From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1758717AbbLBPNX (ORCPT ); Wed, 2 Dec 2015 10:13:23 -0500 Received: from mail-wm0-f51.google.com ([74.125.82.51]:35181 "EHLO mail-wm0-f51.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753447AbbLBPNV (ORCPT ); Wed, 2 Dec 2015 10:13:21 -0500 From: Michal Hocko To: Andrew Morton Cc: David Rientjes , Johannes Weiner , Mel Gorman , , LKML , Michal Hocko Subject: [PATCH v2] mm, oom: Give __GFP_NOFAIL allocations access to memory reserves Date: Wed, 2 Dec 2015 16:13:10 +0100 Message-Id: <1449069190-7325-1-git-send-email-mhocko@kernel.org> X-Mailer: git-send-email 2.6.2 In-Reply-To: <1448448054-804-2-git-send-email-mhocko@kernel.org> References: <1448448054-804-2-git-send-email-mhocko@kernel.org> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Michal Hocko __GFP_NOFAIL is a big hammer used to ensure that the allocation request can never fail. This is a strong requirement and as such it also deserves a special treatment when the system is OOM. The primary problem here is that the allocation request might have come with some locks held and the oom victim might be blocked on the same locks. This is basically an OOM deadlock situation. This patch tries to reduce the risk of such a deadlocks by giving __GFP_NOFAIL allocations a special treatment and let them dive into memory reserves after oom killer invocation. This should help them to make a progress and release resources they are holding. The OOM victim should compensate for the reserves consumption. Suggested-by: Andrea Arcangeli Signed-off-by: Michal Hocko --- mm/page_alloc.c | 15 ++++++++++++++- 1 file changed, 14 insertions(+), 1 deletion(-) diff --git a/mm/page_alloc.c b/mm/page_alloc.c index 8034909faad2..367523b2948b 100644 --- a/mm/page_alloc.c +++ b/mm/page_alloc.c @@ -2766,8 +2766,21 @@ __alloc_pages_may_oom(gfp_t gfp_mask, unsigned int order, goto out; } /* Exhausted what can be done so it's blamo time */ - if (out_of_memory(&oc) || WARN_ON_ONCE(gfp_mask & __GFP_NOFAIL)) + if (out_of_memory(&oc) || WARN_ON_ONCE(gfp_mask & __GFP_NOFAIL)) { *did_some_progress = 1; + + if (gfp_mask & __GFP_NOFAIL) { + page = get_page_from_freelist(gfp_mask, order, + ALLOC_NO_WATERMARKS|ALLOC_CPUSET, ac); + /* + * fallback to ignore cpuset restriction if our nodes + * are depleted + */ + if (!page) + page = get_page_from_freelist(gfp_mask, order, + ALLOC_NO_WATERMARKS, ac); + } + } out: mutex_unlock(&oom_lock); return page; -- 2.6.2