On Tue, Nov 20 2012, Marek Szyprowski wrote:
> Right now running out of 'plain' movable pages is the only possibility to
> get movable pages allocated from CMA. On the other hand running out of
> 'plain' movable pages is very deadly for the system, as movable pageblocks
> are also the main fallbacks for reclaimable and non-movable pages.
>
> Then, once we run out of movable pages and kernel needs non-mobable or
> reclaimable page (what happens quite often), it usually triggers OOM to
> satisfy the memory needs. Such OOM is very strange, especially on a system
> with dozen of megabytes of CMA memory, having most of them free at the OOM
> event. By high memory pressure I mean the high memory usage.

Would it make sense to *always* use MIGRATE_CMA for movable allocations
before MIGRATE_MOVABLE?  Ie. how about this patch (not tested):

------------------------- >8 -------------------------------------------------