Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S933883AbYBGUKI (ORCPT ); Thu, 7 Feb 2008 15:10:08 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1757980AbYBGUEG (ORCPT ); Thu, 7 Feb 2008 15:04:06 -0500 Received: from fg-out-1718.google.com ([72.14.220.152]:38645 "EHLO fg-out-1718.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1761693AbYBGUEE (ORCPT ); Thu, 7 Feb 2008 15:04:04 -0500 DomainKey-Signature: a=rsa-sha1; c=nofws; d=gmail.com; s=gamma; h=message-id:date:from:to:subject:mime-version:content-type:content-transfer-encoding:content-disposition; b=ET4m/YqFVntD5g9vnlingbUfJ1O08AWTx3MNNbmcUaQrqztnrgUF9F9HVWiFjaogceVdrnopk1PME6vlRl2psZKxV/jzkJFNmZnusDdC8ahXgoGM8y1rv1JP7Kbkm569Ek5TnmACjIoUDjU6J3aKXEUHFPdEvOrvLtsAbUXLqKo= Message-ID: <6101e8c40802071204n6613b13ue72b8df64f7a8522@mail.gmail.com> Date: Thu, 7 Feb 2008 21:04:01 +0100 From: "Oliver Pinter" To: "Linux Kernel" , stable@kernel.org, stable-commits@vger.kernel.org Subject: [2.6.22.y] {14+1} - NM!!! - Race condition in userspace testcase - on top of 2.6.22.17 MIME-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Content-Disposition: inline Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1360 Lines: 46 aka: do_anonymous_page-race.patch From: Andrea Arcangeli Subject: Race condition in userspace testcase References: 46948, LTC11574 NOT IN MAINLINE Additional Comment #103 From Andrea Arcangeli 2004-10-15 19:41 the last patch I attached is the safest I believe. I'm not sure if a lock_unlock or lock_unlock is always guaranteed to happen after the I/O, and this makes sure no race can happen anymore. --- fs/bio.c | 9 +++++++++ 1 file changed, 9 insertions(+) --- a/fs/bio.c 2007-07-08 19:32:17.000000000 -0400 +++ b/fs/bio.c 2007-08-27 14:01:21.000000000 -0400 @@ -1028,6 +1028,15 @@ void bio_endio(struct bio *bio, unsigned bio->bi_size -= bytes_done; bio->bi_sector += (bytes_done >> 9); + if (bio_data_dir(bio) == READ) + /* + * If the current cpu has written to the page by hand + * without dma, we must enforce ordering to be sure + * this written data will be visible before we expose + * the page contents to other cpus (for example with + * a set_pte). + */ + smp_wmb(); if (bio->bi_end_io) bio->bi_end_io(bio, bytes_done, error); } -- Thanks, Oliver -- 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/