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From:   Aleksandr Nogikh <nogikh@google.com>
Date:   Mon, 1 May 2023 11:18:28 +0200
Message-ID: <CANp29Y7dG3Z11Bt99rS0y8epdXfaKk+HJfXt=ePbm29vYF88Gg@mail.gmail.com>
Subject: Re: [syzbot] [sysv?] [vfs?] WARNING in invalidate_bh_lru
To:     "Theodore Ts'o" <tytso@mit.edu>
Cc:     syzbot <syzbot+9743a41f74f00e50fc77@syzkaller.appspotmail.com>,
        hch@infradead.org, linux-fsdevel@vger.kernel.org,
        linux-kernel@vger.kernel.org, syzkaller-bugs@googlegroups.com,
        viro@zeniv.linux.org.uk
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Hi Ted,

On Sun, Apr 30, 2023 at 8:40=E2=80=AFAM Theodore Ts'o <tytso@mit.edu> wrote=
:
>
> On Wed, Dec 21, 2022 at 06:57:38PM -0800, syzbot wrote:
> > Hello,
> >
> > syzbot found the following issue on:
> >
> > HEAD commit:    a5541c0811a0 Merge branch 'for-next/core' into for-kern=
elci
> > git tree:       git://git.kernel.org/pub/scm/linux/kernel/git/arm64/lin=
ux.git for-kernelci
> > console output: https://syzkaller.appspot.com/x/log.txt?x=3D1560b830480=
000
> > kernel config:  https://syzkaller.appspot.com/x/.config?x=3Dcbd4e584773=
e9397
> > dashboard link: https://syzkaller.appspot.com/bug?extid=3D9743a41f74f00=
e50fc77
> > compiler:       Debian clang version 13.0.1-++20220126092033+75e33f71c2=
da-1~exp1~20220126212112.63, GNU ld (GNU Binutils for Debian) 2.35.2
> > userspace arch: arm64
> > syz repro:      https://syzkaller.appspot.com/x/repro.syz?x=3D15e320b38=
80000
> > C reproducer:   https://syzkaller.appspot.com/x/repro.c?x=3D147c0577880=
000
>
> #syz set subsystems: sysv, udf
>
> There are two reproducers, one that mounts a sysv file system, and the
> other which mounts a udf file system.  There is no mention of ext4 in
> the stack trace, and yet syzbot has assigned this to the ext4
> subsystem for some unknown reason.

In this particular case, there were two ext4-related crashes as well:

https://syzkaller.appspot.com/text?tag=3DCrashReport&x=3D14c7dd1b480000
https://syzkaller.appspot.com/text?tag=3DCrashReport&x=3D1153a07f480000

I think syzbot picked a too generic frame as a bug title and it just
got confused by crashes belonging to different filesystems.
Maybe we need to display subsystems for individual crashes as well, so
that it's easier for a human to understand what's going on..

--
Aleksandr


>
>                                         - Ted
>
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