From: Al Viro <viro@ZenIV.linux.org.uk>
To: Jan Kara <jack@suse.cz>
Cc: Dmitry Vyukov <dvyukov@google.com>,
syzbot
<bot+f99f3a0db9007f4f4e32db54229a240c4fe57c15@syzkaller.appspotmail.com>,
Andrew Morton <akpm@linux-foundation.org>,
Johannes Weiner <hannes@cmpxchg.org>,
jlayton@redhat.com, LKML <linux-kernel@vger.kernel.org>,
linux-mm@kvack.org, npiggin@gmail.com, rgoldwyn@suse.com,
ross.zwisler@linux.intel.com, syzkaller-bugs@googlegroups.com
Subject: Re: possible deadlock in generic_file_write_iter
Date: Mon, 6 Nov 2017 13:33:04 +0000 [thread overview]
Message-ID: <20171106133304.GS21978@ZenIV.linux.org.uk> (raw)
In-Reply-To: <20171106131544.GB4359@quack2.suse.cz>
On Mon, Nov 06, 2017 at 02:15:44PM +0100, Jan Kara wrote:
> > Should we annotate these inodes with different lock types? Or use
> > nesting annotations?
>
> Well, you'd need to have a completely separate set of locking classes for
> each filesystem to avoid false positives like these. And that would
> increase number of classes lockdep has to handle significantly. So I'm not
> sure it's really worth it...
Especially when you consider that backing file might be on a filesystem
that lives on another loop device. *All* per-{device,fs} locks involved
would need classes split that way...
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WARNING: multiple messages have this Message-ID (diff)
From: Al Viro <viro@ZenIV.linux.org.uk>
To: Jan Kara <jack@suse.cz>
Cc: Dmitry Vyukov <dvyukov@google.com>,
syzbot
<bot+f99f3a0db9007f4f4e32db54229a240c4fe57c15@syzkaller.appspotmail.com>,
Andrew Morton <akpm@linux-foundation.org>,
Johannes Weiner <hannes@cmpxchg.org>,
jlayton@redhat.com, LKML <linux-kernel@vger.kernel.org>,
linux-mm@kvack.org, npiggin@gmail.com, rgoldwyn@suse.com,
ross.zwisler@linux.intel.com, syzkaller-bugs@googlegroups.com
Subject: Re: possible deadlock in generic_file_write_iter
Date: Mon, 6 Nov 2017 13:33:04 +0000 [thread overview]
Message-ID: <20171106133304.GS21978@ZenIV.linux.org.uk> (raw)
In-Reply-To: <20171106131544.GB4359@quack2.suse.cz>
On Mon, Nov 06, 2017 at 02:15:44PM +0100, Jan Kara wrote:
> > Should we annotate these inodes with different lock types? Or use
> > nesting annotations?
>
> Well, you'd need to have a completely separate set of locking classes for
> each filesystem to avoid false positives like these. And that would
> increase number of classes lockdep has to handle significantly. So I'm not
> sure it's really worth it...
Especially when you consider that backing file might be on a filesystem
that lives on another loop device. *All* per-{device,fs} locks involved
would need classes split that way...
next prev parent reply other threads:[~2017-11-06 13:33 UTC|newest]
Thread overview: 31+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-11-05 10:25 possible deadlock in generic_file_write_iter syzbot
2017-11-05 10:39 ` Dmitry Vyukov
2017-11-05 10:39 ` Dmitry Vyukov
2017-11-06 3:29 ` Al Viro
2017-11-06 3:29 ` Al Viro
2017-11-06 6:32 ` Dmitry Vyukov
2017-11-06 6:32 ` Dmitry Vyukov
2017-11-06 13:15 ` Jan Kara
2017-11-06 13:15 ` Jan Kara
2017-11-06 13:33 ` Al Viro [this message]
2017-11-06 13:33 ` Al Viro
2017-11-06 13:35 ` Dmitry Vyukov
2017-11-06 13:35 ` Dmitry Vyukov
2017-11-06 16:01 ` Peter Zijlstra
2017-11-06 16:01 ` Peter Zijlstra
2017-11-06 17:36 ` Christoph Hellwig
2017-11-06 17:36 ` Christoph Hellwig
2017-11-06 23:45 ` Matthew Wilcox
2017-11-06 23:45 ` Matthew Wilcox
2017-11-07 0:54 ` Byungchul Park
2017-11-07 0:54 ` Byungchul Park
2017-11-07 8:11 ` Peter Zijlstra
2017-11-07 8:11 ` Peter Zijlstra
2017-11-07 8:18 ` Dmitry Vyukov
2017-11-07 8:18 ` Dmitry Vyukov
2017-11-07 8:30 ` Byungchul Park
2017-11-07 8:30 ` Byungchul Park
2017-11-07 8:31 ` Dmitry Vyukov
2017-11-07 8:31 ` Dmitry Vyukov
2017-11-07 8:42 ` Byungchul Park
2017-11-07 8:42 ` Byungchul Park
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