From owner-freebsd-current Thu Jul 11 5:22:45 2002 Delivered-To: freebsd-current@freebsd.org Received: from mx1.FreeBSD.org (mx1.FreeBSD.org [216.136.204.125]) by hub.freebsd.org (Postfix) with ESMTP id 5A41D37B400 for ; Thu, 11 Jul 2002 05:22:43 -0700 (PDT) Received: from gw.catspoiler.org (217-ip-163.nccn.net [209.79.217.163]) by mx1.FreeBSD.org (Postfix) with ESMTP id E978343E09 for ; Thu, 11 Jul 2002 05:22:42 -0700 (PDT) (envelope-from dl-freebsd@catspoiler.org) Received: from mousie.catspoiler.org (mousie.catspoiler.org [192.168.101.2]) by gw.catspoiler.org (8.12.5/8.12.5) with ESMTP id g6BCMawr010506 for ; Thu, 11 Jul 2002 05:22:40 -0700 (PDT) (envelope-from dl-freebsd@catspoiler.org) Message-Id: <200207111222.g6BCMawr010506@gw.catspoiler.org> Date: Thu, 11 Jul 2002 05:22:36 -0700 (PDT) From: Don Lewis Subject: Re: "pipe mutex" vs. "sigio lock" lock order reversal To: current@FreeBSD.ORG In-Reply-To: <200207072343.g67Nhs0M024152@gw.catspoiler.org> MIME-Version: 1.0 Content-Type: TEXT/plain; charset=us-ascii Sender: owner-freebsd-current@FreeBSD.ORG Precedence: bulk List-ID: List-Archive: (Web Archive) List-Help: (List Instructions) List-Subscribe: List-Unsubscribe: X-Loop: FreeBSD.ORG On 7 Jul, Don Lewis wrote: > This error showed up in my logs this morning while I was building some > ports on a uni-processor box. I'm running a version of -current from > July 7 about 1 AM PDT. > > Jul 7 07:47:09 scratch kernel: lock order reversal > Jul 7 07:47:09 scratch kernel: 1st 0xcabf7980 pipe mutex (pipe mutex) @ /usr/src/sys/kern/sys_pipe.c:451 > Jul 7 07:47:09 scratch kernel: 2nd 0xc0474300 sigio lock (sigio lock) @ /usr/src/sys/kern/kern_sig.c:2113> I figured out part of the problem. The call stack is: pgsigio() pipe_read() dofileread() read() This was a bit tricky to find because the call to pgsigio() is hidden in pipeselwakeup(), which is an inline function called by pipe_read(). I don't see a good way to fix this. I also don't yet know why witness thinks it has seen the locks asserted in the opposite order. To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-current" in the body of the message