RE: kernel panics with 4.14.X versions

[Dexuan Cui]

> From: Greg KH <greg@xxxxxxxxx>
> Sent: Tuesday, April 17, 2018 03:34
> On Mon, Apr 16, 2018 at 09:10:35PM +0000, Dexuan Cui wrote:
> > > From: Jan Kara <jack@xxxxxxx>
> > > Sent: Monday, April 16, 2018 07:41
> > > ...
> > > How easily can you hit this? Are you able to run debug kernels / inspect
> > > crash dumps when the issue occurs? Also testing with the latest mainline
> > > 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 actually
> > 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
> 
> Any chance to run 'git bisect' between 4.14 and 4.15 to find the fix?
> greg k-h

Sorry, I'm afraid not. 
It was only reproducible in a customer VM with a specific workload and it took
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