From: Vladimir Davydov <vdavydov@xxxxxxxxxxxxx> Subject: mm: memcontrol: add sanity checks for memcg->id.ref on get/put Link: http://lkml.kernel.org/r/1c5ddb1c171dbdfc3262252769d6138a29b35b70.1470219853.git.vdavydov@xxxxxxxxxxxxx Signed-off-by: Vladimir Davydov <vdavydov@xxxxxxxxxxxxx> Acked-by: Johannes Weiner <hannes@xxxxxxxxxxx> Acked-by: Michal Hocko <mhocko@xxxxxxxx> Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> --- mm/memcontrol.c | 6 +++++- 1 file changed, 5 insertions(+), 1 deletion(-) diff -puN mm/memcontrol.c~mm-memcontrol-add-sanity-checks-for-memcg-idref-on-get-put mm/memcontrol.c --- a/mm/memcontrol.c~mm-memcontrol-add-sanity-checks-for-memcg-idref-on-get-put +++ a/mm/memcontrol.c @@ -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; } _ -- To unsubscribe from this list: send the line "unsubscribe mm-commits" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
