From mboxrd@z Thu Jan 1 00:00:00 1970 From: Coly Li Subject: [PATCH] bcache: set task state correctly in allocator_wait() Date: Wed, 22 Nov 2017 20:33:49 +0800 Message-ID: <20171122123349.74347-1-colyli@suse.de> Return-path: Received: from mx2.suse.de ([195.135.220.15]:60382 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752325AbdKVMd6 (ORCPT ); Wed, 22 Nov 2017 07:33:58 -0500 Sender: linux-bcache-owner@vger.kernel.org List-Id: linux-bcache@vger.kernel.org To: linux-bcache@vger.kernel.org Cc: linux-block@vger.kernel.org, Coly Li , stable@vger.kernel.org Kthread function bch_allocator_thread() references allocator_wait(ca, cond) and when kthread_should_stop() is true, this kthread exits. The problem is, if kthread_should_stop() is true, macro allocator_wait() calls "return 0" with current task state TASK_INTERRUPTIBLE. After function bch_allocator_thread() returns to do_exit(), there are some blocking operations are called, then a kenrel warning is popped up by __might_sleep from kernel/sched/core.c, "WARNING: do not call blocking ops when !TASK_RUNNING; state=1 set at [xxxx]" If the task is interrupted and preempted out, since its status is TASK_INTERRUPTIBLE, it means scheduler won't pick it back to run forever, and the allocator thread may hang in do_exit(). This patch sets allocator kthread state back to TASK_RUNNING before it returns to do_exit(), which avoids a potential deadlock. Signed-off-by: Coly Li Cc: stable@vger.kernel.org --- drivers/md/bcache/alloc.c | 5 ++++- 1 file changed, 4 insertions(+), 1 deletion(-) diff --git a/drivers/md/bcache/alloc.c b/drivers/md/bcache/alloc.c index a27d85232ce1..996ebbabd819 100644 --- a/drivers/md/bcache/alloc.c +++ b/drivers/md/bcache/alloc.c @@ -286,9 +286,12 @@ do { \ if (cond) \ break; \ \ + \ mutex_unlock(&(ca)->set->bucket_lock); \ - if (kthread_should_stop()) \ + if (kthread_should_stop()) { \ + __set_current_state(TASK_RUNNING); \ return 0; \ + } \ \ schedule(); \ mutex_lock(&(ca)->set->bucket_lock); \ -- 2.13.6