From: Konstantin Khlebnikov <k.khlebni...@samsung.com> 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 <k.khlebni...@samsung.com> Cc: stable <sta...@vger.kernel.org> # v3.8 --- include/linux/balloon_compaction.h | 5 +++++ mm/migrate.c | 2 +- 2 files changed, 6 insertions(+), 1 deletion(-) diff --git a/include/linux/balloon_compaction.h b/include/linux/balloon_compaction.h index 53d482e..284fc1d 100644 --- a/include/linux/balloon_compaction.h +++ b/include/linux/balloon_compaction.h @@ -258,6 +258,11 @@ static inline void balloon_page_delete(struct page *page) list_del(&page->lru); } +static inline bool __is_movable_balloon_page(struct page *page) +{ + return false; +} + static inline bool balloon_page_movable(struct page *page) { return false; diff --git a/mm/migrate.c b/mm/migrate.c index 905b1aa..57c94f9 100644 --- a/mm/migrate.c +++ b/mm/migrate.c @@ -873,7 +873,7 @@ static int __unmap_and_move(struct page *page, struct page *newpage, } } - 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. -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/