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 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 2F52FC433DB for ; Tue, 26 Jan 2021 16:27:43 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id F32812074A for ; Tue, 26 Jan 2021 16:27:42 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2405500AbhAZQ1X (ORCPT ); Tue, 26 Jan 2021 11:27:23 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:42960 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2403906AbhAZQ0n (ORCPT ); Tue, 26 Jan 2021 11:26:43 -0500 Received: from casper.infradead.org (casper.infradead.org [IPv6:2001:8b0:10b:1236::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 6DD5DC0617A7 for ; Tue, 26 Jan 2021 08:26:02 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=casper.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=PJYWXwMWP1LD0/QSSlqke6xEpoOmE1VjNufMYxAn5C8=; b=R3VGehCt+c/X3Wzpdu2MkeZZ+Z UIy+VMXkOAMWilbuzy3PtEnIBal23BmYtaqwzY1WWYarJLmDFKvDcENbDEZ+PCiOHvSZ2sO9cQEEQ +z1oR5rdgMMC1gRXx6CYB2/ClpiXkCTW9xz3hO4VAaBis4Wwh9iH3mbDBRaAJfbEkvo6pQiht4Tkh nw6VAi/UCRRiecZpB9W6CjQ3ozLF/QBOVfI6EzurEeeL6YE5VoBrN5g6EARxGy5IXkR2E0Vil8BG7 EaQQlaBH8IuGqczEy8hXfADsWpF6D5UDLU1YA12kbDhwP+5bCwySiH6OUxJUSnajhB4e846AI0lLX RDsRkuGg==; Received: from j217100.upc-j.chello.nl ([24.132.217.100] helo=noisy.programming.kicks-ass.net) by casper.infradead.org with esmtpsa (Exim 4.94 #2 (Red Hat Linux)) id 1l4R85-005u6O-1C; Tue, 26 Jan 2021 16:24:05 +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 25B573010C8; Tue, 26 Jan 2021 17:23:44 +0100 (CET) Received: by hirez.programming.kicks-ass.net (Postfix, from userid 1000) id 1378F2029059B; Tue, 26 Jan 2021 17:23:44 +0100 (CET) Date: Tue, 26 Jan 2021 17:23:43 +0100 From: Peter Zijlstra To: Sergey Senozhatsky Cc: Qais Yousef , Petr Mladek , Thomas Gleixner , Steven Rostedt , John Ogness , 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> 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 Wed, Jan 27, 2021 at 12:58:33AM +0900, Sergey Senozhatsky wrote: > On (21/01/26 14:59), Qais Yousef wrote: > > # [67628.388606] hrtimer: interrupt took 304720 ns > > [67628.393546] > > [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 > > [67628.393618] #2: ffff8000152aaa60 (console_lock){+.+.}-{0:0}, at: vprintk_emit+0x12c/0x310 > > [67628.393632] #3: ffff8000152aab88 (console_owner){-.-.}-{0:0}, at: console_unlock+0x190/0x6d8 > > Did I miss something? > > printk() is not permitted to sleep/schedule/etc and it never does. > Generally it should be OK to call it from IRQ (module recursion paths). The report is that it is trying to acquire spin_lock() while holding raw_spin_lock(), which is an invalid lock nesting. Note that this is CONFIG_PROVE_RAW_LOCK_NESTING=y which specifically checks for this. On current (mainline) kernel configs this is not yet a problem, but the moment we do land PREEMPT_RT this order will be problematic.