
*/
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);
@@ -741,6 +742,7 @@ static void memcg_check_events(struct me
}
#endif
}
+ preempt_enable();
}
static struct mem_cgroup *mem_cgroup_from_cont(struct cgroup *cont)
_
Subject: Subject: memcg: Fix race condition in memcg_check_events() with this_cpu usage
Patches currently in -mm which might be from srostedt@xxxxxxxxxx are
linux-next.patch
memcg-fix-race-condition-in-memcg_check_events-with-this_cpu-usage.patch
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