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Bug 546554

Summary:	kernel: no clue to find what is happening when hitting a lockdep limit
Product:	Red Hat Enterprise Linux 5	Reporter:	Cong Wang <amwang>
Component:	kernel	Assignee:	Cong Wang <amwang>
Status:	CLOSED ERRATA	QA Contact:	Red Hat Kernel QE team <kernel-qe>
Severity:	low	Docs Contact:
Priority:	medium
Version:	5.6	CC:	amwang, eguan, kzhang, rkhan
Target Milestone:	rc
Target Release:	---
Hardware:	All
OS:	Linux
Whiteboard:
Fixed In Version:		Doc Type:	Bug Fix
Doc Text:		Story Points:	---
Clone Of:		Environment:
Last Closed:	2011-01-13 20:57:24 UTC	Type:	---
Regression:	---	Mount Type:	---
Documentation:	---	CRM:
Verified Versions:		Category:	---
oVirt Team:	---	RHEL 7.3 requirements from Atomic Host:
Cloudforms Team:	---	Target Upstream Version:
Embargoed:

Description Cong Wang 2009-12-11 07:46:49 UTC

Description of problem:
When we hit some lockdep limit, we only get messages like this one:

BUG: MAX_LOCKDEP_CHAINS too low!
turning off the locking correctness validator.

We can't see what was happening at that time.

How reproducible:
Always

Expected results:

Dump the stack and process name, pid etc..

Should get something like:

[   21.401387] BUG: MAX_LOCKDEP_ENTRIES too low!
[   21.402007] turning off the locking correctness validator.
[   21.402007] Pid: 1555, comm: S99local Not tainted 2.6.30-rc5-tip #2
[   21.402007] Call Trace:
[   21.402007]  [<ffffffff81069789>] add_lock_to_list+0x53/0xba
[   21.402007]  [<ffffffff810eb615>] ? lookup_mnt+0x19/0x53
[   21.402007]  [<ffffffff8106be14>] check_prev_add+0x14b/0x1c7
[   21.402007]  [<ffffffff8106c304>] validate_chain+0x474/0x52a
[   21.402007]  [<ffffffff8106c6fc>] __lock_acquire+0x342/0x3c7
[   21.402007]  [<ffffffff8106c842>] lock_acquire+0xc1/0xe5
[   21.402007]  [<ffffffff810eb615>] ? lookup_mnt+0x19/0x53
[   21.402007]  [<ffffffff8153aedc>] _spin_lock+0x31/0x66

Comment 1 Cong Wang 2009-12-11 07:48:31 UTC

Take this BZ as an example:
https://bugzilla.redhat.com/show_bug.cgi?id=545315

Comment 2 Cong Wang 2009-12-11 07:49:58 UTC

Upstream patch:
http://git.kernel.org/?p=linux/kernel/git/torvalds/linux-2.6.git;a=commitdiff;h=eedeeabd

Comment 5 RHEL Program Management 2010-01-07 21:50:45 UTC

This request was evaluated by Red Hat Product Management for inclusion in a Red
Hat Enterprise Linux maintenance release.  Product Management has requested
further review of this request by Red Hat Engineering, for potential
inclusion in a Red Hat Enterprise Linux Update release for currently deployed
products.  This request is not yet committed for inclusion in an Update
release.

Comment 7 RHEL Program Management 2010-05-20 12:45:19 UTC

This request was evaluated by Red Hat Product Management for inclusion in a Red
Hat Enterprise Linux maintenance release.  Product Management has requested
further review of this request by Red Hat Engineering, for potential
inclusion in a Red Hat Enterprise Linux Update release for currently deployed
products.  This request is not yet committed for inclusion in an Update
release.

Comment 9 Jarod Wilson 2010-05-25 21:10:54 UTC

in kernel-2.6.18-200.el5
You can download this test kernel from http://people.redhat.com/jwilson/el5

Detailed testing feedback is always welcomed.

Comment 11 Eryu Guan 2010-11-02 11:06:00 UTC

This patch is quite straight-forward, codereview and confirmed linux-2.6-misc-lockdep-dump-stack-when-hitting-a-limit.patch is included in 2.6.18-230.el5 kernel

Comment 13 errata-xmlrpc 2011-01-13 20:57:24 UTC

An advisory has been issued which should help the problem
described in this bug report. This report is therefore being
closed with a resolution of ERRATA. For more information
on therefore solution and/or where to find the updated files,
please follow the link below. You may reopen this bug report
if the solution does not work for you.

http://rhn.redhat.com/errata/RHSA-2011-0017.html