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
References: <CAJfpegtUAHPL9tsFB85ZqjAfy0xwz7ATRcCtLbzFBo8=WnCvLw@mail.gmail.com>
 <20200209080918.1562823-1-michael+lkml@stapelberg.ch>
In-Reply-To: <20200209080918.1562823-1-michael+lkml@stapelberg.ch>
From:   Miklos Szeredi <miklos@szeredi.hu>
Date:   Tue, 11 Feb 2020 11:55:46 +0100
Message-ID: <CAJfpegv4iL=bW3TXP3F9w1z6-LUox8KiBmw7UBcWE-0jiK0YsA@mail.gmail.com>
Subject: Re: Still a pretty bad time on 5.4.6 with fuse_request_end.
To:     michael+lkml@stapelberg.ch
Cc:     fuse-devel <fuse-devel@lists.sourceforge.net>,
        Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        Kyle Sanderson <kyle.leet@gmail.com>,
        linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org
Content-Type: text/plain; charset="UTF-8"
Content-Transfer-Encoding: quoted-printable
Sender: linux-kernel-owner@vger.kernel.org
Precedence: bulk

On Sun, Feb 9, 2020 at 9:09 AM <michael+lkml@stapelberg.ch> wrote:
>
> From: Michael Stapelberg <michael+lkml@stapelberg.ch>
>
> Hey,
>
> I recently ran into this, too. The symptom for me is that processes using=
 the
> affected FUSE file system hang indefinitely, sync(2) system calls hang
> indefinitely, and even triggering an abort via echo 1 >
> /sys/fs/fuse/connections/*/abort does not get the file system unstuck (th=
ere is
> always 1 request still pending). Only removing power will get the machine
> unstuck.
>
> I=E2=80=99m triggering this when building packages for https://distr1.org=
/, which uses a
> FUSE daemon (written in Go using the jacobsa/fuse package) to provide pac=
kage
> contents.
>
> I bisected the issue to commit
> https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit=
/?id=3D2b319d1f6f92a4ced9897678113d176ee16ae85d
>
> With that commit, I run into a kernel oops within =E2=89=881 minute after=
 starting my
> batch build. With the commit before, I can batch build for many minutes w=
ithout
> issues.

Pretty weird.   I'm not seeing how this could change behavior, as the
args->end value is not changed after being initialized, and so moving
the test later should not make a difference.

Could you print out the complete contents of req->args?

Thanks,
Miklos