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Date:   Mon, 21 Feb 2022 15:23:58 +0100
From:   David Sterba <dsterba@suse.cz>
To:     syzbot <syzbot+087b7effddeec0697c66@syzkaller.appspotmail.com>
Cc:     clm@fb.com, dsterba@suse.com, josef@toxicpanda.com,
        linux-btrfs@vger.kernel.org, linux-kernel@vger.kernel.org,
        syzkaller-bugs@googlegroups.com
Subject: Re: [syzbot] WARNING in kthread_bind_mask
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On Sun, Feb 20, 2022 at 10:27:23AM -0800, syzbot wrote:
> Hello,
> 
> syzbot found the following issue on:
> 
> HEAD commit:    c5d9ae265b10 Merge tag 'for-linus' of git://git.kernel.org..
> git tree:       upstream
> console output: https://syzkaller.appspot.com/x/log.txt?x=11daf74a700000
> kernel config:  https://syzkaller.appspot.com/x/.config?x=da674567f7b6043d
> dashboard link: https://syzkaller.appspot.com/bug?extid=087b7effddeec0697c66
> compiler:       gcc (Debian 10.2.1-6) 10.2.1 20210110, GNU ld (GNU Binutils for Debian) 2.35.2
> 
> Unfortunately, I don't have any reproducer for this issue yet.
> 
> IMPORTANT: if you fix the issue, please add the following tag to the commit:
> Reported-by: syzbot+087b7effddeec0697c66@syzkaller.appspotmail.com
> 
> BTRFS info (device loop3): disk space caching is enabled
> BTRFS info (device loop3): has skinny extents
> ------------[ cut here ]------------
> WARNING: CPU: 0 PID: 10327 at kernel/kthread.c:525 __kthread_bind_mask kernel/kthread.c:525 [inline]

 520 static void __kthread_bind_mask(struct task_struct *p, const struct cpumask *mask, unsigned int state)
 521 {
 522         unsigned long flags;
 523
 524         if (!wait_task_inactive(p, state)) {
 525                 WARN_ON(1);
 526                 return;
 527         }

That seems to be some internal task state inconsistency.