From 95fc3c5010da8fd8bd3e2c8bc0fb9dc7606e3a3b Mon Sep 17 00:00:00 2001 From: Vladimir Davydov Date: Fri, 12 Dec 2014 16:54:56 -0800 Subject: [PATCH] memcg: do not abuse memcg_kmem_skip_account task_struct->memcg_kmem_skip_account was initially introduced to avoid recursion during kmem cache creation: memcg_kmem_get_cache, which is called by kmem_cache_alloc to determine the per-memcg cache to account allocation to, may issue lazy cache creation if the needed cache doesn't exist, which means issuing yet another kmem_cache_alloc. We can't just pass a flag to the nested kmem_cache_alloc disabling kmem accounting, because there are hidden allocations, e.g. in INIT_WORK. So we introduced a flag on the task_struct, memcg_kmem_skip_account, making memcg_kmem_get_cache return immediately. By its nature, the flag may also be used to disable accounting for allocations shared among different cgroups, and currently it is used this way in memcg_activate_kmem. Using it like this looks like abusing it to me. If we want to disable accounting for some allocations (which we will definitely want one day), we should either add GFP_NO_MEMCG or GFP_MEMCG flag in order to blacklist/whitelist some allocations. For now, let's simply remove memcg_stop/resume_kmem_account from memcg_activate_kmem. Signed-off-by: Vladimir Davydov Cc: Johannes Weiner Cc: Michal Hocko Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- mm/memcontrol.c | 7 ------- 1 file changed, 7 deletions(-) diff --git a/mm/memcontrol.c b/mm/memcontrol.c index 37f345e64fda..5a27e224d561 100644 --- a/mm/memcontrol.c +++ b/mm/memcontrol.c @@ -3538,12 +3538,6 @@ static int memcg_activate_kmem(struct mem_cgroup *memcg, if (memcg_kmem_is_active(memcg)) return 0; - /* - * We are going to allocate memory for data shared by all memory - * cgroups so let's stop accounting here. - */ - memcg_stop_kmem_account(); - /* * For simplicity, we won't allow this to be disabled. It also can't * be changed if the cgroup has children already, or if tasks had @@ -3588,7 +3582,6 @@ static int memcg_activate_kmem(struct mem_cgroup *memcg, */ memcg_kmem_set_active(memcg); out: - memcg_resume_kmem_account(); return err; } -- GitLab