-stable review patch. If anyone has any objections, please let us know.
------------------
From: Andrew Morton <[email protected]>
If a CPU faults this page into pagetables after invalidate_mapping_pages()
checked page_mapped(), invalidate_complete_page() will still proceed to remove
the page from pagecache. This leaves the page-faulting process with a
detached page. If it was MAP_SHARED then file data loss will ensue.
Fix that up by checking the page's refcount after taking tree_lock.
Cc: Nick Piggin <[email protected]>
Cc: Hugh Dickins <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Greg Kroah-Hartman <[email protected]>
---
mm/truncate.c | 11 +++++++----
1 file changed, 7 insertions(+), 4 deletions(-)
--- linux-2.6.17.13.orig/mm/truncate.c
+++ linux-2.6.17.13/mm/truncate.c
@@ -68,10 +68,10 @@ invalidate_complete_page(struct address_
return 0;
write_lock_irq(&mapping->tree_lock);
- if (PageDirty(page)) {
- write_unlock_irq(&mapping->tree_lock);
- return 0;
- }
+ if (PageDirty(page))
+ goto failed;
+ if (page_count(page) != 2) /* caller's ref + pagecache ref */
+ goto failed;
BUG_ON(PagePrivate(page));
__remove_from_page_cache(page);
@@ -79,6 +79,9 @@ invalidate_complete_page(struct address_
ClearPageUptodate(page);
page_cache_release(page); /* pagecache ref */
return 1;
+failed:
+ write_unlock_irq(&mapping->tree_lock);
+ return 0;
}
/**
--
-
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