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=-8.6 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_PASS, T_DKIMWL_WL_MED,URIBL_BLOCKED,USER_IN_DEF_DKIM_WL 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 E44D5C46464 for ; Wed, 8 Aug 2018 02:13:37 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 8395E20834 for ; Wed, 8 Aug 2018 02:13:37 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=google.com header.i=@google.com header.b="KmdEMI7w" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 8395E20834 Authentication-Results: mail.kernel.org; dmarc=fail (p=reject dis=none) header.from=google.com Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726986AbeHHEaw (ORCPT ); Wed, 8 Aug 2018 00:30:52 -0400 Received: from mail-yw1-f65.google.com ([209.85.161.65]:42211 "EHLO mail-yw1-f65.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726158AbeHHEav (ORCPT ); Wed, 8 Aug 2018 00:30:51 -0400 Received: by mail-yw1-f65.google.com with SMTP id y203-v6so462950ywd.9 for ; Tue, 07 Aug 2018 19:13:34 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20161025; h=mime-version:in-reply-to:references:from:date:message-id:subject:to :cc; bh=kmipV8+ifV8XjxfY9m6itWBHn4rWguGOVLGERE0Bl04=; b=KmdEMI7wFqOA8vj22HtlazQ33FMBcgDwJyT8qlgMDNRdoSdAnMpk4ElEendwVWim4z G5cmG2fietz0NMnMTmpiXl+ei9EXS83MC8XtyWZx3YEYwJujV+ZV3q+rNuwOb/rjWXgV PkwrDAWewFwgWndiq4Z56K9TXJM9cKIMBqEUbMbK7KxvyPb6RJKLlGKVql3ROWm7Vqur cWSqX/4qDRLEnXwf4uvPdJEruZ9tKHBAcGlS3mmDUdu6T3mWB2s/zw0YS2WjcX6cH3q0 1VkQXx09g1DrtrFzcZFXjg2xSSjrOXXlYSl+TIdadvWW3dfgG6IripqOvuAiBjg0XcVH bQ2A== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:in-reply-to:references:from:date :message-id:subject:to:cc; bh=kmipV8+ifV8XjxfY9m6itWBHn4rWguGOVLGERE0Bl04=; b=mg8D72VZqUZVK4jdpCE7mj2ZNl55Hyakz5vy560Ia62Itnlj8sHt/MUrUW8r94tDZ1 8J2MmvL/g+fYgkQjmxlxWVZ/v6YEF86g0+X5TLMkXndbqdYYZlTAVBRsyySRs+Paizub t9DJf6tbTbpFBS0u5aFkoIlqNXVcYVJIKI/yShXRZPo91GEBdpesh9Dc3eJ+0vkrCNpA BQ8aLBMvpj0RWVGI197GMD6V/z3sG3neqIne/Y3rlKgeunjvBvAmRDZHsj+QuJS+uHXi 9V3OGPrynE49+awjQARsyEKgxIGKOhQoY1R8YuifFmhIYI4QayjBsEyVh2BCdc0ItvDI ANpA== X-Gm-Message-State: AOUpUlFs1jlJ8J0kWdmumyNpREEED+r8GPc8IQ0vntZHBw0oG3H9pXXX VOPaKzSPky7PwMh2UIswLJKWARKzhM99WPa8hAYIHRG7a7U= X-Google-Smtp-Source: AA+uWPyvOEKK/3FhJFisQbme3HXEEvX1RQAajjgx+yPzXQ4e8ZuaC5OvNIZa+G7biA4j9OQgaOr0HumKpUhOe1QB/mM= X-Received: by 2002:a25:b94c:: with SMTP id s12-v6mr433240ybm.91.1533694413660; Tue, 07 Aug 2018 19:13:33 -0700 (PDT) MIME-Version: 1.0 Received: by 2002:a25:bfce:0:0:0:0:0 with HTTP; Tue, 7 Aug 2018 19:13:32 -0700 (PDT) In-Reply-To: <20180807215522.04114097@vmware.local.home> References: <20180730222423.196630-1-joel@joelfernandes.org> <20180730222423.196630-4-joel@joelfernandes.org> <20180806155058.5ee875f4@gandalf.local.home> <20180806214300.13e63523@gandalf.local.home> <20180807094954.5137972d@gandalf.local.home> <446AE5F2-39E0-46B6-8E0B-207E003DBF20@google.com> <20180807103410.4fe203cb@gandalf.local.home> <20180807110906.3a1b0ac4@gandalf.local.home> <6B9E5DC9-0859-41B4-9B72-A7D85E9EA2AD@google.com> <20180807194515.4e549c1a@gandalf.local.home> <6D0A3FD6-2190-4CC0-A3C0-7B3759E73243@google.com> <20180807204820.50b83c6d@vmware.local.home> <20180807215522.04114097@vmware.local.home> From: Joel Fernandes Date: Tue, 7 Aug 2018 19:13:32 -0700 Message-ID: Subject: Re: [PATCH v12 3/3] tracing: Centralize preemptirq tracepoints and unify their usage To: Steven Rostedt Cc: Joel Fernandes , LKML , "Cc: Android Kernel" , Boqun Feng , Byungchul Park , Ingo Molnar , Masami Hiramatsu , Mathieu Desnoyers , Namhyung Kim , Paul McKenney , Peter Zijlstra , Thomas Glexiner , Tom Zanussi Content-Type: text/plain; charset="UTF-8" Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, Aug 7, 2018 at 6:55 PM, Steven Rostedt wrote: > On Tue, 7 Aug 2018 18:17:42 -0700 > Joel Fernandes wrote: > >> From 6986af946ceb04fc9ddc6d5b45fc559b6807e465 Mon Sep 17 00:00:00 2001 >> From: "Joel Fernandes (Google)" >> Date: Sun, 5 Aug 2018 20:17:41 -0700 >> Subject: [PATCH] tracepoint: Run tracepoints even after CPU is offline >> >> Commit f37755490fe9 ("tracepoints: Do not trace when cpu is offline") >> causes a problem for lockdep using tracepoint code. Once a CPU is >> offline, tracepoints donot get called, however this causes a big problem >> for lockdep probes that need to run so that IRQ annotations are marked >> correctly. >> >> A race is possible where while the CPU is going offline, an interrupt >> can come in and then a lockdep assert causes an annotation warning: >> >> [ 106.551354] IRQs not enabled as expected >> [ 106.551785] WARNING: CPU: 1 PID: 0 at kernel/time/tick-sched.c:982 >> tick_nohz_idle_enter+0x99/0xb0 >> [ 106.552964] Modules linked in: >> [ 106.553299] CPU: 1 PID: 0 Comm: swapper/1 Tainted: G W >> >> We need tracepoints to run as late as possible. This commit fixes the >> issue by removing the cpu_online check in tracepoint code that was >> introduced in the mentioned commit, however we now switch to using SRCU >> for all tracepoints and special handle calling tracepoints from NMI so >> that we don't run into issues that result from using sched-RCU when the >> CPUs are marked to be offline. >> >> Fixes: c3bc8fd637a9 ("tracing: Centralize preemptirq tracepoints and >> unify their usage") >> Reported-by: Masami Hiramatsu >> Signed-off-by: Joel Fernandes (Google) > > > The above change log doesn't look like it matches the NMI patch. > > Can you resend with just the NMI changes? I already handled the cpu > offline ones. Ok, sent with "cpu offline" changes dropped, here it is: https://lore.kernel.org/patchwork/patch/972657/ If you could add your Reported-by to it, that would be great as well. > > But I may still have concerns with this patch. Ok let me know what you think. Thanks! - Joel