Bug 13126

Summary: BUG: MAX_LOCKDEP_ENTRIES too low! when mounting rootfs
Product: Other Reporter: Rafael J. Wysocki (rjw)
Component: OtherAssignee: other_other
Status: CLOSED CODE_FIX    
Severity: normal CC: alan, bryce
Priority: P1    
Hardware: All   
OS: Linux   
Kernel Version: 2.6.30-rc6 Subsystem:
Regression: Yes Bisected commit-id:
Bug Depends on:    
Bug Blocks: 13070    
Attachments: lockdep.c patch to be a little more informative when things bail out

Description Rafael J. Wysocki 2009-04-17 00:12:47 UTC 
Subject    : 2.6.30-rc2: BUG: MAX_LOCKDEP_ENTRIES too low! when mounting rootfs
Submitter  : Alexander Beregalov <a.beregalov@gmail.com>
Date       : 2009-04-15 12:43
References : http://marc.info/?l=linux-kernel&m=123979949820538&w=4

This entry is being used for tracking a regression from 2.6.29.  Please don't
close it until the problem is fixed in the mainline.
Comment 1 Philip Copeland 2009-04-26 01:21:26 UTC 
Seen with 2.6.30-rc3 as well
...
 device-mapper: multipath: version 1.0.5 loaded
 BUG: MAX_LOCKDEP_ENTRIES too low!
 turning off the locking correctness validator.
...

kernel/lockdep_internals.h:#define MAX_LOCKDEP_ENTRIES  8192UL

Phil
=--=
Comment 2 Philip Copeland 2009-04-26 01:54:40 UTC 
even doubled to 16384UL it fell over,.. either something is eating locks or something extremely bad is happening

Phil
=--=
Comment 3 Philip Copeland 2009-04-26 23:28:23 UTC 
Actually after talking with a few folk it seems that the whole lockdep system requirements have expanded massively since 2.6.20ish and no one has been bothered to resize the arrays accordingly

Incidentally it would be nice to actually spit out the sizes used rather than just 'too low'


Phil
=--=
Comment 4 Philip Copeland 2009-04-26 23:33:05 UTC 
Created attachment 21128 [details]
lockdep.c patch to be a little more informative when things bail out

lockdep.c patch to be a little more informative when things bail out
'too low!' is extremely uninformative about what happened. esp as the values may change from kernel to kernel from what you might have expected
Comment 5 Rafael J. Wysocki 2009-05-13 10:52:27 UTC 
Notify-Also : Philip Copeland <bryce@zeniv.linux.org.uk>
Comment 6 Alan 2009-05-21 19:12:22 UTC 
Still present in rc6
Comment 7 Rafael J. Wysocki 2009-05-25 23:18:18 UTC 
On Monday 25 May 2009, Peter Zijlstra wrote:
> On Sun, 2009-05-24 at 21:11 +0200, Rafael J. Wysocki wrote:
> > This message has been generated automatically as a part of a report
> > of recent regressions.
> > 
> > The following bug entry is on the current list of known regressions
> > from 2.6.29.  Please verify if it still should be listed and let me know
> > (either way).
> > 
> > 
> > Bug-Entry   : http://bugzilla.kernel.org/show_bug.cgi?id=13126
> > Subject             : BUG: MAX_LOCKDEP_ENTRIES too low! when mounting
> rootfs
> > Submitter   : Alexander Beregalov <a.beregalov@gmail.com>
> > Date                : 2009-04-15 12:43 (40 days old)
> > References  : http://marc.info/?l=linux-kernel&m=123979949820538&w=4
> 
> -rc7 includes:
> 
> Ingo Molnar (1):
>       lockdep: increase MAX_LOCKDEP_ENTRIES and MAX_LOCKDEP_CHAINS
> 
> Which can be found with commit id: 
>    d80c19df5fcceb8c741e96f09f275c2da719efef