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From:   Z qiang <qiang.zhang1211@gmail.com>
Date:   Tue, 11 Jul 2023 12:01:48 +0800
Message-ID: <CALm+0cUurycz1=pt85sChA2dpzhk3KNLmTo5vfSb_uObOxQPRQ@mail.gmail.com>
Subject: Re: [syzbot] WARNING in kthread_bind_mask
To:     Tejun Heo <tj@kernel.org>
Cc:     syzbot <syzbot+087b7effddeec0697c66@syzkaller.appspotmail.com>,
        linux-kernel@vger.kernel.org, syzkaller-bugs@googlegroups.com
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>On Tue, Jul 11, 2023 at 6:07=E2=80=AFAM Sean Christopherson <seanjc@google=
.com> wrote:
>
> Trimmed the Cc list to avoid annoying folks with my thread necromancy.
>
> On Sun, Feb 20, 2022, 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=3D11daf74a700=
000
> > kernel config:  https://syzkaller.appspot.com/x/.config?x=3Dda674567f7b=
6043d
> > dashboard link: https://syzkaller.appspot.com/bug?extid=3D087b7effddeec=
0697c66
> > compiler:       gcc (Debian 10.2.1-6) 10.2.1 20210110, GNU ld (GNU Binu=
tils 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 co=
mmit:
> > 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 ]------------
>

Cc: Tejun

Full email path here:
https://lore.kernel.org/all/0000000000005ca92705d877448c@google.com/T/
https://syzkaller.appspot.com/bug?extid=3D087b7effddeec0697c66


static void __kthread_bind_mask(struct task_struct *p, const struct
cpumask *mask, unsigned int state)
{
        unsigned long flags;

        if (!wait_task_inactive(p, state)) {
                WARN_ON(1);      <--------------------------trigger warning
                return;
        }
....
}

Inconsistent task state trigger WARN_ON().


Thanks
Zqiang


>
> Dropping the "kvm" label as this isn't a KVM bug, but rather something in=
 either
> workqueues or sched that KVM often triggers through its use of alloc_work=
queue().
>
> #syz set subsystems: kernel