From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756260AbaIKNKW (ORCPT ); Thu, 11 Sep 2014 09:10:22 -0400 Received: from shadbolt.e.decadent.org.uk ([88.96.1.126]:52280 "EHLO shadbolt.e.decadent.org.uk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753371AbaIKNE3 (ORCPT ); Thu, 11 Sep 2014 09:04:29 -0400 Content-Type: text/plain; charset="UTF-8" Content-Disposition: inline Content-Transfer-Encoding: 8bit MIME-Version: 1.0 From: Ben Hutchings To: linux-kernel@vger.kernel.org, stable@vger.kernel.org CC: akpm@linux-foundation.org, "Alex Thorlton" , "Hugh Dickins" , "Kirill A. Shutemov" , "Dave Hansen" , "David Rientjes" , "Mel Gorman" , "Bob Liu" , "Hedi Berriche" , "Srivatsa S. Bhat" , "Johannes Weiner" , "Rik van Riel" , "Linus Torvalds" Date: Thu, 11 Sep 2014 13:32:13 +0100 Message-ID: X-Mailer: LinuxStableQueue (scripts by bwh) Subject: [PATCH 3.2 031/131] mm, thp: do not allow thp faults to avoid cpuset restrictions In-Reply-To: X-SA-Exim-Connect-IP: 192.168.4.249 X-SA-Exim-Mail-From: ben@decadent.org.uk X-SA-Exim-Scanned: No (on shadbolt.decadent.org.uk); SAEximRunCond expanded to false Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 3.2.63-rc1 review patch. If anyone has any objections, please let me know. ------------------ From: David Rientjes commit b104a35d32025ca740539db2808aa3385d0f30eb upstream. The page allocator relies on __GFP_WAIT to determine if ALLOC_CPUSET should be set in allocflags. ALLOC_CPUSET controls if a page allocation should be restricted only to the set of allowed cpuset mems. Transparent hugepages clears __GFP_WAIT when defrag is disabled to prevent the fault path from using memory compaction or direct reclaim. Thus, it is unfairly able to allocate outside of its cpuset mems restriction as a side-effect. This patch ensures that ALLOC_CPUSET is only cleared when the gfp mask is truly GFP_ATOMIC by verifying it is also not a thp allocation. Signed-off-by: David Rientjes Reported-by: Alex Thorlton Tested-by: Alex Thorlton Cc: Bob Liu Cc: Dave Hansen Cc: Hedi Berriche Cc: Hugh Dickins Cc: Johannes Weiner Cc: Kirill A. Shutemov Cc: Mel Gorman Cc: Rik van Riel Cc: Srivatsa S. Bhat Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds Signed-off-by: Ben Hutchings --- mm/page_alloc.c | 16 ++++++++-------- 1 file changed, 8 insertions(+), 8 deletions(-) --- a/mm/page_alloc.c +++ b/mm/page_alloc.c @@ -2054,7 +2054,7 @@ static inline int gfp_to_alloc_flags(gfp_t gfp_mask) { int alloc_flags = ALLOC_WMARK_MIN | ALLOC_CPUSET; - const gfp_t wait = gfp_mask & __GFP_WAIT; + const bool atomic = !(gfp_mask & (__GFP_WAIT | __GFP_NO_KSWAPD)); /* __GFP_HIGH is assumed to be the same as ALLOC_HIGH to save a branch. */ BUILD_BUG_ON(__GFP_HIGH != (__force gfp_t) ALLOC_HIGH); @@ -2063,20 +2063,20 @@ gfp_to_alloc_flags(gfp_t gfp_mask) * The caller may dip into page reserves a bit more if the caller * cannot run direct reclaim, or if the caller has realtime scheduling * policy or is asking for __GFP_HIGH memory. GFP_ATOMIC requests will - * set both ALLOC_HARDER (!wait) and ALLOC_HIGH (__GFP_HIGH). + * set both ALLOC_HARDER (atomic == true) and ALLOC_HIGH (__GFP_HIGH). */ alloc_flags |= (__force int) (gfp_mask & __GFP_HIGH); - if (!wait) { + if (atomic) { /* - * Not worth trying to allocate harder for - * __GFP_NOMEMALLOC even if it can't schedule. + * Not worth trying to allocate harder for __GFP_NOMEMALLOC even + * if it can't schedule. */ - if (!(gfp_mask & __GFP_NOMEMALLOC)) + if (!(gfp_mask & __GFP_NOMEMALLOC)) alloc_flags |= ALLOC_HARDER; /* - * Ignore cpuset if GFP_ATOMIC (!wait) rather than fail alloc. - * See also cpuset_zone_allowed() comment in kernel/cpuset.c. + * Ignore cpuset mems for GFP_ATOMIC rather than fail, see the + * comment for __cpuset_node_allowed_softwall(). */ alloc_flags &= ~ALLOC_CPUSET; } else if (unlikely(rt_task(current)) && !in_interrupt())