From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-15.8 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER, INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 9613FC433EF for ; Thu, 2 Sep 2021 21:57:09 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 8419660F12 for ; Thu, 2 Sep 2021 21:57:09 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1347565AbhIBV6H (ORCPT ); Thu, 2 Sep 2021 17:58:07 -0400 Received: from mail.kernel.org ([198.145.29.99]:53602 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1347621AbhIBV6H (ORCPT ); Thu, 2 Sep 2021 17:58:07 -0400 Received: by mail.kernel.org (Postfix) with ESMTPSA id 06FF8603E9; Thu, 2 Sep 2021 21:57:08 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linux-foundation.org; s=korg; t=1630619828; bh=yBNIpuWA+haAXY9XTyt+VDgvjQE6XHxzpyp6siOX+ko=; h=Date:From:To:Subject:In-Reply-To:From; b=iypJShZmkBitnOgAjFXgF+TB55sv93a520BMNYRGkKtT/sHZhGG2HJ8f8pTJWGBnZ erenUmE8W+zoI4LCBfLxhnDYp/Rowj30Ii7poSoi3iF+FSkHID9IYBuUL0XEJMxeAY vpOg3e9WELuY3haDf1yQw2GND22F2H80WQsqpFnY= Date: Thu, 02 Sep 2021 14:57:07 -0700 From: Andrew Morton To: akpm@linux-foundation.org, dan.j.williams@intel.com, david@redhat.com, k-hagio-ab@nec.com, linux-mm@kvack.org, mm-commits@vger.kernel.org, naoya.horiguchi@nec.com, osalvador@suse.de, rui.xiang@huawei.com, torvalds@linux-foundation.org, wangwensheng4@huawei.com Subject: [patch 134/212] mm/sparse: set SECTION_NID_SHIFT to 6 Message-ID: <20210902215707.xt0_w1Gft%akpm@linux-foundation.org> In-Reply-To: <20210902144820.78957dff93d7bea620d55a89@linux-foundation.org> User-Agent: s-nail v14.8.16 Precedence: bulk Reply-To: linux-kernel@vger.kernel.org List-ID: X-Mailing-List: mm-commits@vger.kernel.org From: Naoya Horiguchi Subject: mm/sparse: set SECTION_NID_SHIFT to 6 Currently SECTION_NID_SHIFT is set to 3, which is incorrect because bit 3 and 4 can be overlapped by sub-field for early NID, and can be unexpectedly set on NUMA systems. There are a few non-critical issues related to this: - Having SECTION_TAINT_ZONE_DEVICE set for wrong sections forces pfn_to_online_page() through the slow path, but doesn't actually break the kernel. - A kdump generation tool like makedumpfile uses this field to calculate the physical address to read. So wrong bits can make the tool access to wrong address and fail to create kdump. This can be avoided by the tool, so it's not critical. To fix it, set SECTION_NID_SHIFT to 6 which is the minimum number of available bits of section flag field. Link: https://lkml.kernel.org/r/20210707045548.810271-1-naoya.horiguchi@linux.dev Fixes: 1f90a3477df3 ("mm: teach pfn_to_online_page() about ZONE_DEVICE section collisions") Signed-off-by: Naoya Horiguchi Reported-by: Kazuhito Hagio Suggested-by: Dan Williams Acked-by: David Hildenbrand Cc: Oscar Salvador Cc: Wang Wensheng Cc: Rui Xiang Cc: Kazu Cc: Naoya Horiguchi Signed-off-by: Andrew Morton --- include/linux/mmzone.h | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) --- a/include/linux/mmzone.h~mm-sparse-set-section_nid_shift-to-6 +++ a/include/linux/mmzone.h @@ -1364,7 +1364,7 @@ extern size_t mem_section_usage_size(voi #define SECTION_TAINT_ZONE_DEVICE (1UL<<4) #define SECTION_MAP_LAST_BIT (1UL<<5) #define SECTION_MAP_MASK (~(SECTION_MAP_LAST_BIT-1)) -#define SECTION_NID_SHIFT 3 +#define SECTION_NID_SHIFT 6 static inline struct page *__section_mem_map_addr(struct mem_section *section) { _