From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1758114AbYHUIKu (ORCPT ); Thu, 21 Aug 2008 04:10:50 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1755198AbYHUIKf (ORCPT ); Thu, 21 Aug 2008 04:10:35 -0400 Received: from py-out-1112.google.com ([64.233.166.176]:37198 "EHLO py-out-1112.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755576AbYHUIKc (ORCPT ); Thu, 21 Aug 2008 04:10:32 -0400 DomainKey-Signature: a=rsa-sha1; c=nofws; d=gmail.com; s=gamma; h=message-id:date:from:to:subject:cc:in-reply-to:mime-version :content-type:references; b=GJRPNm3Koql5P45T5enuxOOIbPNT+nPG9I7aa6YMmTJfOkb84FEkyps4but2sfyri9 lORQbNUWut+e1ciYesRGuX1/VYUuJLAAqNhkC1ENBxSRPnTOXordGA9uEHGHSK7DzXVG cnXT8JTvZNLYBVm+Ol0IaD2e/Yvyh9tj9FdX0= Message-ID: <19f34abd0808210110s4dd2ec12r6d3044e45a21d67@mail.gmail.com> Date: Thu, 21 Aug 2008 10:10:30 +0200 From: "Vegard Nossum" To: "jay kumar" Subject: Re: Bug: "bad unlock balance detected" 2.6.27-rc3-next-20080820 Cc: "David Howells" , linux-kernel@vger.kernel.org, linux-next@vger.kernel.org In-Reply-To: <6f31812b0808210004i63b3273ehf65ce9eb139256f0@mail.gmail.com> MIME-Version: 1.0 Content-Type: multipart/mixed; boundary="----=_Part_47168_6489128.1219306230795" References: <6f31812b0808210004i63b3273ehf65ce9eb139256f0@mail.gmail.com> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org ------=_Part_47168_6489128.1219306230795 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit Content-Disposition: inline On Thu, Aug 21, 2008 at 9:04 AM, jay kumar wrote: > While testing 2.6.27-rc3-next-20080820 , i observed this "BUG:bad > unlock balance detected" during boot time > > commit 765d4840cc9cca98c0cc4ff4764608780c3265f6 > Author: Stephen Rothwell > Date: Wed Aug 20 18:59:47 2008 +1000 > > > Bug info: > > [ 0.140173] ===================================== > [ 0.145977] [ BUG: bad unlock balance detected! ] > [ 0.145977] ------------------------------------- > [ 0.145977] khelper/12 is trying to release lock (&p->cred_exec_mutex) at: > [ 0.146977] [] mutex_unlock+0xd/0xf > [ 0.146977] but there are no more locks to release! > [ 0.146977] > [ 0.146977] other info that might help us debug this: > [ 0.146977] no locks held by khelper/12. > [ 0.146977] > [ 0.146977] stack backtrace: > [ 0.146977] Pid: 12, comm: khelper Not tainted 2.6.27-rc3-next-20080820 #13 > [ 0.146977] [] ? mutex_unlock+0xd/0xf > [ 0.146977] [] print_unlock_inbalance_bug+0xa5/0xb2 > [ 0.146977] [] ? mutex_unlock+0xd/0xf > [ 0.146977] [] lock_release+0x8f/0x186 > [ 0.146977] [] __mutex_unlock_slowpath+0x9b/0xed > [ 0.146977] [] mutex_unlock+0xd/0xf > [ 0.146977] [] free_bprm+0x24/0x39 > [ 0.146977] [] do_execve+0x1e5/0x1fb > [ 0.146977] [] sys_execve+0x2e/0x51 > [ 0.146977] [] syscall_call+0x7/0xb > [ 0.146977] [] ? kernel_execve+0x1c/0x21 > [ 0.146977] [] ? ____call_usermodehelper+0x0/0x129 > [ 0.146977] [] ? ____call_usermodehelper+0x11f/0x129 > [ 0.146977] [] ? ____call_usermodehelper+0x0/0x129 > [ 0.146977] [] ? kernel_thread_helper+0x7/0x10 > [ 0.146977] ======================= (config clipped) Hi, Thanks for the report. The error comes from commit d9a939fb80ef390b78b3c801f668bd1e35ebc970 Author: David Howells Date: Thu Aug 7 20:02:20 2008 +1000 CRED: Make execve() take advantage of copy-on-write credentials (Added to Cc. I guess it's also nice to Cc linux-next on errors in -next code.) I couldn't reproduce your original failure, but I've attempted to fix it by reordering the mutex unlock and bprm free and removing the extraneous unlock (see attached patch; it boots for me without errors). Vegard -- "The animistic metaphor of the bug that maliciously sneaked in while the programmer was not looking is intellectually dishonest as it disguises that the error is the programmer's own creation." -- E. W. 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