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=-3.3 required=3.0 tests=BAYES_00,DKIM_ADSP_CUSTOM_MED, DKIM_INVALID,DKIM_SIGNED,FREEMAIL_FORGED_FROMDOMAIN,FREEMAIL_FROM, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS, URIBL_BLOCKED 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 DC43BC55178 for ; Sun, 25 Oct 2020 20:27:56 +0000 (UTC) Received: from lists.ozlabs.org (lists.ozlabs.org [203.11.71.2]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id E765522284 for ; Sun, 25 Oct 2020 20:27:55 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="signature verification failed" (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="f3NbGeK+" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org E765522284 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=gmail.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=linuxppc-dev-bounces+linuxppc-dev=archiver.kernel.org@lists.ozlabs.org Received: from bilbo.ozlabs.org (lists.ozlabs.org [IPv6:2401:3900:2:1::3]) by lists.ozlabs.org (Postfix) with ESMTP id 4CK8fc5s8dzDqQG for ; Mon, 26 Oct 2020 07:27:52 +1100 (AEDT) Authentication-Results: lists.ozlabs.org; spf=pass (sender SPF authorized) smtp.mailfrom=gmail.com (client-ip=2607:f8b0:4864:20::d43; helo=mail-io1-xd43.google.com; envelope-from=kernelfans@gmail.com; receiver=) Authentication-Results: lists.ozlabs.org; dmarc=pass (p=none dis=none) header.from=gmail.com Authentication-Results: lists.ozlabs.org; dkim=pass (2048-bit key; unprotected) header.d=gmail.com header.i=@gmail.com header.a=rsa-sha256 header.s=20161025 header.b=f3NbGeK+; dkim-atps=neutral Received: from mail-io1-xd43.google.com (mail-io1-xd43.google.com [IPv6:2607:f8b0:4864:20::d43]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits) server-digest SHA256) (No client certificate requested) by lists.ozlabs.org (Postfix) with ESMTPS id 4CJwLM5cpWzDqSt for ; Sun, 25 Oct 2020 22:12:57 +1100 (AEDT) Received: by mail-io1-xd43.google.com with SMTP id b15so6968568iod.13 for ; Sun, 25 Oct 2020 04:12:57 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=mime-version:references:in-reply-to:from:date:message-id:subject:to :cc; bh=TFkX+ZerAmd8hm3G9ObErPm+YgVkEx8CRGWjFIckLIQ=; b=f3NbGeK+6ZtbJFn78qe4TBYAxMxAh1+TJc804ela0OLJTQw2JEKf1SkDA8eVf9brkR mkLQeYkcGVKrjSHSDPcgQfXWRVFBd3xw1z55/3d2QdheAA0lxY+MqSwtS1VWDMkU6gfi POo9W4DMsNEsyMHN8QHjPnd88b/qTMU1mts1m8Y911y/G1rceY85Trw6aiqI3lezE6ex ybrLhG4vEq7vy3JKBwPWAMPRF7h53KM55YZ8Pdu1XY+9KaTq4z8mfpSTzlF0l7fl5UQk qeM8+X0riyiWK+c6Bn5smz3P9q9uSyVC73BxA7j+VYtPw+51XiuQJw2T6feDufCAZBsv xO0w== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to:cc; bh=TFkX+ZerAmd8hm3G9ObErPm+YgVkEx8CRGWjFIckLIQ=; b=jR//p1nez96oaF/IZLskdkSdLO1uw6wKxxp/kJIvN4dDpogxkoxkNTFGkM1F7+r5y6 JwU1F+FICq98tXS1Doohgr1yJncGQbXcPsO3CnhASw78bcPt0OCq5Slrqlo1+7yRP4CI wDkyACjma+prXxSW+gfcfL+INVpyrU0EhLmgIZtS6EmJrucdBN5pKAbDBv5MM5SrFAQm SmyNQUsCpjImjAVgwblj4JAwA4MpYj+Ry1Amt6upEqeb8Xiew9w4j9Wjm5gcifLbS/LM eL1MGvZCLYLMjJr9rIrb9fqrbM20tNYehLjruY8t13vDgxQvOXeDxBwhK3a7pqNM4YDu 1ODw== X-Gm-Message-State: AOAM5328xqOH/8O4d5HEs4BhFWeOmknAzUXS2+b5m6MumAKbWH23aGct S4QW51N9FLYVj5zAX+yJGNc0aZDTkwC4okxzUQ== X-Google-Smtp-Source: ABdhPJyZD9Zz+IOM7rNg+RoAMaAduHW8YbNrNxUEVG0hEHoPcu1GLzdc08/YxotEW1/Ji2X/IlcELqgPdfyTZiD8Hfo= X-Received: by 2002:a6b:8b95:: with SMTP id n143mr7598620iod.36.1603624372449; Sun, 25 Oct 2020 04:12:52 -0700 (PDT) MIME-Version: 1.0 References: <1603346163-21645-1-git-send-email-kernelfans@gmail.com> <871rhq7j1h.fsf@nanos.tec.linutronix.de> In-Reply-To: <871rhq7j1h.fsf@nanos.tec.linutronix.de> From: Pingfan Liu Date: Sun, 25 Oct 2020 19:12:41 +0800 Message-ID: Subject: Re: [PATCH 0/3] warn and suppress irqflood To: Thomas Gleixner Content-Type: text/plain; charset="UTF-8" X-Mailman-Approved-At: Mon, 26 Oct 2020 07:26:15 +1100 X-BeenThere: linuxppc-dev@lists.ozlabs.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Maulik Shah , Petr Mladek , Oliver Neukum , Jonathan Corbet , "Gustavo A. R. Silva" , Peter Zijlstra , Marc Zyngier , Linus Walleij , "Guilherme G. Piccoli" , linux-doc@vger.kernel.org, LKML , Lina Iyer , Jisheng Zhang , Pawan Gupta , Al Viro , Andrew Morton , afzal mohammed , Kexec Mailing List , Mike Kravetz Errors-To: linuxppc-dev-bounces+linuxppc-dev=archiver.kernel.org@lists.ozlabs.org Sender: "Linuxppc-dev" On Thu, Oct 22, 2020 at 4:37 PM Thomas Gleixner wrote: > > On Thu, Oct 22 2020 at 13:56, Pingfan Liu wrote: > > I hit a irqflood bug on powerpc platform, and two years ago, on a x86 platform. > > When the bug happens, the kernel is totally occupies by irq. Currently, there > > may be nothing or just soft lockup warning showed in console. It is better > > to warn users with irq flood info. > > > > In the kdump case, the kernel can move on by suppressing the irq flood. > > You're curing the symptom not the cause and the cure is just magic and > can't work reliably. Yeah, it is magic. But at least, it is better to printk something and alarm users about what happens. With current code, it may show nothing when system hangs. > > Where is that irq flood originated from and why is none of the > mechanisms we have in place to shut it up working? The bug originates from a driver tpm_i2c_nuvoton, which calls i2c-bus driver (i2c-opal.c). After i2c_opal_send_request(), the bug is triggered. But things are complicated by introducing a firmware layer: Skiboot. This software layer hides the detail of manipulating the hardware from Linux. I guess the software logic can not enter a sane state when kernel crashes. Cc Skiboot and ppc64 community to see whether anyone has idea about it. Thanks, Pingfan