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authorMel Gorman <mgorman@suse.de>2012-01-12 17:19:38 -0800
committerLinus Torvalds <torvalds@linux-foundation.org>2012-01-12 20:13:09 -0800
commitc82449352854ff09e43062246af86bdeb628f0c3 (patch)
tree9cb8052e425c8cdab24ac41e83bbb672832ce54e /mm
parentb969c4ab9f182a6e1b2a0848be349f99714947b0 (diff)
mm: compaction: make isolate_lru_page() filter-aware again
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>
Diffstat (limited to 'mm')
-rw-r--r--mm/compaction.c3
-rw-r--r--mm/vmscan.c35
2 files changed, 36 insertions, 2 deletions
diff --git a/mm/compaction.c b/mm/compaction.c
index d31e64becb38..fb291585e1bf 100644
--- a/mm/compaction.c
+++ b/mm/compaction.c
@@ -349,6 +349,9 @@ static isolate_migrate_t isolate_migratepages(struct zone *zone,
continue;
}
+ if (!cc->sync)
+ mode |= ISOLATE_ASYNC_MIGRATE;
+
/* Try isolate the page */
if (__isolate_lru_page(page, mode, 0) != 0)
continue;
diff --git a/mm/vmscan.c b/mm/vmscan.c
index cb68c53db4ec..efbcab1c8f54 100644
--- a/mm/vmscan.c
+++ b/mm/vmscan.c
@@ -1075,8 +1075,39 @@ int __isolate_lru_page(struct page *page, isolate_mode_t mode, int file)
ret = -EBUSY;
- if ((mode & ISOLATE_CLEAN) && (PageDirty(page) || PageWriteback(page)))
- return ret;
+ /*
+ * To minimise LRU disruption, the caller can indicate that it only
+ * wants to isolate pages it will be able to operate on without
+ * blocking - clean pages for the most part.
+ *
+ * ISOLATE_CLEAN means that only clean pages should be isolated. This
+ * is used by reclaim when it is cannot write to backing storage
+ *
+ * ISOLATE_ASYNC_MIGRATE is used to indicate that it only wants to pages
+ * that it is possible to migrate without blocking
+ */
+ if (mode & (ISOLATE_CLEAN|ISOLATE_ASYNC_MIGRATE)) {
+ /* All the caller can do on PageWriteback is block */
+ if (PageWriteback(page))
+ return ret;
+
+ if (PageDirty(page)) {
+ struct address_space *mapping;
+
+ /* ISOLATE_CLEAN means only clean pages */
+ if (mode & ISOLATE_CLEAN)
+ return ret;
+
+ /*
+ * Only pages without mappings or that have a
+ * ->migratepage callback are possible to migrate
+ * without blocking
+ */
+ mapping = page_mapping(page);
+ if (mapping && !mapping->a_ops->migratepage)
+ return ret;
+ }
+ }
if ((mode & ISOLATE_UNMAPPED) && page_mapped(page))
return ret;

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