Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751881AbbKKNsd (ORCPT ); Wed, 11 Nov 2015 08:48:33 -0500 Received: from mail-wm0-f45.google.com ([74.125.82.45]:34834 "EHLO mail-wm0-f45.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750778AbbKKNsc (ORCPT ); Wed, 11 Nov 2015 08:48:32 -0500 From: mhocko@kernel.org To: Andrew Morton Cc: Johannes Weiner , Andrea Arcangeli , Mel Gorman , David Rientjes , , LKML , Michal Hocko Subject: [PATCH] mm, oom: Give __GFP_NOFAIL allocations access to memory reserves Date: Wed, 11 Nov 2015 14:48:17 +0100 Message-Id: <1447249697-13380-1-git-send-email-mhocko@kernel.org> X-Mailer: git-send-email 2.6.2 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2238 Lines: 60 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 --- Hi, this has been posted previously as a part of larger GFP_NOFS related patch set (http://lkml.kernel.org/r/1438768284-30927-1-git-send-email-mhocko%40kernel.org) but Andrea was asking basically the same thing at LSF early this year (I cannot seem to find it in any public archive though). I think the patch makes some sense on its own. Comments? 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 8034909faad2..d30bce9d7ac8 100644 --- a/mm/page_alloc.c +++ b/mm/page_alloc.c @@ -2766,8 +2766,16 @@ __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); + WARN_ONCE(!page, "Unable to fullfil gfp_nofail allocation." + " Consider increasing min_free_kbytes.\n"); + } + } out: mutex_unlock(&oom_lock); return page; -- 2.6.2 -- 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/