From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S934477Ab1ETPzO (ORCPT ); Fri, 20 May 2011 11:55:14 -0400 Received: from mga11.intel.com ([192.55.52.93]:18972 "EHLO mga11.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S933861Ab1ETPzM (ORCPT ); Fri, 20 May 2011 11:55:12 -0400 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="4.65,243,1304319600"; d="scan'208";a="4589634" Message-ID: <4DD68EDF.4030301@linux.intel.com> Date: Fri, 20 May 2011 08:55:11 -0700 From: Darren Hart User-Agent: Mozilla/5.0 (X11; U; Linux x86_64; en-US; rv:1.9.2.17) Gecko/20110424 Lightning/1.0b2 Thunderbird/3.1.10 MIME-Version: 1.0 To: richard -rw- weinberger CC: =?ISO-8859-1?Q?Toralf_F=F6rster?= , Steven Rostedt , LKML , user-mode-linux-devel@lists.sourceforge.net Subject: Re: kernel 2.6.39 (user mode linux) crashes (2.6.38 works fine) References: <201105191526.31904.toralf.foerster@gmx.de> <201105192218.18261.toralf.foerster@gmx.de> <20110519204342.GA10792@home.goodmis.org> <201105200937.15322.toralf.foerster@gmx.de> In-Reply-To: Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 05/20/2011 12:56 AM, richard -rw- weinberger wrote: > 2011/5/20 Toralf Förster : >> ... >> Kernel panic - not syncing: Kernel mode fault at addr 0x0, ip 0x80a9f6b > > Looks like a NULL-pointer bug. > What code is at address 80a9f6b? > Use "objdump -d -S | less" to find it. > Please note, kernel binary and log message have to match! > >> The file /var/log/messages of the UML says : >> >> 2011-05-20T09:33:03.455+02:00 n22_uml kernel: ------------[ cut here ]------------ >> 2011-05-20T09:33:03.455+02:00 n22_uml kernel: WARNING: at kernel/futex.c:789 wake_futex+0x28/0x60() > > Is this really 2.6.39? > Line 789 contains no WARN*(). > http://lxr.linux.no/#linux+v2.6.39/kernel/futex.c#L789 > I suspect Toralf is hitting the WARN_ON in __unqueue_futex: if (WARN_ON(!q->lock_ptr || !spin_is_locked(q->lock_ptr) || plist_node_empty(&q->list))) Toralf, can you instrument that let us know which of conditions is triggering the WARN_ON? Something like the following should be adequate to get you the line number. I suspect it is plist_node_empty give the git bisect results you reported. diff --git a/kernel/futex.c b/kernel/futex.c index abd5324..7f31bca 100644 --- a/kernel/futex.c +++ b/kernel/futex.c @@ -782,8 +782,11 @@ static void __unqueue_futex(struct futex_q *q) { struct futex_hash_bucket *hb; - if (WARN_ON(!q->lock_ptr || !spin_is_locked(q->lock_ptr) - || plist_node_empty(&q->list))) + if (WARN_ON(!q->lock_ptr)) + return; + if (!spin_is_locked(q->lock_ptr)) + return; + if (plist_node_empty(&q->list)) return; hb = container_of(q->lock_ptr, struct futex_hash_bucket, lock); -- Darren Hart Intel Open Source Technology Center Yocto Project - Linux Kernel From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Message-ID: <4DD68EDF.4030301@linux.intel.com> Date: Fri, 20 May 2011 08:55:11 -0700 From: Darren Hart MIME-Version: 1.0 References: <201105191526.31904.toralf.foerster@gmx.de> <201105192218.18261.toralf.foerster@gmx.de> <20110519204342.GA10792@home.goodmis.org> <201105200937.15322.toralf.foerster@gmx.de> In-Reply-To: Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: QUOTED-PRINTABLE Sender: linux-kernel-owner@vger.kernel.org Subject: Re: kernel 2.6.39 (user mode linux) crashes (2.6.38 works fine) To: richard -rw- weinberger Cc: =?ISO-8859-1?Q?Toralf_F=F6rster?= , Steven Rostedt , LKML , user-mode-linux-devel@lists.sourceforge.net List-ID: On 05/20/2011 12:56 AM, richard -rw- weinberger wrote: > 2011/5/20 Toralf F=F6rster : >> ... >> Kernel panic - not syncing: Kernel mode fault at addr 0x0, ip 0x80a9= f6b >=20 > Looks like a NULL-pointer bug. > What code is at address 80a9f6b? > Use "objdump -d -S | less" to find it. > Please note, kernel binary and log message have to match! >=20 >> The file /var/log/messages of the UML says : >> >> 2011-05-20T09:33:03.455+02:00 n22_uml kernel: ------------[ cut here= ]------------ >> 2011-05-20T09:33:03.455+02:00 n22_uml kernel: WARNING: at kernel/fut= ex.c:789 wake_futex+0x28/0x60() >=20 > Is this really 2.6.39? > Line 789 contains no WARN*(). > http://lxr.linux.no/#linux+v2.6.39/kernel/futex.c#L789 >=20 I suspect Toralf is hitting the WARN_ON in __unqueue_futex: if (WARN_ON(!q->lock_ptr || !spin_is_locked(q->lock_ptr) || plist_node_empty(&q->list))) Toralf, can you instrument that let us know which of conditions is triggering the WARN_ON? Something like the following should be adequate to get you the line number. I suspect it is plist_node_empty give the git bisect results you reported. diff --git a/kernel/futex.c b/kernel/futex.c index abd5324..7f31bca 100644 --- a/kernel/futex.c +++ b/kernel/futex.c @@ -782,8 +782,11 @@ static void __unqueue_futex(struct futex_q *q) { struct futex_hash_bucket *hb; - if (WARN_ON(!q->lock_ptr || !spin_is_locked(q->lock_ptr) - || plist_node_empty(&q->list))) + if (WARN_ON(!q->lock_ptr)) + return; + if (!spin_is_locked(q->lock_ptr)) + return; + if (plist_node_empty(&q->list)) return; hb =3D container_of(q->lock_ptr, struct futex_hash_bucket, lock); --=20 Darren Hart Intel Open Source Technology Center Yocto Project - Linux Kernel -- 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/