> > On Fri, Aug 20, 2010 at 04:14:00PM +0200, Michal Hocko wrote:
> > > Hi,
> > > what do you think about the patch below?
> > >
> > > >From b983695b92b5be58f31c719fada1d3245f7b6768 Mon Sep 17 00:00:00 2001
> > > From: Michal Hocko <mhocko@suse.cz>
> > > Date: Fri, 20 Aug 2010 15:39:16 +0200
> > > Subject: [PATCH] Make is_mem_section_removable more conformable with offlining code
> > >
> > > Currently is_mem_section_removable checks whether each pageblock from
> > > the given pfn range is of MIGRATE_MOVABLE type or if it is free. If both
> > > are false then the range is considered non removable.
> > >
> > > On the other hand, offlining code (more specifically
> > > set_migratetype_isolate) doesn't care whether a page is free and instead
> > > it just checks the migrate type of the page and whether the page's zone
> > > is movable.
> > >
> > > This can lead into a situation when a node is marked as removable even
> > > though all pages are neither MIGRATE_MOVABLE nor the zone is
> > > ZONE_MOVABLE.
> > >
> > > Also we can mark a node as not removable just because a pageblock is
> > > MIGRATE_RESERVE and not free (and this situation is much more probable).
> > > ---
> > > mm/memory_hotplug.c | 6 +++---
> > > 1 files changed, 3 insertions(+), 3 deletions(-)
> > >
> > > diff --git a/mm/memory_hotplug.c b/mm/memory_hotplug.c
> > > index a4cfcdc..da20568 100644
> > > --- a/mm/memory_hotplug.c
> > > +++ b/mm/memory_hotplug.c
> > > @@ -611,10 +611,10 @@ int is_mem_section_removable(unsigned long start_pfn, unsigned long nr_pages)
> > > type = get_pageblock_migratetype(page);
> > >
> > > /*
> > > - * A pageblock containing MOVABLE or free pages is considered
> > > - * removable
> > > + * A pageblock containing MOVABLE or page from movable
> > > + * zone are considered removable
> > > */
> > > - if (type != MIGRATE_MOVABLE && !pageblock_free(page))
> > > + if (type != MIGRATE_MOVABLE && zone_idx(page) != ZONE_MOVABLE)
> > > return 0;
> > >
> > > /*
> > > --
> > > 1.7.1
> > >
> > >
> > > --
> > > Michal Hocko
> > > L3 team
> > > SUSE LINUX s.r.o.
> > > Lihovarska 1060/12
> > > 190 00 Praha 9
> > > Czech Republic
> > >
> > > --
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> > > the body to
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> > > see:
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>
> --
> Michal Hocko
> L3 team
> SUSE LINUX s.r.o.
> Lihovarska 1060/12
> 190 00 Praha 9
> Czech Republic
