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Date: Mon, 04 Oct 2010 10:46:26 +0200
From: Zdenek Kabelac <zkabelac@redhat.com>
Organization: Red Hat
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To: chich21@mail.com
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Subject: Re: Linux kernel 2.6.34.7 lvm error
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Dne 3.10.2010 11:56, chich21@mail.com 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

Meanwhile lvm tools were also updated to read whole mapping table before
locking pages to avoid reading some mapping lines twice.

Zdenek.