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=-9.8 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI, SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,USER_AGENT_GIT autolearn=unavailable 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 D5C24C433E1 for ; Thu, 20 Aug 2020 10:39:51 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id B22A620639 for ; Thu, 20 Aug 2020 10:39:51 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1597919991; bh=An8rfrtl2kc96SZkWhF6Ux9sc4/KRpyOvQhPLtfCEFw=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=ws4bDlrC9KIYFqI27cKOgy37zJ0h6CO+Vj3yq4zrBeF1+3iS7EB69xWZv3cv8j9/J RHLvKa2zvKKt5ZkixPy2X0QXpbuw6a7eMoiH39sA8d4kbqRjrNjUyhw5DH6H2bLmUm UudxIoXrQmIOwlgkr/U9Rn2Ig041s907D6RDfcmU= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1731846AbgHTKjq (ORCPT ); Thu, 20 Aug 2020 06:39:46 -0400 Received: from mail.kernel.org ([198.145.29.99]:39756 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1729358AbgHTKR6 (ORCPT ); Thu, 20 Aug 2020 06:17:58 -0400 Received: from localhost (83-86-89-107.cable.dynamic.v4.ziggo.nl [83.86.89.107]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 3624420738; Thu, 20 Aug 2020 10:17:57 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1597918677; bh=An8rfrtl2kc96SZkWhF6Ux9sc4/KRpyOvQhPLtfCEFw=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=fvLEP49Q4p54o8ATD3QGFiEdFcPVPugvLrybN74ptqbE0RGo96GJOIe43pJac42s9 8OP6+bQx1PAWOlLcE9kB0NV0KrD+vZifyrsr3UXn7k87tts+9XeTimq7ies7gsk+3E Sbr406DIeDBMUS3mYUJVyP75Cg262zxMBjEUPWjo= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, kernel test robot , Thomas Gleixner , Ingo Molnar Subject: [PATCH 4.4 026/149] x86/i8259: Use printk_deferred() to prevent deadlock Date: Thu, 20 Aug 2020 11:21:43 +0200 Message-Id: <20200820092126.988641157@linuxfoundation.org> X-Mailer: git-send-email 2.28.0 In-Reply-To: <20200820092125.688850368@linuxfoundation.org> References: <20200820092125.688850368@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Thomas Gleixner commit bdd65589593edd79b6a12ce86b3b7a7c6dae5208 upstream. 0day reported a possible circular locking dependency: Chain exists of: &irq_desc_lock_class --> console_owner --> &port_lock_key Possible unsafe locking scenario: CPU0 CPU1 ---- ---- lock(&port_lock_key); lock(console_owner); lock(&port_lock_key); lock(&irq_desc_lock_class); The reason for this is a printk() in the i8259 interrupt chip driver which is invoked with the irq descriptor lock held, which reverses the lock operations vs. printk() from arbitrary contexts. Switch the printk() to printk_deferred() to avoid that. Reported-by: kernel test robot Signed-off-by: Thomas Gleixner Signed-off-by: Ingo Molnar Cc: stable@vger.kernel.org Link: https://lore.kernel.org/r/87365abt2v.fsf@nanos.tec.linutronix.de Signed-off-by: Greg Kroah-Hartman --- arch/x86/kernel/i8259.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) --- a/arch/x86/kernel/i8259.c +++ b/arch/x86/kernel/i8259.c @@ -204,7 +204,7 @@ spurious_8259A_irq: * lets ACK and report it. [once per IRQ] */ if (!(spurious_irq_mask & irqmask)) { - printk(KERN_DEBUG + printk_deferred(KERN_DEBUG "spurious 8259A interrupt: IRQ%d.\n", irq); spurious_irq_mask |= irqmask; }