From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754314Ab2ISDwW (ORCPT ); Tue, 18 Sep 2012 23:52:22 -0400 Received: from mail-qa0-f53.google.com ([209.85.216.53]:64400 "EHLO mail-qa0-f53.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752188Ab2ISDwU (ORCPT ); Tue, 18 Sep 2012 23:52:20 -0400 Date: Tue, 18 Sep 2012 20:51:47 -0700 (PDT) From: Hugh Dickins X-X-Sender: hugh@eggly.anvils To: Andrew Morton cc: Sasha Levin , Mel Gorman , Rik van Riel , Johannes Weiner , Michel Lespinasse , Ying Han , linux-mm@kvack.org, linux-kernel@vger.kernel.org Subject: [PATCH 1/4] mm: fix invalidate_complete_page2 lock ordering Message-ID: User-Agent: Alpine 2.00 (LSU 1167 2008-08-23) MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org In fuzzing with trinity, lockdep protested "possible irq lock inversion dependency detected" when isolate_lru_page() reenabled interrupts while still holding the supposedly irq-safe tree_lock: invalidate_inode_pages2 invalidate_complete_page2 spin_lock_irq(&mapping->tree_lock) clear_page_mlock isolate_lru_page spin_unlock_irq(&zone->lru_lock) isolate_lru_page() is correct to enable interrupts unconditionally: invalidate_complete_page2() is incorrect to call clear_page_mlock() while holding tree_lock, which is supposed to nest inside lru_lock. Both truncate_complete_page() and invalidate_complete_page() call clear_page_mlock() before taking tree_lock to remove page from radix_tree. I guess invalidate_complete_page2() preferred to test PageDirty (again) under tree_lock before committing to the munlock; but since the page has already been unmapped, its state is already somewhat inconsistent, and no worse if clear_page_mlock() moved up. Reported-by: Sasha Levin Deciphered-by: Andrew Morton Signed-off-by: Hugh Dickins Cc: Mel Gorman Cc: Rik van Riel Cc: Johannes Weiner Cc: Michel Lespinasse Cc: Ying Han Cc: stable@vger.kernel.org --- mm/truncate.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) --- 3.6-rc6.orig/mm/truncate.c 2012-09-18 15:38:08.000000000 -0700 +++ 3.6-rc6/mm/truncate.c 2012-09-18 15:42:17.066731792 -0700 @@ -394,11 +394,12 @@ invalidate_complete_page2(struct address if (page_has_private(page) && !try_to_release_page(page, GFP_KERNEL)) return 0; + clear_page_mlock(page); + spin_lock_irq(&mapping->tree_lock); if (PageDirty(page)) goto failed; - clear_page_mlock(page); BUG_ON(page_has_private(page)); __delete_from_page_cache(page); spin_unlock_irq(&mapping->tree_lock);