From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751761AbdEJGyE (ORCPT ); Wed, 10 May 2017 02:54:04 -0400 Received: from mail-pf0-f194.google.com ([209.85.192.194]:35459 "EHLO mail-pf0-f194.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751508AbdEJGyC (ORCPT ); Wed, 10 May 2017 02:54:02 -0400 From: Nick Desaulniers Cc: akpm@linux-foundation.org, hannes@cmpxchg.org, mgorman@techsingularity.net, mhocko@suse.com, vbabka@suse.cz, minchan@kernel.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org, Nick Desaulniers Subject: [PATCH] mm/vmscan: fix unsequenced modification and access warning Date: Tue, 9 May 2017 23:53:28 -0700 Message-Id: <20170510065328.9215-1-nick.desaulniers@gmail.com> X-Mailer: git-send-email 2.11.0 To: unlisted-recipients:; (no To-header on input) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Clang flags this file with the -Wunsequenced error that GCC does not have. unsequenced modification and access to 'gfp_mask' It seems that gfp_mask is both read and written without a sequence point in between, which is undefined behavior. Signed-off-by: Nick Desaulniers --- mm/vmscan.c | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-) diff --git a/mm/vmscan.c b/mm/vmscan.c index 4e7ed65842af..74785908822c 100644 --- a/mm/vmscan.c +++ b/mm/vmscan.c @@ -2958,7 +2958,7 @@ unsigned long try_to_free_pages(struct zonelist *zonelist, int order, unsigned long nr_reclaimed; struct scan_control sc = { .nr_to_reclaim = SWAP_CLUSTER_MAX, - .gfp_mask = (gfp_mask = current_gfp_context(gfp_mask)), + .gfp_mask = current_gfp_context(gfp_mask), .reclaim_idx = gfp_zone(gfp_mask), .order = order, .nodemask = nodemask, @@ -2968,6 +2968,8 @@ unsigned long try_to_free_pages(struct zonelist *zonelist, int order, .may_swap = 1, }; + gfp_mask = sc.gfp_mask; + /* * Do not enter reclaim if fatal signal was delivered while throttled. * 1 is returned so that the page allocator does not OOM kill at this -- 2.11.0