On (01/11/07 10:10), Badari Pulavarty didst pronounce:
quoted text
> 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 ?

The grow_dev_page() pages should be reclaimable even though migration
is not supported for those pages? They were marked movable as it was
useful for lumpy reclaim taking back pages for hugepage allocations and
the like. Would it make sense for memory unremove to attempt migration
first and reclaim second?

-- 
Mel Gorman
Part-time Phd Student                          Linux Technology Center
University of Limerick                         IBM Dublin Software Lab
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