Re: grow_dev_page's __GFP_MOVABLE

[Mel Gorman <mel@csn.ul.ie>]

On (13/03/08 16:50), Badari Pulavarty didst pronounce:
> > > <SNIP>
> > > page_owner shows:
> > > 
> > > Page allocated via order 0, mask 0x120050
> > > PFN 30625 Block 7 type 2          Flags      L
> > 
> > This page is indicated as being on the LRU so it should have been possible
> > to reclaim. Is memory hot-remove making any effort to reclaim this page or
> > is it depending only on page migration?
> 
> offline_pages() finds all the pages on LRU and tries to migrate them by
> calling unmap_and_move(). I don't see any explicit attempt to reclaim.
> It tries to migrate the page (move_to_new_page()), but what I have seen
> in the past is that these pages have buffer heads attached to them. 
> So, migrate_page_move_mapping() fails to release the page. (BTW,
> I narrowed this in Oct 2007 and forgot most of the details). I can
> take a closer look again. Can we reclaim these pages easily ?
> 

They should be, or huge page allocations using lumpy reclaim would also
be failing all the time.

> > 
> > > [0xc0000000000c511c] .alloc_pages_current+208
> > > [0xc0000000001049d8] .__find_get_block_slow+88
> > > [0xc0000000004f0bbc] .__wait_on_bit+232
> > > [0xc0000000000994ec] .__page_cache_alloc+24
> > > [0xc000000000104fd8] .__find_get_block+272
> > > [0xc00000000009a124] .find_or_create_page+76
> > > [0xc0000000001063fc] .unlock_buffer+48
> > > [0xc000000000105280] .__getblk+312
> > > 
> 
> Thanks,
> Badari
> 

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

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