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=-12.0 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI, MENTIONS_GIT_HOSTING,SIGNED_OFF_BY,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 74D5BC43387 for ; Tue, 18 Dec 2018 12:43:07 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 48600217D9 for ; Tue, 18 Dec 2018 12:43:07 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726650AbeLRMnF (ORCPT ); Tue, 18 Dec 2018 07:43:05 -0500 Received: from terminus.zytor.com ([198.137.202.136]:50575 "EHLO terminus.zytor.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726403AbeLRMnE (ORCPT ); Tue, 18 Dec 2018 07:43:04 -0500 Received: from terminus.zytor.com (localhost [127.0.0.1]) by terminus.zytor.com (8.15.2/8.15.2) with ESMTPS id wBICgqKh2834007 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=NO); Tue, 18 Dec 2018 04:42:52 -0800 Received: (from tipbot@localhost) by terminus.zytor.com (8.15.2/8.15.2/Submit) id wBICgqer2833999; Tue, 18 Dec 2018 04:42:52 -0800 Date: Tue, 18 Dec 2018 04:42:52 -0800 X-Authentication-Warning: terminus.zytor.com: tipbot set sender to tipbot@zytor.com using -f From: tip-bot for Hui Wang Message-ID: Cc: qiaonuohan@huawei.com, wencongyang2@huawei.com, douliyang1@huawei.com, john.wanghui@huawei.com, guijianfeng@huawei.com, linux-kernel@vger.kernel.org, mingo@kernel.org, tglx@linutronix.de, hpa@zytor.com Reply-To: hpa@zytor.com, mingo@kernel.org, tglx@linutronix.de, linux-kernel@vger.kernel.org, guijianfeng@huawei.com, john.wanghui@huawei.com, wencongyang2@huawei.com, douliyang1@huawei.com, qiaonuohan@huawei.com In-Reply-To: <20181107023643.22174-1-john.wanghui@huawei.com> References: <20181107023643.22174-1-john.wanghui@huawei.com> To: linux-tip-commits@vger.kernel.org Subject: [tip:x86/cpu] x86/topology: Use total_cpus for max logical packages calculation Git-Commit-ID: aa02ef099cff042c2a9109782ec2bf1bffc955d4 X-Mailer: tip-git-log-daemon Robot-ID: Robot-Unsubscribe: Contact to get blacklisted from these emails MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Content-Type: text/plain; charset=UTF-8 Content-Disposition: inline Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Commit-ID: aa02ef099cff042c2a9109782ec2bf1bffc955d4 Gitweb: https://git.kernel.org/tip/aa02ef099cff042c2a9109782ec2bf1bffc955d4 Author: Hui Wang AuthorDate: Wed, 7 Nov 2018 10:36:43 +0800 Committer: Thomas Gleixner CommitDate: Tue, 18 Dec 2018 13:38:37 +0100 x86/topology: Use total_cpus for max logical packages calculation nr_cpu_ids can be limited on the command line via nr_cpus=. This can break the logical package management because it results in a smaller number of packages while in kdump kernel. Check below case: There is a two sockets system, each socket has 8 cores, which has 16 logical cpus while HT was turn on. 0 1 2 3 4 5 6 7 | 16 17 18 19 20 21 22 23 cores on socket 0 threads on socket 0 8 9 10 11 12 13 14 15 | 24 25 26 27 28 29 30 31 cores on socket 1 threads on socket 1 While starting the kdump kernel with command line option nr_cpus=16 panic was triggered on one of the cpus 24-31 eg. 26, then online cpu will be 1-15, 26(cpu 0 was disabled in kdump), ncpus will be 16 and __max_logical_packages will be 1, but actually two packages were booted on. This issue can reproduced by set kdump option nr_cpus=, and then trigger panic on last socket's thread, for example: taskset -c 26 echo c > /proc/sysrq-trigger Use total_cpus which will not be limited by nr_cpus command line to calculate the value of __max_logical_packages. Signed-off-by: Hui Wang Signed-off-by: Thomas Gleixner Cc: Cc: Cc: Cc: Link: https://lkml.kernel.org/r/20181107023643.22174-1-john.wanghui@huawei.com --- arch/x86/kernel/smpboot.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/arch/x86/kernel/smpboot.c b/arch/x86/kernel/smpboot.c index a9134d1910b9..ccd1f2a8e557 100644 --- a/arch/x86/kernel/smpboot.c +++ b/arch/x86/kernel/smpboot.c @@ -1347,7 +1347,7 @@ void __init calculate_max_logical_packages(void) * extrapolate the boot cpu's data to all packages. */ ncpus = cpu_data(0).booted_cores * topology_max_smt_threads(); - __max_logical_packages = DIV_ROUND_UP(nr_cpu_ids, ncpus); + __max_logical_packages = DIV_ROUND_UP(total_cpus, ncpus); pr_info("Max logical packages: %u\n", __max_logical_packages); }