From mboxrd@z Thu Jan 1 00:00:00 1970 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> Return-path: DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20161025; h=from:to:cc:subject:date:message-id; bh=Ii8pbkgyKnKKb8mIj9iKO/rsfe91Ujvj6+NbEtYEzkc=; b=HCsJYvaQYD1hNu8rrAKKmrOJMbL/UuHslAmnPzVugF9PKVXAj5/PNFbL2PbVwnPvWm OKqxlKUIr5otcIJmnQtfB6MRKpdhBqibXwGxedAOa07mXFQef36OsJKK///BmoxB6Awn k61fyU9t0sycX6q9fxfyczmBkeEDN0A8+CQ3BVQGVXpziSoCw1NNFZJSlEQlR2SIQpUn Q8TDuNtpj47jxbHOxUFDYlJBfP3DR9v7hFaXV3waGrwkQTYV1A5yFYfGzDe7Pm7ef+GC 8BSNFPnz5qpbkoIBu4g9s9T5/IKjHsfaPTIyAc84o0xbOije8RZs+qD08vebYm0qqwZf CPuA== Sender: linux-kernel-owner@vger.kernel.org List-ID: MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit 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