The patch titled
Subject: mm/balloon_compaction: keep ballooned pages away from normal
migration path
has been added to the -mm tree. Its filename is
mm-balloon_compaction-keep-ballooned-pages-away-from-normal-migration-path.patch
This patch should soon appear at
http://ozlabs.org/~akpm/mmots/broken-out/mm-balloon_compaction-keep-ballooned-pages-away-from-normal-migration-path.patch
and later at
http://ozlabs.org/~akpm/mmotm/broken-out/mm-balloon_compaction-keep-ballooned-pages-away-from-normal-migration-path.patch
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------------------------------------------------------
From: Konstantin Khlebnikov <[email protected]>
Subject: mm/balloon_compaction: keep ballooned pages away from normal migration
path
Proper testing shows yet another problem in balloon migration: it works
only once for each page. balloon_page_movable() check page flags and
page_count. In __unmap_and_move page is locked, reference counter is
elevated, so balloon_page_movable() _always_ fails here. As result in
__unmap_and_move() migration goes to the normal migration path.
Balloon ->migratepage() is so special, it returns
MIGRATEPAGE_BALLOON_SUCCESS instead of MIGRATEPAGE_SUCCESS. After that in
move_to_new_page() successfully migrated page got NULL into its mapping
pointer and loses connectivity with balloon and ability for further
migration.
It's safe to use __is_movable_balloon_page here: page is isolated and pinned.
Signed-off-by: Konstantin Khlebnikov <[email protected]>
Acked-by: Rafael Aquini <[email protected]>
Cc: Andrey Ryabinin <[email protected]>
Cc: <[email protected]> [v3.8+]
Signed-off-by: Andrew Morton <[email protected]>
---
mm/migrate.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff -puN
mm/migrate.c~mm-balloon_compaction-keep-ballooned-pages-away-from-normal-migration-path
mm/migrate.c
---
a/mm/migrate.c~mm-balloon_compaction-keep-ballooned-pages-away-from-normal-migration-path
+++ a/mm/migrate.c
@@ -873,7 +873,7 @@ static int __unmap_and_move(struct page
}
}
- if (unlikely(balloon_page_movable(page))) {
+ if (unlikely(__is_movable_balloon_page(page))) {
/*
* A ballooned page does not need any special attention from
* physical to virtual reverse mapping procedures.
_
Patches currently in -mm which might be from [email protected] are
mm-balloon_compaction-ignore-anonymous-pages.patch
mm-balloon_compaction-keep-ballooned-pages-away-from-normal-migration-path.patch
mm-balloon_compaction-isolate-balloon-pages-without-lru_lock.patch
mm-introduce-common-page-state-for-ballooned-memory.patch
mm-balloon_compaction-use-common-page-ballooning.patch
mm-balloon_compaction-general-cleanup.patch
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