From: Amir Goldstein <amir73il@gmail.com>
To: Dmitry Vyukov <dvyukov@google.com>
Cc: syzbot+695726bc473f9c36a4b6@syzkaller.appspotmail.com,
Miklos Szeredi <miklos@szeredi.hu>,
linux-fsdevel <linux-fsdevel@vger.kernel.org>,
linux-kernel <linux-kernel@vger.kernel.org>,
overlayfs <linux-unionfs@vger.kernel.org>,
syzkaller-bugs@googlegroups.com
Subject: Re: possible deadlock in ovl_write_iter
Date: Tue, 27 Nov 2018 18:13:03 +0200 [thread overview]
Message-ID: <CAOQ4uxhjFjeQ6m6c84Hv9V73brMKEOFNsg3Q1Kjb3resSdDjyA@mail.gmail.com> (raw)
In-Reply-To: <CACT4Y+bkAcCcy3p-iKe4jAzA=ZOk-WmbZrD0yOG96sjA7o-cXA@mail.gmail.com>
> > This looks like a false positive because lockdep is not aware of
> > s_stack_depth of the file (fs) associated with the pipe.
>
> There must be some annotation to tell lockdep about this.
>
It's a long story that can be summed up as "not simple":
https://lkml.org/lkml/2017/9/21/63
Overlayfs annotates inode mutex in lockdep friendly manner.
This is why you see:
(&ovl_i_mutex_key[depth]){+.+.}, at: inode_lock
But this does not extend to other locks that may be associated
with filesystem or blockdev objects (e.g. pipe_lock()) and does
not cover the case of stacked blockdev (e.g. loop).
Thanks,
Amir.
prev parent reply other threads:[~2018-11-28 3:11 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <00000000000074e10d0576cc48f1@google.com>
[not found] ` <CAOQ4uxik7QbQVBQbaPWCxPG90HuJK=T0yckoyfe5NjLHhg898Q@mail.gmail.com>
2018-09-27 3:51 ` possible deadlock in ovl_write_iter Amir Goldstein
2018-11-27 7:06 ` syzbot
2018-11-27 7:44 ` Amir Goldstein
2018-11-27 14:12 ` Dmitry Vyukov
2018-11-27 15:07 ` Amir Goldstein
2018-11-27 15:48 ` Dmitry Vyukov
2018-11-27 16:13 ` Amir Goldstein [this message]
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