Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752414AbZGaCKv (ORCPT ); Thu, 30 Jul 2009 22:10:51 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1751452AbZGaCKu (ORCPT ); Thu, 30 Jul 2009 22:10:50 -0400 Received: from hera.kernel.org ([140.211.167.34]:45345 "EHLO hera.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750876AbZGaCKt (ORCPT ); Thu, 30 Jul 2009 22:10:49 -0400 Date: Fri, 31 Jul 2009 02:07:01 GMT From: "tip-bot for Pallipadi, Venkatesh" To: linux-tip-commits@vger.kernel.org Cc: linux-kernel@vger.kernel.org, hpa@zytor.com, mingo@redhat.com, venkatesh.pallipadi@intel.com, suresh.b.siddha@intel.com, airlied@redhat.com, tglx@linutronix.de, glisse@freedesktop.org Reply-To: mingo@redhat.com, hpa@zytor.com, linux-kernel@vger.kernel.org, venkatesh.pallipadi@intel.com, airlied@redhat.com, suresh.b.siddha@intel.com, tglx@linutronix.de, glisse@freedesktop.org In-Reply-To: <20090730214319.GA1889@linux-os.sc.intel.com> References: <20090730214319.GA1889@linux-os.sc.intel.com> Subject: [tip:x86/urgent] x86, pat: Fix set_memory_wc related corruption Message-ID: Git-Commit-ID: bdc6340f4eb68295b1e7c0ade2356b56dca93d93 X-Mailer: tip-git-log-daemon MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Disposition: inline X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.0 (hera.kernel.org [127.0.0.1]); Fri, 31 Jul 2009 02:07:02 +0000 (UTC) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 3043 Lines: 74 Commit-ID: bdc6340f4eb68295b1e7c0ade2356b56dca93d93 Gitweb: http://git.kernel.org/tip/bdc6340f4eb68295b1e7c0ade2356b56dca93d93 Author: Pallipadi, Venkatesh AuthorDate: Thu, 30 Jul 2009 14:43:19 -0700 Committer: H. Peter Anvin CommitDate: Thu, 30 Jul 2009 17:48:34 -0700 x86, pat: Fix set_memory_wc related corruption Changeset 3869c4aa18835c8c61b44bd0f3ace36e9d3b5bd0 that went in after 2.6.30-rc1 was a seemingly small change to _set_memory_wc() to make it complaint with SDM requirements. But, introduced a nasty bug, which can result in crash and/or strange corruptions when set_memory_wc is used. One such crash reported here http://lkml.org/lkml/2009/7/30/94 Actually, that changeset introduced two bugs. * change_page_attr_set() takes &addr as first argument and can the addr value might have changed on return, even for single page change_page_attr_set() call. That will make the second change_page_attr_set() in this routine operate on unrelated addr, that can eventually cause strange corruptions and bad page state crash. * The second change_page_attr_set() call, before setting _PAGE_CACHE_WC, should clear the earlier _PAGE_CACHE_UC_MINUS, as otherwise cache attribute will not be WC (will be UC instead). The patch below fixes both these problems. Sending a single patch to fix both the problems, as the change is to the same line of code. The change to have a addr_copy is not very clean. But, it is simpler than making more changes through various routines in pageattr.c. A huge thanks to Jerome for reporting this problem and providing a simple test case that helped us root cause the problem. Reported-by: Jerome Glisse Signed-off-by: Venkatesh Pallipadi Signed-off-by: Suresh Siddha LKML-Reference: <20090730214319.GA1889@linux-os.sc.intel.com> Acked-by: Dave Airlie Signed-off-by: H. Peter Anvin --- arch/x86/mm/pageattr.c | 9 ++++++--- 1 files changed, 6 insertions(+), 3 deletions(-) diff --git a/arch/x86/mm/pageattr.c b/arch/x86/mm/pageattr.c index 1b734d7..895d90e 100644 --- a/arch/x86/mm/pageattr.c +++ b/arch/x86/mm/pageattr.c @@ -997,12 +997,15 @@ EXPORT_SYMBOL(set_memory_array_uc); int _set_memory_wc(unsigned long addr, int numpages) { int ret; + unsigned long addr_copy = addr; + ret = change_page_attr_set(&addr, numpages, __pgprot(_PAGE_CACHE_UC_MINUS), 0); - if (!ret) { - ret = change_page_attr_set(&addr, numpages, - __pgprot(_PAGE_CACHE_WC), 0); + ret = change_page_attr_set_clr(&addr_copy, numpages, + __pgprot(_PAGE_CACHE_WC), + __pgprot(_PAGE_CACHE_MASK), + 0, 0, NULL); } return ret; } -- 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/