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=-6.8 required=3.0 tests=BAYES_00,DKIM_INVALID, DKIM_SIGNED,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SIGNED_OFF_BY, 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 F130DC433E3 for ; Wed, 29 Jul 2020 08:53:36 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id C7F232084D for ; Wed, 29 Jul 2020 08:53:36 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="signature verification failed" (2048-bit key) header.d=linutronix.de header.i=@linutronix.de header.b="zlonqerR"; dkim=permerror (0-bit key) header.d=linutronix.de header.i=@linutronix.de header.b="/0PcZWm8" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728146AbgG2Ixf (ORCPT ); Wed, 29 Jul 2020 04:53:35 -0400 Received: from Galois.linutronix.de ([193.142.43.55]:40520 "EHLO galois.linutronix.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728060AbgG2Ixb (ORCPT ); Wed, 29 Jul 2020 04:53:31 -0400 From: Thomas Gleixner DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020; t=1596012808; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=0pQaj97fsOJ3H+Osv6qlrM9fYlqURwvN/eVEUt3eeEY=; b=zlonqerRO3EuudUBo4ZqqTjTLmbZL9UAwX4u4O/WFqAcNGnV9/aDOU6RzS7XPqyUDQ+YkM EmU+KftHBBuKtuk4ygsxsulwl0rLRN/dD9hpFRDVvsSdSM1KTt7vNpg0EpsTBf6NEoNkKi TUgS0Fta0+g7CxR/YFu0NXJcg6dAOYjmcfdk31aeBU2JD98HMlLR6T2WxkykaN68HCa6YP QjzbqRJ1viyzep9wygDm9ce6DtOuxwQ25N2AjfSlUbw+LPS9vFv+hPoBP/Sj4CS4/6XaD2 XcSLnlpivUov0Yw0eLtT8ugSDIzS4ARwMacrCLera/EDRujqRb+J5KqpxBff3g== DKIM-Signature: v=1; a=ed25519-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020e; t=1596012808; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=0pQaj97fsOJ3H+Osv6qlrM9fYlqURwvN/eVEUt3eeEY=; b=/0PcZWm8Pxx+OSiaPyt+9k/9V7huKe18t4rblEbA8yB9k9izDz9vPRxKFW2nSw6jpttp/P W86B7FdFEkM6xTCA== To: kernel test robot , Hans de Goede Cc: linux-kernel@vger.kernel.org, LKP , x86@kernel.org Subject: x86/i8259: Use printk_deferred() to prevent deadlock In-Reply-To: <20200728090216.GE23458@shao2-debian> References: <20200728090216.GE23458@shao2-debian> Date: Wed, 29 Jul 2020 10:53:28 +0200 Message-ID: <87365abt2v.fsf@nanos.tec.linutronix.de> MIME-Version: 1.0 Content-Type: text/plain Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 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 Cc: stable@vger.kernel.org --- 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 @@ -207,7 +207,7 @@ static void mask_and_ack_8259A(struct ir * 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; }