Introduce migrate_replace_page() function for migrating single page to the given target page.
Signed-off-by: Marek Szyprowski m.szyprowski@samsung.com Signed-off-by: Kyungmin Park kyungmin.park@samsung.com --- include/linux/migrate.h | 5 ++++ mm/migrate.c | 59 +++++++++++++++++++++++++++++++++++++++++++++++ 2 files changed, 64 insertions(+)
diff --git a/include/linux/migrate.h b/include/linux/migrate.h index a405d3dc..3a8a6c1 100644 --- a/include/linux/migrate.h +++ b/include/linux/migrate.h @@ -35,6 +35,8 @@ enum migrate_reason {
#ifdef CONFIG_MIGRATION
+extern int migrate_replace_page(struct page *oldpage, struct page *newpage); + extern void putback_lru_pages(struct list_head *l); extern void putback_movable_pages(struct list_head *l); extern int migrate_page(struct address_space *, @@ -57,6 +59,9 @@ extern int migrate_huge_page_move_mapping(struct address_space *mapping, struct page *newpage, struct page *page); #else
+static inline int migrate_replace_page(struct page *oldpage, + struct page *newpage) { return -ENOSYS; } + static inline void putback_lru_pages(struct list_head *l) {} static inline void putback_movable_pages(struct list_head *l) {} static inline int migrate_pages(struct list_head *l, new_page_t x, diff --git a/mm/migrate.c b/mm/migrate.c index 3bbaf5d..a2a6950 100644 --- a/mm/migrate.c +++ b/mm/migrate.c @@ -1067,6 +1067,65 @@ out: return rc; }
+/* + * migrate_replace_page + * + * The function takes one single page and a target page (newpage) and + * tries to migrate data to the target page. The caller must ensure that + * the source page is locked with one additional get_page() call, which + * will be freed during the migration. The caller also must release newpage + * if migration fails, otherwise the ownership of the newpage is taken. + * Source page is released if migration succeeds. + * + * Return: error code or 0 on success. + */ +int migrate_replace_page(struct page *page, struct page *newpage) +{ + struct zone *zone = page_zone(page); + unsigned long flags; + int ret = -EAGAIN; + int pass; + + migrate_prep(); + + spin_lock_irqsave(&zone->lru_lock, flags); + + if (PageLRU(page) && + __isolate_lru_page(page, ISOLATE_UNEVICTABLE) == 0) { + struct lruvec *lruvec = mem_cgroup_page_lruvec(page, zone); + del_page_from_lru_list(page, lruvec, page_lru(page)); + spin_unlock_irqrestore(&zone->lru_lock, flags); + } else { + spin_unlock_irqrestore(&zone->lru_lock, flags); + return -EAGAIN; + } + + /* page is now isolated, so release additional reference */ + put_page(page); + + for (pass = 0; pass < 10 && ret != 0; pass++) { + cond_resched(); + + if (page_count(page) == 1) { + /* page was freed from under us, so we are done */ + ret = 0; + break; + } + ret = __unmap_and_move(page, newpage, 1, MIGRATE_SYNC); + } + + if (ret == 0) { + /* take ownership of newpage and add it to lru */ + putback_lru_page(newpage); + } else { + /* restore additional reference to the oldpage */ + get_page(page); + } + + putback_lru_page(page); + return ret; +} + #ifdef CONFIG_NUMA /* * Move a list of individual pages