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=-10.0 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,URIBL_BLOCKED,USER_AGENT_GIT 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 E8A71C433E1 for ; Mon, 3 Aug 2020 12:42:59 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id BE67B2054F for ; Mon, 3 Aug 2020 12:42:59 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1596458579; bh=+3EfgGtmCKrNepVQ0cjyTDgJi1Grs6bidEQ5QqtEGDA=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=YEnbzrOUzQMumyjbS7SzYzmcpF7A55TmLFAizfDX2iawAq/XzNQ3if/Pnywzkl7Bj BaxLq7AmVHoVF2CZhvl8NiLHh/hjds1I+ZvhD5DZl1Uzo/2/2w0/KVqAx97knxhs8c yTxyFSsJD9PeWRcjvan82067jzQSpEYjGDk45/UA= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727932AbgHCMm6 (ORCPT ); Mon, 3 Aug 2020 08:42:58 -0400 Received: from mail.kernel.org ([198.145.29.99]:57470 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1729046AbgHCMa2 (ORCPT ); Mon, 3 Aug 2020 08:30:28 -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 2DD372054F; Mon, 3 Aug 2020 12:30:25 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1596457826; bh=+3EfgGtmCKrNepVQ0cjyTDgJi1Grs6bidEQ5QqtEGDA=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=0l9nhzv2n4K6u/KdcZ86E+ePxcrT7vhR+oahdV2DtbGz2xbN36DYK/SMNfkwBbZJO i4+yyH8gadtS4y9rQ3Nh0uoFTCRc2fkmST7BtKBkFyGdvrPLFPhHYsFtwXXQqeaiGo xUluiK8W5I3PKxV0Odrq+tFhKUciNB0aX8lFg+hw= 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 5.4 87/90] x86/i8259: Use printk_deferred() to prevent deadlock Date: Mon, 3 Aug 2020 14:19:49 +0200 Message-Id: <20200803121901.795797428@linuxfoundation.org> X-Mailer: git-send-email 2.28.0 In-Reply-To: <20200803121857.546052424@linuxfoundation.org> References: <20200803121857.546052424@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Sender: stable-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: stable@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 @@ -207,7 +207,7 @@ 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; }