From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1759619Ab1LPIE0 (ORCPT ); Fri, 16 Dec 2011 03:04:26 -0500 Received: from cantor2.suse.de ([195.135.220.15]:60044 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751300Ab1LPIEY (ORCPT ); Fri, 16 Dec 2011 03:04:24 -0500 From: Petr Tesarik Organization: SUSE LINUX, s.r.o. To: Tejun Heo , linux-mm@kvack.org Subject: [PATCH] Do not round per_cpu_ptr_to_phys to page boundary Date: Fri, 16 Dec 2011 09:04:23 +0100 User-Agent: KMail/1.13.6 (Linux/2.6.37.6-0.9-default; KDE/4.6.0; i686; ; ) Cc: LKML , Vivek Goyal , surovegin@google.com, gthelen@google.com References: <201112140033.58951.ptesarik@suse.cz> <201112151139.32224.ptesarik@suse.cz> In-Reply-To: MIME-Version: 1.0 Content-Type: Text/Plain; charset="iso-8859-1" Content-Transfer-Encoding: 7bit Message-Id: <201112160904.23252.ptesarik@suse.cz> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org The phys_addr_t per_cpu_ptr_to_phys() function ignores the offset within a page, whenever not using a simple translation using __pa(). Without this patch /sys/devices/system/cpu/cpu*/crash_notes shows incorrect values, which breaks kdump. Other things may also be broken. Signed-off-by: Petr Tesarik diff --git a/mm/percpu.c b/mm/percpu.c index 3bb810a..1a1b5ac 100644 --- a/mm/percpu.c +++ b/mm/percpu.c @@ -998,6 +998,7 @@ phys_addr_t per_cpu_ptr_to_phys(void *addr) bool in_first_chunk = false; unsigned long first_low, first_high; unsigned int cpu; + phys_addr_t page_addr; /* * The following test on unit_low/high isn't strictly @@ -1023,9 +1024,10 @@ phys_addr_t per_cpu_ptr_to_phys(void *addr) if (!is_vmalloc_addr(addr)) return __pa(addr); else - return page_to_phys(vmalloc_to_page(addr)); + page_addr = page_to_phys(vmalloc_to_page(addr)); } else - return page_to_phys(pcpu_addr_to_page(addr)); + page_addr = page_to_phys(pcpu_addr_to_page(addr)); + return page_addr + offset_in_page(addr); } /**