Received-SPF: pass (google.com: best guess record for domain of linux-kernel-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) client-ip=209.132.180.67;
MIME-Version: 1.0
In-Reply-To: <20180417103344.GB8445@kroah.com>
References: <20180416132550.d25jtdntdvpy55l3@bender.morinfr.org>
 <20180416144041.t2mt7ugzwqr56ka3@quack2.suse.cz> <KL1P15301MB0006B378757EC8F6B4D87BBBBFB00@KL1P15301MB0006.APCP153.PROD.OUTLOOK.COM>
 <20180417103344.GB8445@kroah.com>
From:   Amir Goldstein <amir73il@gmail.com>
Date:   Tue, 17 Apr 2018 14:48:35 +0300
Message-ID: <CAOQ4uxix615i5pVFURtfAH3OmgiYuy37WD7hM8tA=69OCv9B1A@mail.gmail.com>
Subject: Re: kernel panics with 4.14.X versions
To:     Greg KH <greg@kroah.com>
Cc:     Dexuan Cui <decui@microsoft.com>, Jan Kara <jack@suse.cz>,
        Guillaume Morin <guillaume@morinfr.org>,
        Haiyang Zhang <haiyangz@microsoft.com>,
        Pavlos Parissis <pavlos.parissis@gmail.com>,
        "stable@vger.kernel.org" <stable@vger.kernel.org>,
        "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>
Content-Type: text/plain; charset="UTF-8"
Sender: linux-kernel-owner@vger.kernel.org
Precedence: bulk

On Tue, Apr 17, 2018 at 1:33 PM, Greg KH <greg@kroah.com> wrote:
> 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 / 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?
>

Looking at the changes between 4.14 and 4.15, that are not in 4.14.32,
the only viable suspects are:
9cf90cef362d fsnotify: Protect bail out path of fsnotify_add_mark_locked()
properly
3427ce715541 fsnotify: clean up fsnotify()

Both don't claim to fix a known issue.
Both look like they could be applied cleanly to 4.14.y.

Thanks,
Amir.