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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