| From foo@baz Sun Aug 26 09:13:00 CEST 2018 |
| From: Kirill Tkhai <ktkhai@virtuozzo.com> |
| Date: Thu, 2 Aug 2018 15:36:01 -0700 |
| Subject: memcg: remove memcg_cgroup::id from IDR on mem_cgroup_css_alloc() failure |
| |
| From: Kirill Tkhai <ktkhai@virtuozzo.com> |
| |
| [ Upstream commit 7e97de0b033bcac4fa9a35cef72e0c06e6a22c67 ] |
| |
| 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 73f576c04b94 ("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> |
| Signed-off-by: Sasha Levin <alexander.levin@microsoft.com> |
| Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> |
| --- |
| mm/memcontrol.c | 15 +++++++++++---- |
| 1 file changed, 11 insertions(+), 4 deletions(-) |
| |
| --- a/mm/memcontrol.c |
| +++ b/mm/memcontrol.c |
| @@ -4110,6 +4110,14 @@ static struct cftype mem_cgroup_legacy_f |
| |
| 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); |
| @@ -4120,8 +4128,7 @@ static void mem_cgroup_id_put_many(struc |
| { |
| 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); |
| @@ -4258,8 +4265,7 @@ static struct mem_cgroup *mem_cgroup_all |
| 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; |
| } |
| @@ -4318,6 +4324,7 @@ mem_cgroup_css_alloc(struct cgroup_subsy |
| |
| return &memcg->css; |
| fail: |
| + mem_cgroup_id_remove(memcg); |
| mem_cgroup_free(memcg); |
| return ERR_PTR(-ENOMEM); |
| } |