From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754044AbcEDOgf (ORCPT ); Wed, 4 May 2016 10:36:35 -0400 Received: from outbound-smtp05.blacknight.com ([81.17.249.38]:50570 "EHLO outbound-smtp05.blacknight.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752956AbcEDOgd (ORCPT ); Wed, 4 May 2016 10:36:33 -0400 Date: Wed, 4 May 2016 15:36:28 +0100 From: Mel Gorman To: Andrew Morton Cc: Vlastimil Babka , Jesper Dangaard Brouer , Linux-MM , LKML Subject: [PATCH] mm, page_alloc: Restore the original nodemask if the fast path allocation failed Message-ID: <20160504143628.GU2858@techsingularity.net> MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-15 Content-Disposition: inline User-Agent: Mutt/1.5.23 (2014-03-12) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org (Andrew, this is on top of the pagealloc optimisation series in mmotm. It could be classed as a fix-up but it's subtle enough that it deserves its own changelog. "Clever" fixes had other consequences.) The page allocator fast path uses either the requested nodemask or cpuset_current_mems_allowed if cpusets are enabled. If the allocation context allows watermarks to be ignored then it can also ignore memory policies. However, on entering the allocator slowpath the nodemask may still be cpuset_current_mems_allowed and the policies are enforced. This patch resets the nodemask appropriately before entering the slowpath. Signed-off-by: Vlastimil Babka Signed-off-by: Mel Gorman diff --git a/mm/page_alloc.c b/mm/page_alloc.c index 79100583b9de..ec5155ab1482 100644 --- a/mm/page_alloc.c +++ b/mm/page_alloc.c @@ -3637,6 +3637,12 @@ __alloc_pages_nodemask(gfp_t gfp_mask, unsigned int order, alloc_mask = memalloc_noio_flags(gfp_mask); ac.spread_dirty_pages = false; + /* + * Restore the original nodemask if it was potentially replaced with + * &cpuset_current_mems_allowed to optimize the fast-path attempt. + */ + if (cpusets_enabled()) + ac.nodemask = nodemask; page = __alloc_pages_slowpath(alloc_mask, order, &ac); no_zone: -- Mel Gorman SUSE Labs