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

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Link: http://lkml.kernel.org/r/1c5ddb1c171dbdfc3262252769d6138a29b35b70.1470219853.git.vdavydov@virtuozzo.com
Signed-off-by: Vladimir Davydov <vdavydov@virtuozzo.com>
Acked-by: Johannes Weiner <hannes@cmpxchg.org>
Acked-by: Michal Hocko <mhocko@suse.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Vladimir Davydov 2016-10-07 16:57:29 -07:00 committed by Linus Torvalds
parent 252e5c6e2e
commit 58fa2a5512
1 changed files with 5 additions and 1 deletions
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6
mm/memcontrol.c
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@ -4062,11 +4062,13 @@ static DEFINE_IDR(mem_cgroup_idr);
static void mem_cgroup_id_get_many(struct mem_cgroup *memcg, unsigned int n) 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); atomic_add(n, &memcg->id.ref);
} }
static void mem_cgroup_id_put_many(struct mem_cgroup *memcg, unsigned int n) 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)) { if (atomic_sub_and_test(n, &memcg->id.ref)) {
idr_remove(&mem_cgroup_idr, memcg->id.id); idr_remove(&mem_cgroup_idr, memcg->id.id);
memcg->id.id = 0; memcg->id.id = 0;
@ -4255,8 +4257,10 @@ fail:
static int mem_cgroup_css_online(struct cgroup_subsys_state *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 */ /* 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); css_get(css);
return 0; return 0;
} }