From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753952Ab3KNX1I (ORCPT ); Thu, 14 Nov 2013 18:27:08 -0500 Received: from mail-yh0-f49.google.com ([209.85.213.49]:60467 "EHLO mail-yh0-f49.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753802Ab3KNX0y (ORCPT ); Thu, 14 Nov 2013 18:26:54 -0500 Date: Thu, 14 Nov 2013 15:26:51 -0800 (PST) From: David Rientjes X-X-Sender: rientjes@chino.kir.corp.google.com To: Andrew Morton cc: Michal Hocko , Johannes Weiner , KAMEZAWA Hiroyuki , linux-kernel@vger.kernel.org, linux-mm@kvack.org, cgroups@vger.kernel.org Subject: [patch 1/2] mm, memcg: avoid oom notification when current needs access to memory reserves In-Reply-To: Message-ID: References: <20131031054942.GA26301@cmpxchg.org> <20131113233419.GJ707@cmpxchg.org> <20131114032508.GL707@cmpxchg.org> User-Agent: Alpine 2.02 (DEB 1266 2009-07-14) MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org When current has a pending SIGKILL or is already in the exit path, it only needs access to memory reserves to fully exit. In that sense, the memcg is not actually oom for current, it simply needs to bypass memory charges to exit and free its memory, which is guarantee itself that memory will be freed. We only want to notify userspace for actionable oom conditions where something needs to be done (and all oom handling can already be deferred to userspace through this method by disabling the memcg oom killer with memory.oom_control), not simply when a memcg has reached its limit, which would actually have to happen before memcg reclaim actually frees memory for charges. Reported-by: Johannes Weiner Signed-off-by: David Rientjes --- mm/memcontrol.c | 20 ++++++++++---------- 1 file changed, 10 insertions(+), 10 deletions(-) diff --git a/mm/memcontrol.c b/mm/memcontrol.c --- a/mm/memcontrol.c +++ b/mm/memcontrol.c @@ -1783,16 +1783,6 @@ static void mem_cgroup_out_of_memory(struct mem_cgroup *memcg, gfp_t gfp_mask, unsigned int points = 0; struct task_struct *chosen = NULL; - /* - * If current has a pending SIGKILL or is exiting, then automatically - * select it. The goal is to allow it to allocate so that it may - * quickly exit and free its memory. - */ - if (fatal_signal_pending(current) || current->flags & PF_EXITING) { - set_thread_flag(TIF_MEMDIE); - return; - } - check_panic_on_oom(CONSTRAINT_MEMCG, gfp_mask, order, NULL); totalpages = mem_cgroup_get_limit(memcg) >> PAGE_SHIFT ? : 1; for_each_mem_cgroup_tree(iter, memcg) { @@ -2243,6 +2233,16 @@ bool mem_cgroup_oom_synchronize(bool handle) if (!handle) goto cleanup; + /* + * If current has a pending SIGKILL or is exiting, then automatically + * select it. The goal is to allow it to allocate so that it may + * quickly exit and free its memory. + */ + if (fatal_signal_pending(current) || current->flags & PF_EXITING) { + set_thread_flag(TIF_MEMDIE); + goto cleanup; + } + owait.memcg = memcg; owait.wait.flags = 0; owait.wait.func = memcg_oom_wake_function;