tree 574ead6bd03d31ca7036ff2389cb0400f3fd63fc
parent 3665d0e58fa44f50c744f85c7e8ad21d5b10e206
author Andrew Morton <akpm@osdl.org> 1157734118 -0700
committer Linus Torvalds <torvalds@g5.osdl.org> 1157736170 -0700

[PATCH] invalidate_complete_page() race fix

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 <nickpiggin@yahoo.com.au>
Cc: Hugh Dickins <hugh@veritas.com>
Cc: <stable@kernel.org>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>