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Commit 58fa2a55 authored by Vladimir Davydov's avatar Vladimir Davydov Committed by Linus Torvalds
Browse files

mm: memcontrol: add sanity checks for memcg->id.ref on get/put 

Link: http://lkml.kernel.org/r/1c5ddb1c171dbdfc3262252769d6138a29b35b70.1470219853.git.vdavydov@virtuozzo.com


Signed-off-by: default avatarVladimir Davydov <vdavydov@virtuozzo.com>
Acked-by: default avatarJohannes Weiner <hannes@cmpxchg.org>
Acked-by: default avatarMichal Hocko <mhocko@suse.com>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent 252e5c6e

mm/memcontrol.c

+5 −1
Original line number Diff line number Diff line
@@ -4062,11 +4062,13 @@ static DEFINE_IDR(mem_cgroup_idr); 


static void mem_cgroup_id_get_many(struct mem_cgroup *memcg, unsigned int n)

{

	VM_BUG_ON(atomic_read(&memcg->id.ref) <= 0);

	atomic_add(n, &memcg->id.ref);

}



static void mem_cgroup_id_put_many(struct mem_cgroup *memcg, unsigned int n)

{

	VM_BUG_ON(atomic_read(&memcg->id.ref) < n);

	if (atomic_sub_and_test(n, &memcg->id.ref)) {

		idr_remove(&mem_cgroup_idr, memcg->id.id);

		memcg->id.id = 0;
@@ -4255,8 +4257,10 @@ mem_cgroup_css_alloc(struct cgroup_subsys_state *parent_css) 


static int mem_cgroup_css_online(struct cgroup_subsys_state *css)

{

	struct mem_cgroup *memcg = mem_cgroup_from_css(css);



	/* Online state pins memcg ID, memcg ID pins CSS */

	mem_cgroup_id_get(mem_cgroup_from_css(css));

	atomic_set(&memcg->id.ref, 1);

	css_get(css);

	return 0;

}