Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756800Ab3CFXKh (ORCPT ); Wed, 6 Mar 2013 18:10:37 -0500 Received: from e35.co.us.ibm.com ([32.97.110.153]:40689 "EHLO e35.co.us.ibm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754116Ab3CFXKg (ORCPT ); Wed, 6 Mar 2013 18:10:36 -0500 Subject: [PATCH] do not try to sync identity map for non-mapped pages To: linux-kernel@vger.kernel.org Cc: bp@alien8.de, hpa@linux.intel.com, penguin-kernel@i-love.sakura.ne.jp, Dave Hansen From: Dave Hansen Date: Wed, 06 Mar 2013 15:10:09 -0800 Message-Id: <20130306231009.D782087E@kernel.stglabs.ibm.com> X-TM-AS-MML: No X-Content-Scanned: Fidelis XPS MAILER x-cbid: 13030623-4834-0000-0000-0000046418CE Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1930 Lines: 50 kernel_map_sync_memtype() is called from a variety of contexts. The pat.c code that calls it seems to ensure that it is not called for non-ram areas by checking via pat_pagerange_is_ram(). It is important that it only be called on the actual identity map because there *IS* no map to sync for highmem pages, or for memory holes. The ioremap.c uses are not as careful as those from pat.c, and call kernel_map_sync_memtype() on PCI space which is in the middle of the kernel identity map _range_, but is not actually mapped. This patch adds a check to kernel_map_sync_memtype() which probably duplicates some of the checks already in pat.c. But, it is necessary for the ioremap.c uses and shouldn't hurt other callers. I have reproduced this bug and this patch fixes it for me https://lkml.org/lkml/2013/2/5/396 Signed-off-by: Dave Hansen --- linux-2.6.git-dave/arch/x86/mm/pat.c | 7 +++++++ 1 file changed, 7 insertions(+) diff -puN arch/x86/mm/pat.c~dont-flush-map-for-non-ram-pages arch/x86/mm/pat.c --- linux-2.6.git/arch/x86/mm/pat.c~dont-flush-map-for-non-ram-pages 2013-03-06 15:03:56.403628100 -0800 +++ linux-2.6.git-dave/arch/x86/mm/pat.c 2013-03-06 15:03:56.419628258 -0800 @@ -563,6 +563,13 @@ int kernel_map_sync_memtype(u64 base, un if (base > __pa(high_memory-1)) return 0; + /* + * some areas in the middle of the kernel identity range + * are not mapped, like the PCI space. + */ + if (!page_is_ram(base >> PAGE_SHIFT)) + return 0; + id_sz = (__pa(high_memory-1) <= base + size) ? __pa(high_memory) - base : size; diff -puN arch/x86/mm/ioremap.c~dont-flush-map-for-non-ram-pages arch/x86/mm/ioremap.c _ -- 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/