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=-3.9 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI, SPF_HELO_NONE,SPF_PASS autolearn=no 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 8CCE0C4363D for ; Thu, 24 Sep 2020 10:28:37 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 1531323741 for ; Thu, 24 Sep 2020 10:28:37 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=infradead.org header.i=@infradead.org header.b="MUT67gQA" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727424AbgIXK2f (ORCPT ); Thu, 24 Sep 2020 06:28:35 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:48782 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727390AbgIXK2f (ORCPT ); Thu, 24 Sep 2020 06:28:35 -0400 Received: from merlin.infradead.org (merlin.infradead.org [IPv6:2001:8b0:10b:1231::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 36BF3C0613CE for ; Thu, 24 Sep 2020 03:28:35 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=merlin.20170209; h=In-Reply-To:Content-Type:MIME-Version: References:Message-ID:Subject:Cc:To:From:Date:Sender:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description; bh=aXpwPr11MPhd3XZ7JuIbfl5lJouU8jwcHCIWXQAJv38=; b=MUT67gQA83FMmsdvm/INbwTJbX cm+mj+YCfR2XZDuy/kzeKSBzx29zskDlefSCrm0ZZ/XdVXWzSYRGCCCHo78b4LJo9IvXxm/BB3VOW ORXE9B2ZFN1VMbTmJX/Y+Yza5feKbjtYLjr0LAfNAdcqy7l6LlTlxN3FOlPQ7eIcZk575gSoGqcMh cz5c5X5b+WT4sbXjc7UGFV0EJtLqySAJfy5C1nUikHaz/pN3gYQEhQVBGZXtpFI/uIW+5+iQ579gU HW/IN0PcMC8sk9J5Emj85j+6rZAc9dLVGeXkpKQNexDy2WCpl5lXNQ0tqvpW3IleNzzphR2f77ImO VtB+ozzw==; Received: from j217100.upc-j.chello.nl ([24.132.217.100] helo=noisy.programming.kicks-ass.net) by merlin.infradead.org with esmtpsa (Exim 4.92.3 #3 (Red Hat Linux)) id 1kLOUE-0004nj-DT; Thu, 24 Sep 2020 10:28:26 +0000 Received: from hirez.programming.kicks-ass.net (hirez.programming.kicks-ass.net [192.168.1.225]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (Client did not present a certificate) by noisy.programming.kicks-ass.net (Postfix) with ESMTPS id 5A9643007CD; Thu, 24 Sep 2020 12:28:22 +0200 (CEST) Received: by hirez.programming.kicks-ass.net (Postfix, from userid 1000) id 3EBCD202A40A3; Thu, 24 Sep 2020 12:28:22 +0200 (CEST) Date: Thu, 24 Sep 2020 12:28:22 +0200 From: Peter Zijlstra To: Daniel Bristot de Oliveira Cc: x86@kernel.org, Thomas Gleixner , Ingo Molnar , Borislav Petkov , "H. Peter Anvin" , Marc Zyngier , Peter Xu , Andy Lutomirski , Bjorn Helgaas , linux-kernel@vger.kernel.org Subject: Re: [PATCH] x86/irq: Use printk_deferred() on raw_spin_lock() protected sections Message-ID: <20200924102822.GA2628@hirez.programming.kicks-ass.net> References: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, Sep 21, 2020 at 06:22:12PM +0200, Daniel Bristot de Oliveira wrote: > While testing hotplug I got this BUG: > > It was caused by printk() inside a code section protected by a > raw_spin_lock() that ended up calling a serial console that > uses a regular spin_lock(). > > Use the printk_deferred() to avoid calling the serial console > in a raw_spin_lock() protected section. I consider printk_deferred() to be a bug, can't we just wait for the new printk implementation to land so we don't need all this nonsense?