Re: migratepage failures on reiserfs

[Badari Pulavarty <pbadari@us.ibm.com>]

On Thu, 2007-11-01 at 11:51 -0400, Chris Mason wrote:
> On Thu, 01 Nov 2007 08:38:57 -0800
> Badari Pulavarty <pbadari@us.ibm.com> wrote:
> 
> > On Wed, 2007-10-31 at 13:40 -0400, Chris Mason wrote:
> > > On Wed, 31 Oct 2007 08:14:21 -0800
> > > Badari Pulavarty <pbadari@us.ibm.com> wrote:
> > > > 
> > > > I tried data=writeback mode and it didn't help :(
> > > 
> > > Ouch, so much for the easy way out.
> > > 
> > > > 
> > > > unable to release the page 262070
> > > > bh c0000000211b9408 flags 110029 count 1 private 0
> > > > unable to release the page 262098
> > > > bh c000000020ec9198 flags 110029 count 1 private 0
> > > > memory offlining 3f000 to 40000 failed
> > > > 
> > > 
> > > The only other special thing reiserfs does with the page cache is
> > > file tails.  I don't suppose all of these pages are index zero in
> > > files smaller than 4k?
> > 
> > Ahhhhhhhhhhhhh !! I am so blind :(
> > 
> > I have been suspecting reiserfs all along, since its executing
> > fallback_migrate_page(). Actually, these buffer heads are
> > backing blockdev. I guess these are metadata buffers :( 
> > I am not sure we can do much with these..
> 
> Hmpf, my first reply had a paragraph about the block device inode
> pages, I noticed the phrase file data pages and deleted it ;)
> 
> But, for the metadata buffers there's not much we can do.  They are
> included in a bunch of different lists and the patch would
> be non-trivial.

Unfortunately, these buffer pages are spread all around making
those sections of memory non-removable. Of course, one can use
ZONE_MOVABLE to make sure to guarantee the remove. But I am
hoping we could easily group all these allocations and minimize
spreading them around. Mel ?

Thanks,
Badari

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