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From:   Dexuan Cui <decui@microsoft.com>
To:     Greg KH <greg@kroah.com>
CC:     Jan Kara <jack@suse.cz>, Guillaume Morin <guillaume@morinfr.org>,
        Haiyang Zhang <haiyangz@microsoft.com>,
        Pavlos Parissis <pavlos.parissis@gmail.com>,
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        "jack@suse.com" <jack@suse.com>,
        "linux-fsdevel@vger.kernel.org" <linux-fsdevel@vger.kernel.org>,
        "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
        "mszeredi@redhat.com" <mszeredi@redhat.com>
Subject: RE: kernel panics with 4.14.X versions
Thread-Topic: kernel panics with 4.14.X versions
Thread-Index: AQHT1YZ2Fl4TtFRnH0qUyqkfz/cZJ6QDdryAgABq8lCAAOJjAIAAdoGw
Date:   Tue, 17 Apr 2018 17:42:38 +0000
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> From: Greg KH <greg@kroah.com>
> Sent: Tuesday, April 17, 2018 03:34
> On Mon, Apr 16, 2018 at 09:10:35PM +0000, Dexuan Cui wrote:
> > > From: Jan Kara <jack@suse.cz>
> > > Sent: Monday, April 16, 2018 07:41
> > > ...
> > > How easily can you hit this? Are you able to run debug kernels / insp=
ect
> > > crash dumps when the issue occurs? Also testing with the latest mainl=
ine
> > > kernel (4.16) would be welcome whether this isn't just an issue with =
the
> > > backport of fsnotify fixes from Miklos.
> >
> > It's not easy for us to reproduce the fsnotify() lockup issue, and actu=
ally
> > we still don't have an easy & reliable way to reproduce it.
> >
> > According to our tests, v4.16 doesn't have the issue.
> > And v4.15 doesn't have the issue either, if I recall correctly.
> > I only know the issue happens to v4.14.x and 4.13.x kernels
>=20
> Any chance to run 'git bisect' between 4.14 and 4.15 to find the fix?
> greg k-h

Sorry, I'm afraid not.=20
It was only reproducible in a customer VM with a specific workload and it t=
ook
days to hit the issue. The customer VM doesn't exist any more. And we even
can't find a way to reproduce the issue with fio tests + programs that test=
 fsnotify().

-- Dexuan