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From:   Dmitry Vyukov <dvyukov@google.com>
Date:   Tue, 4 Sep 2018 10:28:52 +0200
Message-ID: <CACT4Y+YtQb3XmxGDn7Y3mkxj08a5iPbFPtpXiHzaY3H5UQZbyQ@mail.gmail.com>
Subject: Re: WARNING in up_write
To:     Matthew Wilcox <willy@infradead.org>
Cc:     "Theodore Y. Ts'o" <tytso@mit.edu>,
        syzbot <syzbot+dc5ab2babdf22ca091af@syzkaller.appspotmail.com>,
        linux-fsdevel <linux-fsdevel@vger.kernel.org>,
        LKML <linux-kernel@vger.kernel.org>,
        syzkaller-bugs <syzkaller-bugs@googlegroups.com>,
        Al Viro <viro@zeniv.linux.org.uk>
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On Thu, Apr 5, 2018 at 10:22 AM, Dmitry Vyukov <dvyukov@google.com> wrote:
> On Thu, Apr 5, 2018 at 5:24 AM, Matthew Wilcox <willy@infradead.org> wrote:
>> On Wed, Apr 04, 2018 at 11:22:00PM -0400, Theodore Y. Ts'o wrote:
>>> On Wed, Apr 04, 2018 at 12:35:04PM -0700, Matthew Wilcox wrote:
>>> > On Wed, Apr 04, 2018 at 09:24:05PM +0200, Dmitry Vyukov wrote:
>>> > > On Tue, Apr 3, 2018 at 4:01 AM, syzbot
>>> > > <syzbot+dc5ab2babdf22ca091af@syzkaller.appspotmail.com> wrote:
>>> > > > DEBUG_LOCKS_WARN_ON(sem->owner != get_current())
>>> > > > WARNING: CPU: 1 PID: 4441 at kernel/locking/rwsem.c:133 up_write+0x1cc/0x210
>>> > > > kernel/locking/rwsem.c:133
>>> > > > Kernel panic - not syncing: panic_on_warn set ...
>>> >
>>> > Message-Id: <1522852646-2196-1-git-send-email-longman@redhat.com>
>>> >
>>>
>>> We were way ahead of syzbot in this case.  :-)
>>
>> Not really ... syzbot caught it Monday evening ;-)
>>
>> Date: Mon, 02 Apr 2018 19:01:01 -0700
>> From: syzbot <syzbot+dc5ab2babdf22ca091af@syzkaller.appspotmail.com>
>> To: linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org,
>>         syzkaller-bugs@googlegroups.com, viro@zeniv.linux.org.uk
>> Subject: WARNING in up_write
>
> :)
>
> #syz fix: locking/rwsem: Add up_write_non_owner() for percpu_up_write()

The title was later changed to:

#syz fix: locking/rwsem: Add a new RWSEM_ANONYMOUSLY_OWNED flag