Re: [PATCH] mm: cma: allocate pages from CMA if NR_FREE_PAGES approaches low water mark
From: Michal Nazarewicz <hidden>
Date: 2012-11-20 15:41:23
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Subsystem:
memory management, memory management - page allocator, the rest · Maintainers:
Andrew Morton, Vlastimil Babka, Linus Torvalds
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 -------------------------------------------------