CMA: migrate mlocked pages

Presently CMA cannot migrate mlocked pages so it ends up failing to allocate
contiguous memory space.

This patch makes mlocked pages be migrated out.  Of course, it can affect
realtime processes but in CMA usecase, contiguous memory allocation failing
is far worse than access latency to an mlocked page being variable while
CMA is running.  If someone wants to make the system realtime, he shouldn't
enable CMA because stalls can still happen at random times.

[akpm@linux-foundation.org: tweak comment text, per Mel]
Signed-off-by: Minchan Kim <minchan@kernel.org>
Acked-by: Mel Gorman <mgorman@suse.de>
Cc: Michal Nazarewicz <mina86@mina86.com>
Cc: Bartlomiej Zolnierkiewicz <b.zolnierkie@samsung.com>
Cc: Marek Szyprowski <m.szyprowski@samsung.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 1 insertions, 1 deletions

diff --git a/mm/internal.h b/mm/internal.h
index 4dc93e2fe69e..f5f295fe11e1 100644
--- a/mm/internal.h
+++ b/mm/internal.h
@@ -138,7 +138,7 @@ isolate_freepages_range(struct compact_control *cc,
                         unsigned long start_pfn, unsigned long end_pfn);
 unsigned long
 isolate_migratepages_range(struct zone *zone, struct compact_control *cc,
-                           unsigned long low_pfn, unsigned long end_pfn);
+        unsigned long low_pfn, unsigned long end_pfn, bool unevictable);
 
 #endif