Messages in this thread Patch in this message | | | From | Vladimir Davydov <> | Subject | [PATCH 3/3] mm: memcontrol: add sanity checks for memcg->id.ref on get/put | Date | Mon, 1 Aug 2016 16:26:26 +0300 |
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Signed-off-by: Vladimir Davydov <vdavydov@virtuozzo.com> --- mm/memcontrol.c | 8 ++++++-- 1 file changed, 6 insertions(+), 2 deletions(-)
diff --git a/mm/memcontrol.c b/mm/memcontrol.c index 58c229071fb1..cf7fb63860e5 100644 --- a/mm/memcontrol.c +++ b/mm/memcontrol.c @@ -4032,18 +4032,22 @@ 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 struct mem_cgroup *mem_cgroup_id_get_active(struct mem_cgroup *memcg) { - while (!atomic_inc_not_zero(&memcg->id.ref)) + while (!atomic_inc_not_zero(&memcg->id.ref)) { + VM_BUG_ON(mem_cgroup_is_root(memcg)); memcg = parent_mem_cgroup(memcg); + } return memcg; } 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; @@ -4164,6 +4168,7 @@ static struct mem_cgroup *mem_cgroup_alloc(void) INIT_LIST_HEAD(&memcg->cgwb_list); #endif idr_replace(&mem_cgroup_idr, memcg, memcg->id.id); + atomic_set(&memcg->id.ref, 1); return memcg; fail: if (memcg->id.id > 0) @@ -4233,7 +4238,6 @@ fail: static int mem_cgroup_css_online(struct cgroup_subsys_state *css) { /* Online state pins memcg ID, memcg ID pins CSS */ - mem_cgroup_id_get(mem_cgroup_from_css(css)); css_get(css); return 0; } -- 2.1.4
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