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=-2.1 required=3.0 tests=DKIM_SIGNED, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_PASS,T_DKIM_INVALID, USER_AGENT_MUTT 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 39A8BC43334 for ; Thu, 6 Sep 2018 12:56:43 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id E83AA20844 for ; Thu, 6 Sep 2018 12:56:42 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="signature verification failed" (2048-bit key) header.d=infradead.org header.i=@infradead.org header.b="26JkJPe/" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org E83AA20844 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=infradead.org 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 S1728711AbeIFRcD (ORCPT ); Thu, 6 Sep 2018 13:32:03 -0400 Received: from merlin.infradead.org ([205.233.59.134]:44896 "EHLO merlin.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727785AbeIFRcD (ORCPT ); Thu, 6 Sep 2018 13:32:03 -0400 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:Resent-Date: Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Id: List-Help:List-Unsubscribe:List-Subscribe:List-Post:List-Owner:List-Archive; bh=vNBcT9Tk9g5QhVj6Cf6Vh/U2nJjh2M2XFL0k4EV5HTo=; b=26JkJPe/gkG4gGlqQe2khzEbP /p3P0UaZcOECiYnKbO1ZZl2SbjK5YFJjbnOVxS0b0TNGLxwDpCZtiFn4RW1+afYLw9EXecOefmeKI A5D9Sct/dRCCQMQTvHoEUALzwHLyOBz307A8DxzKAlUOglSnxY0kgVK+Lbc3zZZiqhxoEWdoNSTmh Ti4r1SeQKn6ya/GurMBtquujPHbBnLObOmd2wz+k3/sI9wgkBCkQXdkKmfJmVV3gKacCaNixCKNr5 62AdaGMgvXu2eBpYkfNk+4nW01z6/h+ZWZqsCxBcZ+yVvtkD6fYmyXSWETQ9p2Ejx2ghEHJjx1Kco t9jRx+Cpg==; Received: from j217100.upc-j.chello.nl ([24.132.217.100] helo=hirez.programming.kicks-ass.net) by merlin.infradead.org with esmtpsa (Exim 4.90_1 #2 (Red Hat Linux)) id 1fxtpu-0002QS-S3; Thu, 06 Sep 2018 12:56:39 +0000 Received: by hirez.programming.kicks-ass.net (Postfix, from userid 1000) id 8A1F220210301; Thu, 6 Sep 2018 14:56:37 +0200 (CEST) Date: Thu, 6 Sep 2018 14:56:37 +0200 From: Peter Zijlstra To: Niklas Cassel Cc: linux-kernel@vger.kernel.org, bjorn.andersson@linaro.org Subject: Re: stop_machine() soft lockup Message-ID: <20180906125637.GJ24082@hirez.programming.kicks-ass.net> References: <20180904190322.GA21835@centauri.lan> <20180905084241.GS24082@hirez.programming.kicks-ass.net> <20180905114749.GA5345@centauri.lan> <20180905131410.GY24082@hirez.programming.kicks-ass.net> <20180905134553.GB5345@centauri.lan> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20180905134553.GB5345@centauri.lan> User-Agent: Mutt/1.10.0 (2018-05-17) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, Sep 05, 2018 at 03:45:53PM +0200, Niklas Cassel wrote: > However, I just managed to get this lockdep splat when booting without > earlycon and ftrace=irqsoff > I'm not sure that it is related, but I'm planning on looking into it anyway: That looks like your generic printk is crap splat. I tend to use this patch-set: https://lkml.kernel.org/r/20170928121823.430053219@infradead.org and have (on x86): earlyprintk=serial,ttyS0,115200 force_early_printk debug ignore_loglevel That results in a printk that does pure UART bit-banging and works from any context without issue.