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=-5.8 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,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 3E1EBC433E6 for ; Tue, 26 Jan 2021 16:21:44 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 0BE572074A for ; Tue, 26 Jan 2021 16:21:44 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2392851AbhAZQVe (ORCPT ); Tue, 26 Jan 2021 11:21:34 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:41442 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2392769AbhAZQTt (ORCPT ); Tue, 26 Jan 2021 11:19:49 -0500 Received: from merlin.infradead.org (merlin.infradead.org [IPv6:2001:8b0:10b:1231::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 374E2C0617A7 for ; Tue, 26 Jan 2021 08:19:09 -0800 (PST) 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=bTVvC5dBR5FLlE9aUyJVC2BZBj2HyB/7vwwlQxUnBck=; b=C5keJZV7t+vZnW8XTMdFqGzzfn MVc5vqicYyZPKSy4dENoX77LyL3g3KjXZKd5IVEmEPUwwPLrQ8o2bvOQRW++UxJ4AzAFhpGyD8cCz gt/jNNPVkdtsYeuSRoqWTaimij6c/k3vzpEriSMovk4d78bobHpvRFW7VyYmI3VQoMP+n+u2gv9LG 2PgZXzyM7CI46JEzMc+pYIBZoh1eGfFglfECV2US9ZQWBv8IsHdl1zaZJFVQFt3g2OfvCk7NfOI4y 1APsxeqTel7ylYt8TlozliWM+u25T4/gevo40zgxFrKjlvVeLLkku2vRF+Ko8NRYmxVSFigcZP59n TFO51hUQ==; 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 1l4R3V-0000lO-0F; Tue, 26 Jan 2021 16:19:01 +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 79CC13019CE; Tue, 26 Jan 2021 17:18:59 +0100 (CET) Received: by hirez.programming.kicks-ass.net (Postfix, from userid 1000) id 46C002C538ED8; Tue, 26 Jan 2021 17:18:59 +0100 (CET) Date: Tue, 26 Jan 2021 17:18:59 +0100 From: Peter Zijlstra To: John Ogness Cc: Qais Yousef , Sergey Senozhatsky , Petr Mladek , Thomas Gleixner , Steven Rostedt , linux-kernel@vger.kernel.org Subject: Re: [PATCH 0/2] Fix BUG: Invalid wait context in hrtimer_interrupt() Message-ID: References: <20210123233741.3614408-1-qais.yousef@arm.com> <20210126145917.r64vzibgpiwyuake@e107158-lin> <874kj3lo3h.fsf@jogness.linutronix.de> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <874kj3lo3h.fsf@jogness.linutronix.de> Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, Jan 26, 2021 at 04:28:42PM +0106, John Ogness wrote: > On 2021-01-26, Qais Yousef wrote: > > [67628.393550] ============================= > > [67628.393554] [ BUG: Invalid wait context ] > > [67628.393557] 5.11.0-rc3-00019-g86be331946f7 #37 Not tainted > > [67628.393560] ----------------------------- > > [67628.393563] sugov:0/192 is trying to lock: > > [67628.393566] ffff000800b1d898 (&port_lock_key){-.-.}-{3:3}, at: pl011_console_write+0x138/0x218 > > [67628.393581] other info that might help us debug this: > > [67628.393584] context-{2:2} > > [67628.393586] 4 locks held by sugov:0/192: > > [67628.393589] #0: ffff0008059cb720 (&sg_policy->work_lock){+.+.}-{4:4}, at: sugov_work+0x58/0x88 > > [67628.393603] #1: ffff800015446f20 (prepare_lock){+.+.}-{4:4}, at: clk_prepare_lock+0x34/0xb0 > pl011_console_write() does: > > local_irq_save(flags); > spin_lock(&uap->port.lock); > > This needs to be: > > spin_lock_irqsave(&uap->port.lock, flags); > > Of course, it will be a trickier than that because of the > @oops_in_progress madness. This bug has been around for quite a while. Well yes, but that's not going to be fixing anything. The problem is that sugov_work() is holding a raw_spin_lock, and you're trying to acquire a spin_lock. That's an invalid lock nesting.