Re: Deadlock in fsnotify for

[Amir Goldstein <amir73il@gmail.com>]

On Fri, Sep 28, 2018 at 4:47 PM Nigel Banks <Nigel_Banks@waters.com> wrote:
>
> Hello Again,
>
> I've attached the kern.log as you instructed, please let me know if there is any more information I can provide.
>
>
>
> Cheers,
>
> Nigel
>
>
>
> From:        Jan Kara <jack@suse.cz>
> To:        Nigel Banks <Nigel_Banks@waters.com>
> Cc:        jack@suse.cz, linux-fsdevel@vger.kernel.org, Amir Goldstein <amir73il@gmail.com>
> Date:        09/27/2018 05:24 PM
> Subject:        Re: Deadlock in fsnotify for
> ________________________________
>
>
>
> Hello,
>
> [added to CC other relevant mails]
>
> On Thu 27-09-18 16:44:53, Nigel Banks wrote:
> > Sorry to trouble you, but from looking through the git history of linux/fs/
> > notify you seem to be the best person to contact.
> >
> > I've encounter a hard to reproduce situation that happens on our CI
> > servers, in which it becomes impossible to release any inotify file
> > descriptors. We're currently running Ubuntu 18.04 (Kernel 4.15) using
> > ext4 fs, and our code is running in docker containers (overlay2) if that
> > makes a difference.
> >

Nigel,

It actually could make a difference.
commit 764baba80168 ("ovl: hash non-dir by lower inode for fsnotify").
never made it to stable trees - it got stuck in the process:
https://www.spinics.net/lists/stable/msg250441.html

Can you check if Mark's backport patch (in the link above) solves your problem?

I have written an LTP test case to cover the fix - inotify08
and I can confirm that the test fails on Ubuntu 18.04, but the test does not
result in a hang, it results in events not being delivered, so not sure it is
related to the issue you are seeing. In any case, running inotofi over overlayfs
without this fix is not a good idea.

Mark,

Could you please re-post the backport patch per Greg's request.

Thanks,
Amir.