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Commit ac44d354 authored by Balbir Singh's avatar Balbir Singh Committed by Linus Torvalds
Browse files

Memory controller use rcu_read_lock() in mem_cgroup_cache_charge() 



Hugh Dickins noticed that we were using rcu_dereference() without
rcu_read_lock() in the cache charging routine. The patch below fixes
this problem

Signed-off-by: default avatarBalbir Singh <balbir@linux.vnet.ibm.com>
Acked-by: default avatarKAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Cc: Hugh Dickins <hugh@veritas.com>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent 217bc319

mm/memcontrol.c

+7 −3
Original line number Diff line number Diff line
@@ -456,16 +456,20 @@ int mem_cgroup_charge(struct page *page, struct mm_struct *mm, 
int mem_cgroup_cache_charge(struct page *page, struct mm_struct *mm,

				gfp_t gfp_mask)

{

	int ret = 0;

	struct mem_cgroup *mem;

	if (!mm)

		mm = &init_mm;



	rcu_read_lock();

	mem = rcu_dereference(mm->mem_cgroup);

	css_get(&mem->css);

	rcu_read_unlock();

	if (mem->control_type == MEM_CGROUP_TYPE_ALL)

		return mem_cgroup_charge_common(page, mm, gfp_mask,

		ret = mem_cgroup_charge_common(page, mm, gfp_mask,

				MEM_CGROUP_CHARGE_TYPE_CACHE);

	else

		return 0;

	css_put(&mem->css);

	return ret;

}



/*