On Mon, Oct 19, 2020 at 12:03 AM Dae R. Jeong <dae.r.jeong@xxxxxxxxxxx> wrote: > > > diff --git i/drivers/md/md.c w/drivers/md/md.c > > index 6072782070230..49442a3f4605b 100644 > > --- i/drivers/md/md.c > > +++ w/drivers/md/md.c > > @@ -7591,8 +7591,10 @@ static int md_ioctl(struct block_device *bdev, > > fmode_t mode, > > err = -EBUSY; > > goto out; > > } > > - WARN_ON_ONCE(test_bit(MD_CLOSING, &mddev->flags)); > > - set_bit(MD_CLOSING, &mddev->flags); > > + if (test_and_set_bit(MD_CLOSING, &mddev->flags)) { > > + err = -EBUSY; > > + goto out; > > + } > > did_set_md_closing = true; > > mutex_unlock(&mddev->open_mutex); > > sync_blockdev(bdev); > > > > Could you please test whether this fixes the issue? > > Since &mddev->open_mutex is held when testing a bit of mddev->flags, I > modified the code just a little bit by putting mutex_unlock() as > belows. Good catch! The fix looks good. Would you like to submit a patch for it? Thanks, Song