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memcg: remove memcg_cgroup::id from IDR on mem_cgroup_css_alloc() failure 

In case of memcg_online_kmem() failure, memcg_cgroup::id remains hashed
in mem_cgroup_idr even after memcg memory is freed.  This leads to leak
of ID in mem_cgroup_idr.

This patch adds removal into mem_cgroup_css_alloc(), which fixes the
problem.  For better readability, it adds a generic helper which is used
in mem_cgroup_alloc() and mem_cgroup_id_put_many() as well.

Link: http://lkml.kernel.org/r/152354470916.22460.14397070748001974638.stgit@localhost.localdomain
Fixes 73f576c04b ("mm: memcontrol: fix cgroup creation failure after many small jobs")
Signed-off-by: Kirill Tkhai <ktkhai@virtuozzo.com>
Acked-by: Johannes Weiner <hannes@cmpxchg.org>
Acked-by: Vladimir Davydov <vdavydov.dev@gmail.com>
Cc: Michal Hocko <mhocko@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Kirill Tkhai 2018-08-02 15:36:01 -07:00 committed by Linus Torvalds
parent e30cb13c5a
commit 7e97de0b03
1 changed files with 11 additions and 4 deletions
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15
mm/memcontrol.c
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@ -4037,6 +4037,14 @@ static struct cftype mem_cgroup_legacy_files[] = {
static DEFINE_IDR(mem_cgroup_idr);
static void mem_cgroup_id_remove(struct mem_cgroup *memcg)
{
if (memcg->id.id > 0) {
idr_remove(&mem_cgroup_idr, memcg->id.id);
memcg->id.id = 0;
}
}
static void mem_cgroup_id_get_many(struct mem_cgroup *memcg, unsigned int n)
{
VM_BUG_ON(atomic_read(&memcg->id.ref) <= 0);
@ -4047,8 +4055,7 @@ 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;
mem_cgroup_id_remove(memcg);
/* Memcg ID pins CSS */
css_put(&memcg->css);
@ -4185,8 +4192,7 @@ static struct mem_cgroup *mem_cgroup_alloc(void)
idr_replace(&mem_cgroup_idr, memcg, memcg->id.id);
return memcg;
fail:
if (memcg->id.id > 0)
idr_remove(&mem_cgroup_idr, memcg->id.id);
mem_cgroup_id_remove(memcg);
__mem_cgroup_free(memcg);
return NULL;
}
@ -4245,6 +4251,7 @@ mem_cgroup_css_alloc(struct cgroup_subsys_state *parent_css)
return &memcg->css;
fail:
mem_cgroup_id_remove(memcg);
mem_cgroup_free(memcg);
return ERR_PTR(-ENOMEM);
}