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| author | Andrew Morton <akpm@osdl.org> | 2006-09-08 09:48:38 -0700 |
|---|---|---|
| committer | Linus Torvalds <torvalds@g5.osdl.org> | 2006-09-08 10:22:50 -0700 |
| commit | 016eb4a0ed06a3677d67a584da901f0e9a63c666 (patch) | |
| tree | 574ead6bd03d31ca7036ff2389cb0400f3fd63fc | |
| parent | 3665d0e58fa44f50c744f85c7e8ad21d5b10e206 (diff) | |
| download | blackbird-op-linux-016eb4a0ed06a3677d67a584da901f0e9a63c666.tar.gz blackbird-op-linux-016eb4a0ed06a3677d67a584da901f0e9a63c666.zip | |
[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>
| -rw-r--r-- | mm/truncate.c | 11 |
1 files changed, 7 insertions, 4 deletions
diff --git a/mm/truncate.c b/mm/truncate.c index cf1b015df4a7..c6ab55ec6883 100644 --- a/mm/truncate.c +++ b/mm/truncate.c @@ -68,10 +68,10 @@ invalidate_complete_page(struct address_space *mapping, struct page *page) 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_space *mapping, struct page *page) ClearPageUptodate(page); page_cache_release(page); /* pagecache ref */ return 1; +failed: + write_unlock_irq(&mapping->tree_lock); + return 0; } /** |
