diff options
| author | Rafael Aquini <aquini@redhat.com> | 2012-12-12 04:02:38 +0400 |
|---|---|---|
| committer | Linus Torvalds <torvalds@linux-foundation.org> | 2012-12-12 05:22:26 +0400 |
| commit | 18468d93e53b037e1a04ec58398eab763d054064 (patch) | |
| tree | 74392b876400391567f55bb5292107b65e3791a2 /include/linux/migrate.h | |
| parent | 252aa6f5be64c90c67b9f066ccff880f6b487d32 (diff) | |
| download | linux-18468d93e53b037e1a04ec58398eab763d054064.tar.xz | |
mm: introduce a common interface for balloon pages mobility
Memory fragmentation introduced by ballooning might reduce significantly
the number of 2MB contiguous memory blocks that can be used within a guest,
thus imposing performance penalties associated with the reduced number of
transparent huge pages that could be used by the guest workload.
This patch introduces a common interface to help a balloon driver on
making its page set movable to compaction, and thus allowing the system
to better leverage the compation efforts on memory defragmentation.
[akpm@linux-foundation.org: use PAGE_FLAGS_CHECK_AT_PREP, s/__balloon_page_flags/page_flags_cleared/, small cleanups]
[rientjes@google.com: allow balloon compaction for any system with memory compaction enabled, which is the defconfig]
Signed-off-by: Rafael Aquini <aquini@redhat.com>
Acked-by: Mel Gorman <mel@csn.ul.ie>
Cc: Rusty Russell <rusty@rustcorp.com.au>
Cc: "Michael S. Tsirkin" <mst@redhat.com>
Cc: Rik van Riel <riel@redhat.com>
Cc: Andi Kleen <andi@firstfloor.org>
Cc: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Cc: Minchan Kim <minchan@kernel.org>
Signed-off-by: David Rientjes <rientjes@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'include/linux/migrate.h')
| -rw-r--r-- | include/linux/migrate.h | 10 |
1 files changed, 10 insertions, 0 deletions
diff --git a/include/linux/migrate.h b/include/linux/migrate.h index a4e886d17f87..ce42847ed35f 100644 --- a/include/linux/migrate.h +++ b/include/linux/migrate.h @@ -11,8 +11,18 @@ typedef struct page *new_page_t(struct page *, unsigned long private, int **); * Return values from addresss_space_operations.migratepage(): * - negative errno on page migration failure; * - zero on page migration success; + * + * The balloon page migration introduces this special case where a 'distinct' + * return code is used to flag a successful page migration to unmap_and_move(). + * This approach is necessary because page migration can race against balloon + * deflation procedure, and for such case we could introduce a nasty page leak + * if a successfully migrated balloon page gets released concurrently with + * migration's unmap_and_move() wrap-up steps. */ #define MIGRATEPAGE_SUCCESS 0 +#define MIGRATEPAGE_BALLOON_SUCCESS 1 /* special ret code for balloon page + * sucessful migration case. + */ #ifdef CONFIG_MIGRATION |