Re: [patch] mm, compaction: avoid isolating pinned pages fix

From: Joonsoo Kim
Date: Mon Feb 03 2014 - 21:16:05 EST

On Mon, Feb 03, 2014 at 06:00:56PM -0800, David Rientjes wrote:
> On Tue, 4 Feb 2014, Joonsoo Kim wrote:
> > Okay. It can't fix your situation. Anyway, *normal* anon pages may be mapped
> > and have positive page_count(), so your code such as
> > '!page_mapping(page) && page_count(page)' makes compaction skip these *normal*
> > anon pages and this is incorrect behaviour.
> >
> So how does that work with migrate_page_move_mapping() which demands
> page_count(page) == 1 and the get_page_unless_zero() in
> __isolate_lru_page()?

Before doing migrate_page_move_mapping(), try_to_unmap() is called so that all
mapping is unmapped. Then, remained page_count() is 1 which is grabbed by
__isolate_lru_page(). Am I missing something?

To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at
Please read the FAQ at