Re: [syzbot] WARNING in mntput_no_expire (3)

[Al Viro]

On Wed, May 18, 2022 at 12:59:46AM +0000, Al Viro wrote:
> On Tue, May 17, 2022 at 10:58:15PM +0000, Al Viro wrote:
> > On Tue, May 17, 2022 at 03:49:07PM -0700, syzbot wrote:
> > > Hello,
> > > 
> > > syzbot has tested the proposed patch but the reproducer is still triggering an issue:
> > > WARNING in mntput_no_expire
> > 
> > Obvious question: which filesystem it is?
> 
> FWIW, can't reproduce here - at least not with C reproducer +
> -rc7^ kernel + .config from report + debian kvm image (bullseye,
> with systemd shite replaced with sysvinit, which might be relevant).
> 
> In case systemd-specific braindamage is needed to reproduce it...
> Hell knows; at least mount --make-rshared / doesn't seem to suffice.

... doesn't reproduce with genuine systemd either.  FWIW, 4-way SMP
setup here.