linux-kernel - Re: [syzbot] [ceph?] [fs?] INFO: task hung in ceph_mdsc_pre

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Date: Wed,  7 Feb 2024 18:58:01 +0800
From: Hillf Danton <hdanton@...a.com>
To: syzbot <syzbot+4bbc13a207327f82b3b0@...kaller.appspotmail.com>
Cc: linux-kernel@...r.kernel.org,
	syzkaller-bugs@...glegroups.com
Subject: Re: [syzbot] [ceph?] [fs?] INFO: task hung in ceph_mdsc_pre_umount

On Mon, 05 Feb 2024 08:43:25 -0800
> HEAD commit:    076d56d74f17 Add linux-next specific files for 20240202
> git tree:       linux-next
> C reproducer:   https://syzkaller.appspot.com/x/repro.c?x=1255e7c4180000

#syz test https://git.kernel.org/pub/scm/linux/kernel/git/next/linux-next.git  076d56d74f17

--- a/kernel/workqueue.c
+++ b/kernel/workqueue.c
@@ -1999,6 +1999,8 @@ static int try_to_grab_pending(struct wo
 	 */
 	pwq = get_work_pwq(work);
 	if (pwq && pwq->pool == pool) {
+		unsigned long work_data;
+
 		debug_work_deactivate(work);
 
 		/*
@@ -2016,11 +2018,12 @@ static int try_to_grab_pending(struct wo
 
 		list_del_init(&work->entry);
 
+		work_data = *work_data_bits(work);
 		/* work->data points to pwq iff queued, point to pool */
 		set_work_pool_and_keep_pending(work, pool->id);
 
 		/* must be the last step, see the function comment */
-		pwq_dec_nr_in_flight(pwq, *work_data_bits(work));
+		pwq_dec_nr_in_flight(pwq, work_data);
 
 		raw_spin_unlock(&pool->lock);
 		rcu_read_unlock();
--