Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752577AbbHEJvw (ORCPT ); Wed, 5 Aug 2015 05:51:52 -0400 Received: from mail-wi0-f179.google.com ([209.85.212.179]:35587 "EHLO mail-wi0-f179.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752450AbbHEJvs (ORCPT ); Wed, 5 Aug 2015 05:51:48 -0400 From: mhocko@kernel.org To: LKML Cc: , , Andrew Morton , Johannes Weiner , Tetsuo Handa , Dave Chinner , "Theodore Ts'o" , linux-btrfs@vger.kernel.org, linux-ext4@vger.kernel.org, Jan Kara , Michal Hocko Subject: [RFC 1/8] mm, oom: Give __GFP_NOFAIL allocations access to memory reserves Date: Wed, 5 Aug 2015 11:51:17 +0200 Message-Id: <1438768284-30927-2-git-send-email-mhocko@kernel.org> X-Mailer: git-send-email 2.5.0 In-Reply-To: <1438768284-30927-1-git-send-email-mhocko@kernel.org> References: <1438768284-30927-1-git-send-email-mhocko@kernel.org> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1903 Lines: 50 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. Signed-off-by: Michal Hocko --- mm/page_alloc.c | 10 +++++++++- 1 file changed, 9 insertions(+), 1 deletion(-) diff --git a/mm/page_alloc.c b/mm/page_alloc.c index 1f9ffbb087cb..ee69c338ca2a 100644 --- a/mm/page_alloc.c +++ b/mm/page_alloc.c @@ -2732,8 +2732,16 @@ __alloc_pages_may_oom(gfp_t gfp_mask, unsigned int order, } /* Exhausted what can be done so it's blamo time */ if (out_of_memory(ac->zonelist, gfp_mask, order, ac->nodemask, false) - || WARN_ON_ONCE(gfp_mask & __GFP_NOFAIL)) + || 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); + WARN_ONCE(!page, "Unable to fullfil gfp_nofail allocation." + " Consider increasing min_free_kbytes.\n"); + } + } out: mutex_unlock(&oom_lock); return page; -- 2.5.0 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/