From: Al Viro <viro@ZenIV.linux.org.uk>
To: Dave Jones <davej@redhat.com>,
Linux Kernel <linux-kernel@vger.kernel.org>,
ebiederm@xmission.com,
Linus Torvalds <torvalds@linux-foundation.org>
Subject: Re: pipe/cred lockdep warning
Date: Thu, 3 Oct 2013 19:56:30 +0100 [thread overview]
Message-ID: <20131003185630.GJ13318@ZenIV.linux.org.uk> (raw)
In-Reply-To: <20131001145755.GA22729@redhat.com>
On Tue, Oct 01, 2013 at 10:57:55AM -0400, Dave Jones wrote:
> I seem to recall hitting this quite a while ago. Does it look familiar ?
> Either it didn't get fixed, or it's back..
> [ 2836.628506] trinity-child0/30759 is trying to acquire lock:
> [ 2836.628544] (&sig->cred_guard_mutex){+.+.+.}, at: [<ffffffff81239045>] proc_pid_attr_write+0xf5/0x140
> [ 2836.628624]
> but task is already holding lock:
> [ 2836.628664] (&pipe->mutex/1){+.+.+.}, at: [<ffffffff811ccf66>] pipe_lock+0x26/0x30
> [ 2836.628734]
splice to /proc/<pid>/attr/<something> [cred_guard shite under pipe->mutex]
vs.
splice from XFS [pipe->mutex under exclusive iolock]
vs.
read from XFS in execve() [shared iolock under cred_guard]
Note, BTW, that splice to /proc/<pid>/attr/<something> is broken.
proc_pid_attr_write() is *not* supposed to allow partial writes at all.
Frankly, I'd consider adding a ->splice_write() instance that would
simply return -EINVAL there...
next prev parent reply other threads:[~2013-10-03 18:56 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-10-01 14:57 pipe/cred lockdep warning Dave Jones
2013-10-03 18:56 ` Al Viro [this message]
2013-10-04 23:27 ` Linus Torvalds
2013-10-05 0:46 ` Al Viro
[not found] ` <CA+55aFzrJ4JpfXxGA6LTd_fe-dEjTHhPEY2bkWEJJ=AF-FfT4Q@mail.gmail.com>
2013-10-05 1:42 ` Al Viro
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