linux-kernel - Re: possible deadlock in generic_file_write

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Message-ID: <20171107081143.GD3326@worktop>
Date:   Tue, 7 Nov 2017 09:11:43 +0100
From:   Peter Zijlstra <peterz@...radead.org>
To:     Byungchul Park <byungchul.park@....com>
Cc:     Dmitry Vyukov <dvyukov@...gle.com>,
        Al Viro <viro@...iv.linux.org.uk>, Jan Kara <jack@...e.cz>,
        syzbot 
        <bot+f99f3a0db9007f4f4e32db54229a240c4fe57c15@...kaller.appspotmail.com>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Johannes Weiner <hannes@...xchg.org>, jlayton@...hat.com,
        LKML <linux-kernel@...r.kernel.org>, linux-mm@...ck.org,
        npiggin@...il.com, rgoldwyn@...e.com, ross.zwisler@...ux.intel.com,
        syzkaller-bugs@...glegroups.com, Ingo Molnar <mingo@...hat.com>,
        kernel-team@....com
Subject: Re: possible deadlock in generic_file_write_iter

On Tue, Nov 07, 2017 at 09:54:42AM +0900, Byungchul Park wrote:
> > The best I could come up with is something like the below; its not
> > at all pretty and I could see people objecting; least of all myself for
> > the __complete() thing, but I ran out of creative naming juice.
> 
> Patches assigning a lock_class per gendisk were already applied in tip.
> I believe that solves this.
> 
>    e319e1fbd9d42420ab6eec0bfd75eb9ad7ca63b1
>    block, locking/lockdep: Assign a lock_class per gendisk used for
>    wait_for_completion()
> 
> I think the following proposal makes kernel too hacky.

Ah, I tough this was with those included...