From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-pf0-f200.google.com (mail-pf0-f200.google.com [209.85.192.200]) by kanga.kvack.org (Postfix) with ESMTP id 3B85C6B0003 for ; Fri, 25 May 2018 14:55:09 -0400 (EDT) Received: by mail-pf0-f200.google.com with SMTP id x21-v6so3358200pfn.23 for ; Fri, 25 May 2018 11:55:09 -0700 (PDT) Received: from mail-sor-f65.google.com (mail-sor-f65.google.com. [209.85.220.65]) by mx.google.com with SMTPS id q1-v6sor10346859plr.28.2018.05.25.11.55.08 for (Google Transport Security); Fri, 25 May 2018 11:55:08 -0700 (PDT) From: Shakeel Butt Subject: [PATCH] memcg: force charge kmem counter too Date: Fri, 25 May 2018 11:55:01 -0700 Message-Id: <20180525185501.82098-1-shakeelb@google.com> Sender: owner-linux-mm@kvack.org List-ID: To: Michal Hocko , Andrew Morton , Greg Thelen , Johannes Weiner , Vladimir Davydov Cc: Linux MM , cgroups@vger.kernel.org, LKML , Shakeel Butt Based on several conditions the kernel can decide to force charge an allocation for a memcg i.e. overcharge memcg->memory and memcg->memsw counters. Do the same for memcg->kmem counter too. In cgroup-v1, this bug can cause a __GFP_NOFAIL kmem allocation fail if an explicit limit on kmem counter is set and reached. Signed-off-by: Shakeel Butt --- mm/memcontrol.c | 21 +++++++++++++++++++-- 1 file changed, 19 insertions(+), 2 deletions(-) diff --git a/mm/memcontrol.c b/mm/memcontrol.c index ab5673dbfc4e..0a88f824c550 100644 --- a/mm/memcontrol.c +++ b/mm/memcontrol.c @@ -1893,6 +1893,18 @@ void mem_cgroup_handle_over_high(void) current->memcg_nr_pages_over_high = 0; } +/* + * Based on try_charge() force charge conditions. + */ +static inline bool should_force_charge(gfp_t gfp_mask) +{ + return (unlikely(tsk_is_oom_victim(current) || + fatal_signal_pending(current) || + current->flags & PF_EXITING || + current->flags & PF_MEMALLOC || + gfp_mask & __GFP_NOFAIL)); +} + static int try_charge(struct mem_cgroup *memcg, gfp_t gfp_mask, unsigned int nr_pages) { @@ -2008,6 +2020,8 @@ static int try_charge(struct mem_cgroup *memcg, gfp_t gfp_mask, * The allocation either can't fail or will lead to more memory * being freed very soon. Allow memory usage go over the limit * temporarily by force charging it. + * + * NOTE: Please keep the should_force_charge() conditions in sync. */ page_counter_charge(&memcg->memory, nr_pages); if (do_memsw_account()) @@ -2331,8 +2345,11 @@ int memcg_kmem_charge_memcg(struct page *page, gfp_t gfp, int order, if (!cgroup_subsys_on_dfl(memory_cgrp_subsys) && !page_counter_try_charge(&memcg->kmem, nr_pages, &counter)) { - cancel_charge(memcg, nr_pages); - return -ENOMEM; + if (!should_force_charge(gfp)) { + cancel_charge(memcg, nr_pages); + return -ENOMEM; + } + page_counter_charge(&memcg->kmem, nr_pages); } page->mem_cgroup = memcg; -- 2.17.0.921.gf22659ad46-goog