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Commit 2733c06a authored by KOSAKI Motohiro's avatar KOSAKI Motohiro Committed by Linus Torvalds
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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: default avatarKAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Signed-off-by: default avatarKOSAKI 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: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent e72e2bd6

mm/memcontrol.c

+17 −1
Original line number Diff line number Diff line
@@ -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: