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memcg: protect prev_priority

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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>
This commit is contained in:
KOSAKI Motohiro 2009-01-07 18:08:23 -08:00 committed by Linus Torvalds
parent e72e2bd674
commit 2733c06ac8
1 changed files with 17 additions and 1 deletions
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18
mm/memcontrol.c
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@ -144,6 +144,11 @@ struct mem_cgroup {
*/
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_calc_mapped_ratio(struct mem_cgroup *mem)
*/
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_create(struct cgroup_subsys *ss, struct cgroup *cont)
}
mem_cgroup_set_inactive_ratio(mem);
mem->last_scanned_child = NULL;
spin_lock_init(&mem->reclaim_param_lock);
return &mem->css;
free_out: