Messages in this thread Patch in this message |  | | | Date | Tue, 10 Oct 2006 10:14:51 -0700 | | From | Greg KH <> | | Subject | [patch 07/19] invalidate_complete_page() race fix |
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-stable review patch. If anyone has any objections, please let us know.
------------------ From: Andrew Morton <akpm@osdl.org> 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> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
--- 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; } /** -- - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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