Re: Linux kernel 2.6.34.7 lvm error

[Zdenek Kabelac]

Dne 4.10.2010 10:46, Zdenek Kabelac napsal(a):
> Dne 3.10.2010 11:56, chich21@xxxxxxxx napsal(a):
>> With Linux kernel 2.6.34.7 from www.kernel.org the following error occurs.
>>
>> Issuing this command produces error.
>>
>> vgchange -ay
>>
>> outputs:
>> Internal error: Maps lock 14317216 < unlock 14321312
>>
>> vgchange is part of lvm-tools.
>>
>> This doesn't happen with kernel 2.6.34 or 2.6.34.1 from www.kernel.org.
>>
>> Is there a patch for 2.6.34.x series coming for this error. As there is one
>> for 2.6.35.x series.
>>
>> Please CC email me related posts.
> 
> 
> Bug is related to stack guard fix - kernel 2.6.36-rc4 has this problem fixed.
> Bug is present in 2.6.36-rc3 - so something between them fixes the problem.
> 
> It looks like the [stack] mapping loses 1 page after each mlock/munlock cycle.
> I'm probably going to play bisect game to find out missing fix.
> 
> https://bugzilla.redhat.com/show_bug.cgi?id=638525
> 

So - after bisecting - it seems that commit:

39aa3cb3e8250db9188a6f1e3fb62ffa1a717678
"mm: Move vma_stack_continue into mm.h"  by Stefan

had a nice 'bug-fixing' side effect which have not been mentioned in its
description - it fixes misbehaving of mlock/munlock [stack] mapping size.

So I assume this commit should be backported to stable kernels as well when
there is stack-guard patch already added.

Cc: stable@

Zdenek
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