From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-wm0-f48.google.com (mail-wm0-f48.google.com [74.125.82.48]) by kanga.kvack.org (Postfix) with ESMTP id B00616B0254 for ; Wed, 25 Nov 2015 05:41:04 -0500 (EST) Received: by wmww144 with SMTP id w144so63425172wmw.0 for ; Wed, 25 Nov 2015 02:41:04 -0800 (PST) Received: from mail-wm0-f52.google.com (mail-wm0-f52.google.com. [74.125.82.52]) by mx.google.com with ESMTPS id qp9si33659992wjc.189.2015.11.25.02.41.01 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Wed, 25 Nov 2015 02:41:02 -0800 (PST) Received: by wmww144 with SMTP id w144so174260039wmw.1 for ; Wed, 25 Nov 2015 02:41:01 -0800 (PST) From: Michal Hocko Subject: [PATCH 1/2] mm, oom: Give __GFP_NOFAIL allocations access to memory reserves Date: Wed, 25 Nov 2015 11:40:53 +0100 Message-Id: <1448448054-804-2-git-send-email-mhocko@kernel.org> In-Reply-To: <1448448054-804-1-git-send-email-mhocko@kernel.org> References: <1448448054-804-1-git-send-email-mhocko@kernel.org> Sender: owner-linux-mm@kvack.org List-ID: To: Andrew Morton Cc: Mel Gorman , David Rientjes , Johannes Weiner , linux-mm@kvack.org, LKML , Michal Hocko 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 | 7 ++++++- 1 file changed, 6 insertions(+), 1 deletion(-) diff --git a/mm/page_alloc.c b/mm/page_alloc.c index 8034909faad2..70db11c27046 100644 --- a/mm/page_alloc.c +++ b/mm/page_alloc.c @@ -2766,8 +2766,13 @@ __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); + } out: mutex_unlock(&oom_lock); return page; -- 2.6.2 -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org