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-rw-r--r--mm/migrate.c11
1 files changed, 9 insertions, 2 deletions
diff --git a/mm/migrate.c b/mm/migrate.c
index 37c73b902008..e2fdbce1874b 100644
--- a/mm/migrate.c
+++ b/mm/migrate.c
@@ -611,6 +611,7 @@ static int unmap_and_move(new_page_t get_new_page, unsigned long private,
int rc = 0;
int *result = NULL;
struct page *newpage = get_new_page(page, private, &result);
+ int rcu_locked = 0;
if (!newpage)
return -ENOMEM;
@@ -636,8 +637,13 @@ static int unmap_and_move(new_page_t get_new_page, unsigned long private,
* we cannot notice that anon_vma is freed while we migrates a page.
* This rcu_read_lock() delays freeing anon_vma pointer until the end
* of migration. File cache pages are no problem because of page_lock()
+ * File Caches may use write_page() or lock_page() in migration, then,
+ * just care Anon page here.
*/
- rcu_read_lock();
+ if (PageAnon(page)) {
+ rcu_read_lock();
+ rcu_locked = 1;
+ }
/*
* This is a corner case handling.
* When a new swap-cache is read into, it is linked to LRU
@@ -656,7 +662,8 @@ static int unmap_and_move(new_page_t get_new_page, unsigned long private,
if (rc)
remove_migration_ptes(page, page);
rcu_unlock:
- rcu_read_unlock();
+ if (rcu_locked)
+ rcu_read_unlock();
unlock: