Commit 564e81a5 authored by Tetsuo Handa's avatar Tetsuo Handa Committed by Linus Torvalds

mm, vmstat: fix wrong WQ sleep when memory reclaim doesn't make any progress

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 373ccbe5 ("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: 373ccbe5 ("mm, vmstat: allow WQ concurrency to discover memory reclaim doesn't make any progress")
Signed-off-by: default avatarTetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
Reported-by: default avatarJan Stancek <jstancek@redhat.com>
Acked-by: default avatarMichal Hocko <mhocko@suse.com>
Cc: Tejun Heo <tj@kernel.org>
Cc: Cristopher Lameter <clameter@sgi.com>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: Arkadiusz Miskiewicz <arekm@maven.pl>
Cc: <stable@vger.kernel.org>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent ccde8bd4
...@@ -989,7 +989,7 @@ long wait_iff_congested(struct zone *zone, int sync, long timeout) ...@@ -989,7 +989,7 @@ long wait_iff_congested(struct zone *zone, int sync, long timeout)
* here rather than calling cond_resched(). * here rather than calling cond_resched().
*/ */
if (current->flags & PF_WQ_WORKER) if (current->flags & PF_WQ_WORKER)
schedule_timeout(1); schedule_timeout_uninterruptible(1);
else else
cond_resched(); cond_resched();
......
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