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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 <[email protected]>
Acked-by: Johannes Weiner <[email protected]>
Acked-by: Michal Hocko <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>
This commit is contained in:
Vladimir Davydov authored and Linus Torvalds committed 2016-10-07 18:46:26 -07:00
1 parent 252e5c6e2e
commit 58fa2a5512
1 file changed
+5 -1
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mm/memcontrol.c
+5 -1
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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)
{
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 @@ fail:
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;
}