Re: [patch 1/3] mm: decouple unevictable lru from mmu

[David Howells]

Johannes Weiner <hannes@xxxxxxxxxxx> wrote:

> David, why do we need two Kconfig symbols for mlock and the mlock page
> bit?  Don't we always provide mlock on mmu and never on nommu?

Because whilst the PG_mlocked doesn't exist if we don't have mlock() because
we're in NOMMU mode, that does not imply that it _does_ exist if we _do_ have
mlock() as it's also contingent on having the unevictable LRU.

Not only that, CONFIG_HAVE_MLOCK used in mm/internal.h to switch some stuff
out based on whether we have mlock() available or not - which is not the same
as whether we have PG_mlocked or not.

Mainly I thought it made the train of logic easier.

Note that neither symbol is actually manually adjustable.

David
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