mm: compaction: make isolate_lru_page() filter-aware again

commit c82449352854ff09e43062246af86bdeb628f0c3 upstream.

Stable note: Not tracked in Bugzilla. A fix aimed at preserving page aging
	information by reducing LRU list churning had the side-effect of
	reducing THP allocation success rates. This was part of a series
	to restore the success rates while preserving the reclaim fix.

Commit 39deaf85 ("mm: compaction: make isolate_lru_page() filter-aware")
noted that compaction does not migrate dirty or writeback pages and that
is was meaningless to pick the page and re-add it to the LRU list.  This
had to be partially reverted because some dirty pages can be migrated by
compaction without blocking.

This patch updates "mm: compaction: make isolate_lru_page" by skipping
over pages that migration has no possibility of migrating to minimise LRU
disruption.

Signed-off-by: Mel Gorman <mgorman@suse.de>
Reviewed-by: Rik van Riel<riel@redhat.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Reviewed-by: Minchan Kim <minchan@kernel.org>
Cc: Dave Jones <davej@redhat.com>
Cc: Jan Kara <jack@suse.cz>
Cc: Andy Isaacson <adi@hexapodia.org>
Cc: Nai Xia <nai.xia@gmail.com>
Cc: Johannes Weiner <jweiner@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

1 files changed, 2 insertions, 0 deletions

diff --git a/include/linux/mmzone.h b/include/linux/mmzone.h
index 80acfbc9aa1..b32f3f9182c 100644
--- a/include/linux/mmzone.h
+++ b/include/linux/mmzone.h
@@ -166,6 +166,8 @@ static inline int is_unevictable_lru(enum lru_list l)
 #define ISOLATE_CLEAN           ((__force isolate_mode_t)0x4)
 /* Isolate unmapped file */
 #define ISOLATE_UNMAPPED        ((__force isolate_mode_t)0x8)
+/* Isolate for asynchronous migration */
+#define ISOLATE_ASYNC_MIGRATE   ((__force isolate_mode_t)0x10)
 
 /* LRU Isolation modes. */
 typedef unsigned __bitwise__ isolate_mode_t;