mm: mmzone: MIGRATE_CMA migration type added
The MIGRATE_CMA migration type has two main characteristics: (i) only movable pages can be allocated from MIGRATE_CMA pageblocks and (ii) page allocator will never change migration type of MIGRATE_CMA pageblocks. This guarantees (to some degree) that page in a MIGRATE_CMA page block can always be migrated somewhere else (unless there's no memory left in the system). It is designed to be used for allocating big chunks (eg. 10MiB) of physically contiguous memory. Once driver requests contiguous memory, pages from MIGRATE_CMA pageblocks may be migrated away to create a contiguous block. To minimise number of migrations, MIGRATE_CMA migration type is the last type tried when page allocator falls back to other migration types when requested. Signed-off-by: NMichal Nazarewicz <mina86@mina86.com> Signed-off-by: NMarek Szyprowski <m.szyprowski@samsung.com> Signed-off-by: NKyungmin Park <kyungmin.park@samsung.com> Acked-by: NMel Gorman <mel@csn.ul.ie> Reviewed-by: NKAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Tested-by: NRob Clark <rob.clark@linaro.org> Tested-by: NOhad Ben-Cohen <ohad@wizery.com> Tested-by: NBenjamin Gaignard <benjamin.gaignard@linaro.org> Tested-by: NRobert Nelson <robertcnelson@gmail.com> Tested-by: NBarry Song <Baohua.Song@csr.com>
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