From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755855AbcBWVzi (ORCPT ); Tue, 23 Feb 2016 16:55:38 -0500 Received: from shadbolt.e.decadent.org.uk ([88.96.1.126]:41702 "EHLO shadbolt.e.decadent.org.uk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755594AbcBWVo5 (ORCPT ); Tue, 23 Feb 2016 16:44:57 -0500 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, "Joonsoo Kim" , "Tetsuo Handa" , "Linus Torvalds" , "Cristopher Lameter" , "Michal Hocko" , "Tetsuo Handa" , "Jan Stancek" , "Arkadiusz Miskiewicz" , "Tejun Heo" Date: Tue, 23 Feb 2016 21:42:03 +0000 Message-ID: X-Mailer: LinuxStableQueue (scripts by bwh) Subject: [PATCH 3.2 47/67] mm, vmstat: fix wrong WQ sleep when memory reclaim doesn't make any progress In-Reply-To: X-SA-Exim-Connect-IP: 92.40.248.141 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 3.2.78-rc1 review patch. If anyone has any objections, please let me know. ------------------ From: Tetsuo Handa commit 564e81a57f9788b1475127012e0fd44e9049e342 upstream. Jan Stancek has reported that system occasionally hanging after "oom01" testcase from LTP triggers OOM. Guessing from a result that there is a kworker thread doing memory allocation and the values between "Node 0 Normal free:" and "Node 0 Normal:" differs when hanging, vmstat is not up-to-date for some reason. According to commit 373ccbe59270 ("mm, vmstat: allow WQ concurrency to discover memory reclaim doesn't make any progress"), it meant to force the kworker thread to take a short sleep, but it by error used schedule_timeout(1). We missed that schedule_timeout() in state TASK_RUNNING doesn't do anything. Fix it by using schedule_timeout_uninterruptible(1) which forces the kworker thread to take a short sleep in order to make sure that vmstat is up-to-date. Fixes: 373ccbe59270 ("mm, vmstat: allow WQ concurrency to discover memory reclaim doesn't make any progress") Signed-off-by: Tetsuo Handa Reported-by: Jan Stancek Acked-by: Michal Hocko Cc: Tejun Heo Cc: Cristopher Lameter Cc: Joonsoo Kim Cc: Arkadiusz Miskiewicz Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds Signed-off-by: Ben Hutchings --- mm/backing-dev.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) --- a/mm/backing-dev.c +++ b/mm/backing-dev.c @@ -879,7 +879,7 @@ long wait_iff_congested(struct zone *zon * here rather than calling cond_resched(). */ if (current->flags & PF_WQ_WORKER) - schedule_timeout(1); + schedule_timeout_uninterruptible(1); else cond_resched();