Re: [syzbot] [fuse?] WARNING: refcount bug in process_scheduled_works

[Hillf Danton <hdanton@sina.com>]

> Date: Tue, 29 Jul 2025 14:58:32 -0700	[thread overview]
> Hello,
> 
> syzbot found the following issue on:
> 
> HEAD commit:    ced1b9e0392d Merge tag 'ata-6.17-rc1' of git://git.kernel...
> git tree:       upstream
> console+strace: https://syzkaller.appspot.com/x/log.txt?x=15c89782580000
> kernel config:  https://syzkaller.appspot.com/x/.config?x=d51af648924b64c9
> dashboard link: https://syzkaller.appspot.com/bug?extid=9921e319bd6168140b40
> syz repro:      https://syzkaller.appspot.com/x/repro.syz?x=177f7034580000
> C reproducer:   https://syzkaller.appspot.com/x/repro.c?x=165e44a2580000

Test Yu Kuai's fix (https://lore.kernel.org/lkml/20250730073321.2583158-1-yukuai1@huaweicloud.com/)

#syz test

--- a/drivers/md/md.c
+++ b/drivers/md/md.c
@@ -636,6 +636,12 @@ static void __mddev_put(struct mddev *mddev)
 	    mddev->ctime || mddev->hold_active)
 		return;
 
+	/*
+	 * If array is freed by stopping array, MD_DELETED is set by
+	 * do_md_stop(), MD_DELETED is still set here in cause mddev is freed
+	 * directly by closing a mddev that is created by create_on_open.
+	 */
+	set_bit(MD_DELETED, &mddev->flags);
 	/*
 	 * Call queue_work inside the spinlock so that flush_workqueue() after
 	 * mddev_find will succeed in waiting for the work to be done.
--