[dm-devel] Re: [linux-lvm] snapshot with 2.6.5 kernel

[Dave Olien]

Here's the patch I have come up with.  If you can give it a try, that'd
be good.

The Ooops I'm fixing should only occur on an SMP machine.
The dm-exception-store.c module contained code that believed only
one thread could be executing it at a time.  This is NOT true in 2.6
with the multi-threaded work queue implementation.

This patch adds a lock and a wait queue into the code.

Now, I'm running the system out of KVA.  I've got lots of free memory,
but it's all in HIGHMEM.  A Sysrq ,  "m" command displays

Free pages:    15804032kB (15804032kB HighMem)

Using a larger chunk size on your snapshot should help.  The default
chunksize is 4k, I think.  try specifying chunksize 512.  The snapshot should
accept chunksize 1024, but this produces an Oops.  I'll look into a patch
for THAT next.


On Tue, May 11, 2004 at 01:13:45PM -0700, Dave Olien wrote:
> 
> I'm running linux 2.6.6-rc2-udm1.  I also have a very repeatable
> oops running snapshot.  I'm working on a patch.  I'll post it
> in the next day or two to lmv-devel.
> 
> Dave Olien
> OSDL
> 
> On Tue, May 11, 2004 at 01:13:22PM +0200, Heinz Mauelshagen wrote:
> > On Sun, May 02, 2004 at 11:42:05PM -0700, Karen Shaeffer wrote:
> > > 
> > > Hello,
> > > 
> > > I am running a patched 2.6.5 kernel and using lvm2. Everything
> > > looks ok, but the snapshot may be having problems.

---- stuff deleted ---

> > > 
> > You should be able to create a snapshot fine in ythat situation, even though
> > the creation will happen slow under load.
> > 
> > Can you repeat the case ?
> > Do you have an oops ? If so, please provide the ksymoops output
> > for further analysis of the problem.
> > 
> > > 
> > > Thanks,
> > > Karen
> > > -- 
> > >  Karen Shaeffer
> > >  Neuralscape, Palo Alto, Ca. 94306
> > >  shaeffer at neuralscape.com  http://www.neuralscape.com
> > > _______________________________________________
> > > linux-lvm mailing list
> > > linux-lvm at redhat.com
> > > https://www.redhat.com/mailman/listinfo/linux-lvm
> > > read the LVM HOW-TO at http://tldp.org/HOWTO/LVM-HOWTO/
> > 
> > -- 
> > 
> > Regards,
> > Heinz    -- The LVM Guy --
> > 
> > *** Software bugs are stupid.
> >     Nevertheless it needs not so stupid people to solve them ***
> > 
> > =-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-
> > 
> > Heinz Mauelshagen                                 Red Hat GmbH
> > Consulting Development Engineer                   Am Sonnenhang 11
> >                                                   56242 Marienrachdorf
> >                                                   Germany
> > Mauelshagen at RedHat.com                            +49 2626 141200
> >                                                        FAX 924446
> > =-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-
> > _______________________________________________
> > linux-lvm mailing list
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> > https://www.redhat.com/mailman/listinfo/linux-lvm
> > read the LVM HOW-TO at http://tldp.org/HOWTO/LVM-HOWTO/