[PATCH] mm: rmap with inner ptlock

rmap's page_check_address descend without page_table_lock.  First just
pte_offset_map in case there's no pte present worth locking for, then take
page_table_lock for the full check, and pass ptl back to caller in the same
style as pte_offset_map_lock.  __xip_unmap, page_referenced_one and
try_to_unmap_one use pte_unmap_unlock.  try_to_unmap_cluster also.

page_check_address reformatted to avoid progressive indentation.  No use is
made of its one error code, return NULL when it fails.

Signed-off-by: Hugh Dickins <hugh@veritas.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

1 files changed, 2 insertions, 2 deletions

diff --git a/include/linux/rmap.h b/include/linux/rmap.h
index e80fb7ee6efd..35b30e6c8cf8 100644
--- a/include/linux/rmap.h
+++ b/include/linux/rmap.h
@@ -95,8 +95,8 @@ int try_to_unmap(struct page *);
 /*
  * Called from mm/filemap_xip.c to unmap empty zero page
  */
-pte_t *page_check_address(struct page *, struct mm_struct *, unsigned long);
-
+pte_t *page_check_address(struct page *, struct mm_struct *,
+                                unsigned long, spinlock_t **);
 
 /*
  * Used by swapoff to help locate where page is expected in vma.