linux-kernel - Re: INFO: task hung in fsnotify_connector_destroy

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Message-ID: <CAOQ4uxhmFsvy6y6NgcFPs4NF1Lg7J0h2VoWgiL8WfXdDz+Z0FQ@mail.gmail.com>
Date:   Sun, 16 Sep 2018 02:05:11 +0300
From:   Amir Goldstein <amir73il@...il.com>
To:     penguin-kernel@...ove.sakura.ne.jp
Cc:     syzbot+6fb572170402d311dd39@...kaller.appspotmail.com,
        Jan Kara <jack@...e.cz>, syzkaller-bugs@...glegroups.com,
        linux-fsdevel <linux-fsdevel@...r.kernel.org>,
        linux-kernel <linux-kernel@...r.kernel.org>,
        Jiri Kosina <jikos@...nel.org>
Subject: Re: INFO: task hung in fsnotify_connector_destroy_workfn (2)

On Sat, Sep 15, 2018 at 8:26 PM Tetsuo Handa
<penguin-kernel@...ove.sakura.ne.jp> wrote:
>
> On 2018/09/15 11:33, syzbot wrote:
> > Hello,
> >
> > syzbot found the following crash on:
> >
> > HEAD commit:    11da3a7f84f1 Linux 4.19-rc3
> > git tree:       upstream
> > console output: https://syzkaller.appspot.com/x/log.txt?x=141ffbca400000
> > kernel config:  https://syzkaller.appspot.com/x/.config?x=9917ff4b798e1a1e
> > dashboard link: https://syzkaller.appspot.com/bug?extid=6fb572170402d311dd39
> > compiler:       gcc (GCC) 8.0.1 20180413 (experimental)
> > syz repro:      https://syzkaller.appspot.com/x/repro.syz?x=136a60ae400000
> >
> > IMPORTANT: if you fix the bug, please add the following tag to the commit:
> > Reported-by: syzbot+6fb572170402d311dd39@...kaller.appspotmail.com
> >
>
> Since it kept printk()ing for at least 93 seconds, it might have kept for 150 seconds.
>
> [  174.614333] hid-generic 0000:0000:0000.0003: unknown main item tag 0x0
> [  268.196102] INFO: task kworker/u4:1:23 blocked for more than 140 seconds.
>
> Since the reproducer is simple, this might be lockup due to continuous printk().
> If syzbot can reliably reproduce this problem using the reproducer, try
> ratelimiting printk().

Right.. and I was able to reproduce after setting CONFIG_HID_GENERIC=y
but unless I am missing something, the core problem doesn't seem related to
fsnotify and $SUBJECT, so CCing HID maintainer.

Thanks,
Amir.