rmap: annotate lock context change on page_[un]lock_anon_vma()

The page_lock_anon_vma() conditionally grabs RCU and anon_vma lock but
page_unlock_anon_vma() releases them unconditionally.  This leads sparse
to complain about context imbalance.  Annotate them.

Signed-off-by: Namhyung Kim <namhyung@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 3 insertions, 1 deletions

diff --git a/mm/rmap.c b/mm/rmap.c
index f5ad996a4a8f..0995a8f68866 100644
--- a/mm/rmap.c
+++ b/mm/rmap.c
@@ -314,7 +314,7 @@ void __init anon_vma_init(void)
  * Getting a lock on a stable anon_vma from a page off the LRU is
  * tricky: page_lock_anon_vma rely on RCU to guard against the races.
  */
-struct anon_vma *page_lock_anon_vma(struct page *page)
+struct anon_vma *__page_lock_anon_vma(struct page *page)
 {
         struct anon_vma *anon_vma, *root_anon_vma;
         unsigned long anon_mapping;
@@ -348,6 +348,8 @@ out:
 }
 
 void page_unlock_anon_vma(struct anon_vma *anon_vma)
+        __releases(&anon_vma->root->lock)
+        __releases(RCU)
 {
         anon_vma_unlock(anon_vma);
         rcu_read_unlock();