Re: [RFC PATCH 3/4] mm: add zbud flag to page flags

From: Dave Hansen
Date: Tue Aug 06 2013 - 12:58:53 EST


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.
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