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=-8.8 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,FREEMAIL_FORGED_FROMDOMAIN,FREEMAIL_FROM, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_PASS,USER_AGENT_GIT autolearn=unavailable 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 7151DC4360F for ; Mon, 25 Mar 2019 13:51:40 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 3986B20830 for ; Mon, 25 Mar 2019 13:51:40 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="cJe2vQt5" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729088AbfCYNvi (ORCPT ); Mon, 25 Mar 2019 09:51:38 -0400 Received: from mail-pg1-f193.google.com ([209.85.215.193]:42946 "EHLO mail-pg1-f193.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726166AbfCYNvi (ORCPT ); Mon, 25 Mar 2019 09:51:38 -0400 Received: by mail-pg1-f193.google.com with SMTP id p6so6624581pgh.9; Mon, 25 Mar 2019 06:51:38 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=from:to:cc:subject:date:message-id; bh=GT4Bk9dT9oL1IWkeLESxHzy5fnOkv7rMx/vbuzd5IjA=; b=cJe2vQt5VACeXj3hzsSNgc5RCkAEph46QJg6wlGqUbIBUJ7X8dKEkQp2lxGsRB/8fZ b90yyVJrwrqYDzy5gsUtcrFmR5uO3nqv0Y6QctDZpXfdIv5Xk8SfG/Fdk1BwGUpnDYVM YPM/jO6fBrtqsGtsQH25wGszJWxSSoZbPezaPAUL5sIRUi3PEUW+oj7ysRIXK5twHV/d GiCaEQmy/bBYkCF4lAL9bC5VpcDs2ZV4fjiMgRlloQl/DQrrJ3R5l8d1PAK4Qwk3B3Nu w+P4cfNSg+jGHsgGMR5FJ/83G4E2xHePt1f02V/KZK/qWhOABHtoPdpHROZ1uZLMVHD1 xIIA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:from:to:cc:subject:date:message-id; bh=GT4Bk9dT9oL1IWkeLESxHzy5fnOkv7rMx/vbuzd5IjA=; b=MtigBaMK3ONtwlmQWNXtO98LhHfieG6o9xgnOzEFlSbx1HYfT0vltztabLekZH0VQO ETscHOT9ON3uG4CN9X+zM4if1FhAF7tZpcOZijSrWpMdByurOWCNx5WDTSW4K9yxBiEi +PXfE3QOcZXxr15L7JE0nmLISIlwb1M/A3bt5qehXT7Fl0j9tlzu7QGtbfO4zh/Z9JHw X20L7knvUJBUt0dbg1egOa1NwBm+RfIdgri/y7/s9H04Vlo0BJjjcBk2qS2zkFJLBKGB 06uE2C+Drr2sMBdZei9yOYD3MSxwGojuoj4hHNbsMK19tyRjz2iyy4w6IEqDTlPsI2OT sVLQ== X-Gm-Message-State: APjAAAWsDY5nkBHm/yuLPuH6uOfaPmPQd81sVqRlmClWjgRXLZMHZA9s emBqRcgWpr3YRJV9fTVrJww= X-Google-Smtp-Source: APXvYqxCLuXkjUOEkHeMoZ7z9nIev5tNidhjhPgHiaUyDo9Ia490YfKclBXPY6maQF02rFx1+NfRIQ== X-Received: by 2002:a17:902:28e6:: with SMTP id f93mr25356170plb.264.1553521897966; Mon, 25 Mar 2019 06:51:37 -0700 (PDT) Received: from tianyukernel.corp.microsoft.com ([167.220.255.93]) by smtp.googlemail.com with ESMTPSA id k72sm44694562pfb.122.2019.03.25.06.51.33 (version=TLS1_2 cipher=ECDHE-RSA-AES128-SHA bits=128/128); Mon, 25 Mar 2019 06:51:37 -0700 (PDT) From: lantianyu1986@gmail.com X-Google-Original-From: Tianyu.Lan@microsoft.com To: tglx@linutronix.de, mingo@kernel.org, konrad.wilk@oracle.com, jpoimboe@redhat.com, peterz@infraded.org, mojha@codeaurora.org, peterz@infradead.org, jkosina@suse.cz, riel@surriel.com, luto@kernel.org, Tianyu.Lan@microsoft.com, michael.h.kelley@microsoft.com, kys@microsoft.com, gregkh@linuxfoundation.org Cc: linux-kernel@vger.kernel.org, stable@vger.kernel.org Subject: [Fix PATCH] cpu/hotplug: Fix bug report when add "nosmt" parameter with CONFIG_HOTPLUG_CPU=N Date: Mon, 25 Mar 2019 21:51:23 +0800 Message-Id: <1553521883-20868-1-git-send-email-Tianyu.Lan@microsoft.com> X-Mailer: git-send-email 2.7.4 Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Lan Tianyu When add "nosmt" parameter, kernel still boots up all logical cpus once and set CR4.MCE on each CPU. This is to avoid shutting down machine when a broadacasted MCE is observed CR4.MCE=0b. (Detail please see comment in the cpu_smt_allowed()). Smt cpus will bring up and bring down during kernel boot with "nosmt" parameter. When CONFIG_HOTPLUG_CPU=Y, CPU_DYING callbacks will be called inside stop-machine and irq is disabled. This happens in the take_cpu_down() callback. When CONFIG_HOTPLUG_CPU=N,CPU_DYING callbacks will be called with irq enabled. smpcfd_dying_cpu() is one of CPU_DYING callbacks and it assumes to be called when irq is disabled. smpcfd_dying_cpu() calls flush_smp_call_ function_queue() which requires to be called with irq disabled. When CONFIG_HOTPLUG_CPU=N and add "nosmt" parameter, smpcfd_dying_cpu() is called with irq enalbed and this triggers BUG_ON(!irqs_disabled()) in the irq_work_run_list(). This patch is to fix the issue. Fixes: 0cc3cd21657b ("cpu/hotplug: Boot HT siblings at least once") Signed-off-by: Lan Tianyu --- kernel/smp.c | 5 +++++ 1 file changed, 5 insertions(+) diff --git a/kernel/smp.c b/kernel/smp.c index f4cf1b0..33f1970 100644 --- a/kernel/smp.c +++ b/kernel/smp.c @@ -73,6 +73,8 @@ int smpcfd_dead_cpu(unsigned int cpu) int smpcfd_dying_cpu(unsigned int cpu) { + unsigned long flags; + /* * The IPIs for the smp-call-function callbacks queued by other * CPUs might arrive late, either due to hardware latencies or @@ -82,7 +84,10 @@ int smpcfd_dying_cpu(unsigned int cpu) * ensure that the outgoing CPU doesn't go offline with work * still pending. */ + local_irq_save(flags); flush_smp_call_function_queue(false); + local_irq_restore(flags); + return 0; } -- 2.7.4