From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751500AbdA0V1r (ORCPT ); Fri, 27 Jan 2017 16:27:47 -0500 Received: from g2t1383g.austin.hpe.com ([15.233.16.89]:2147 "EHLO g2t1383g.austin.hpe.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751144AbdA0V1K (ORCPT ); Fri, 27 Jan 2017 16:27:10 -0500 From: Toshi Kani To: akpm@linux-foundation.org, gregkh@linuxfoundation.org Cc: linux-mm@kvack.org, zhenzhang.zhang@huawei.com, arbab@linux.vnet.ibm.com, dan.j.williams@intel.com, abanman@sgi.com, rientjes@google.com, linux-kernel@vger.kernel.org, stable@vger.kernel.org, toshi.kani@hpe.com Subject: [PATCH v2 0/2] fix a kernel oops when reading sysfs valid_zones Date: Fri, 27 Jan 2017 15:21:47 -0700 Message-Id: <20170127222149.30893-1-toshi.kani@hpe.com> X-Mailer: git-send-email 2.9.3 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org A sysfs memory file is created for each 2GiB memory block on x86-64 when the system has 64GiB or more memory. [1] When the start address of a memory block is not backed by struct page, i.e. a memory range is not aligned by 2GiB, reading its 'valid_zones' attribute file leads to a kernel oops. This issue was observed on multiple x86-64 systems with more than 64GiB of memory. This patch-set fixes this issue. Patch 1 first fixes an issue in test_pages_in_a_zone(), which does not test the start section. Patch 2 then fixes the kernel oops by extending test_pages_in_a_zone() to return valid [start, end). Note for stable kernels: The memory block size change was made by commit bdee237c034, which was accepted to 3.9. However, this patch-set depends on (and fixes) the change to test_pages_in_a_zone() made by commit 5f0f2887f4, which was accepted to 4.4. So, I recommend that we backport it up to 4.4. [1] 'Commit bdee237c0343 ("x86: mm: Use 2GB memory block size on large-memory x86-64 systems")' v2: - Rebase to the -mm tree. (Andrew Morton) - Add more descriptions about the issue. (Andrew Morton) - Add cc to stable kernels. (Greg Kroah-Hartman, Andrew Morton) --- Toshi Kani (2): 1/2 mm/memory_hotplug.c: check start_pfn in test_pages_in_a_zone() 2/2 base/memory, hotplug: fix a kernel oops in show_valid_zones() --- drivers/base/memory.c | 12 ++++++------ include/linux/memory_hotplug.h | 3 ++- mm/memory_hotplug.c | 28 +++++++++++++++++++++-------