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.

[[email protected]: tweak comment text, per Mel]
Signed-off-by: Minchan Kim <[email protected]>
Acked-by: Mel Gorman <[email protected]>
Cc: Michal Nazarewicz <[email protected]>
Cc: Bartlomiej Zolnierkiewicz <[email protected]>
Cc: Marek Szyprowski <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>
This commit is contained in:
Minchan Kim 2012-10-08 16:33:48 -07:00 • committed by Linus Torvalds
commit e46a28790e
5 changed files with 12 additions and 6 deletions

View file

@ -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