Messages in this thread | | | Subject | Re: [RFC PATCH 3/4] mm: add zbud flag to page flags | From | Krzysztof Kozlowski <> | Date | Thu, 08 Aug 2013 09:26:34 +0200 |
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Hi,
On wto, 2013-08-06 at 09:58 -0700, Dave Hansen wrote: > On 08/05/2013 11:42 PM, Krzysztof Kozlowski wrote: > > +#ifdef CONFIG_ZBUD > > + /* Allocated by zbud. Flag is necessary to find zbud pages to unuse > > + * during migration/compaction. > > + */ > > + PG_zbud, > > +#endif > > Do you _really_ need an absolutely new, unshared page flag? > The zbud code doesn't really look like it uses any of the space in > 'struct page'. > > I think you could pretty easily alias PG_zbud=PG_slab, then use the > page->{private,slab_cache} (or some other unused field) in 'struct page' > to store a cookie to differentiate slab and zbud pages.
How about using page->_mapcount with negative value (-129)? Just like PageBuddy()?
Best regards, Krzysztof
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