Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755072Ab3JCS4e (ORCPT ); Thu, 3 Oct 2013 14:56:34 -0400 Received: from zeniv.linux.org.uk ([195.92.253.2]:43433 "EHLO ZenIV.linux.org.uk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754397Ab3JCS4c (ORCPT ); Thu, 3 Oct 2013 14:56:32 -0400 Date: Thu, 3 Oct 2013 19:56:30 +0100 From: Al Viro To: Dave Jones , Linux Kernel , ebiederm@xmission.com, Linus Torvalds Subject: Re: pipe/cred lockdep warning Message-ID: <20131003185630.GJ13318@ZenIV.linux.org.uk> References: <20131001145755.GA22729@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20131001145755.GA22729@redhat.com> User-Agent: Mutt/1.5.21 (2010-09-15) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1199 Lines: 30 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: [] proc_pid_attr_write+0xf5/0x140 > [ 2836.628624] > but task is already holding lock: > [ 2836.628664] (&pipe->mutex/1){+.+.+.}, at: [] pipe_lock+0x26/0x30 > [ 2836.628734] splice to /proc//attr/ [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//attr/ 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... -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/