memcg: protect prev_priority
Currently, mem_cgroup doesn't have own lock and almost its member doesn't
need. (e.g. mem_cgroup->info is protected by zone lock, mem_cgroup->stat
is per cpu variable)
However, there is one explict exception. mem_cgroup->prev_priorit need
lock, but doesn't protect. Luckly, this is NOT bug because prev_priority
isn't used for current reclaim code.
However, we plan to use prev_priority future again. Therefore, fixing is
better.
In addition, we plan to reuse this lock for another member. Then
"reclaim_param_lock" name is better than "prev_priority_lock".
Acked-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Signed-off-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Cc: Balbir Singh <balbir@in.ibm.com>
Cc: Daisuke Nishimura <nishimura@mxp.nes.nec.co.jp>
Cc: Hugh Dickins <hugh@veritas.com>
Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/mm/memcontrol.c b/mm/memcontrol.c
index af28e12..027c0dd 100644
--- a/mm/memcontrol.c
+++ b/mm/memcontrol.c
@@ -144,6 +144,11 @@
*/
struct mem_cgroup_lru_info info;
+ /*
+ protect against reclaim related member.
+ */
+ spinlock_t reclaim_param_lock;
+
int prev_priority; /* for recording reclaim priority */
/*
@@ -400,18 +405,28 @@
*/
int mem_cgroup_get_reclaim_priority(struct mem_cgroup *mem)
{
- return mem->prev_priority;
+ int prev_priority;
+
+ spin_lock(&mem->reclaim_param_lock);
+ prev_priority = mem->prev_priority;
+ spin_unlock(&mem->reclaim_param_lock);
+
+ return prev_priority;
}
void mem_cgroup_note_reclaim_priority(struct mem_cgroup *mem, int priority)
{
+ spin_lock(&mem->reclaim_param_lock);
if (priority < mem->prev_priority)
mem->prev_priority = priority;
+ spin_unlock(&mem->reclaim_param_lock);
}
void mem_cgroup_record_reclaim_priority(struct mem_cgroup *mem, int priority)
{
+ spin_lock(&mem->reclaim_param_lock);
mem->prev_priority = priority;
+ spin_unlock(&mem->reclaim_param_lock);
}
int mem_cgroup_inactive_anon_is_low(struct mem_cgroup *memcg, struct zone *zone)
@@ -2076,6 +2091,7 @@
}
mem_cgroup_set_inactive_ratio(mem);
mem->last_scanned_child = NULL;
+ spin_lock_init(&mem->reclaim_param_lock);
return &mem->css;
free_out: