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=-5.4 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,FREEMAIL_FORGED_FROMDOMAIN,FREEMAIL_FROM, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_PASS, URIBL_BLOCKED,USER_AGENT_MUTT 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 29813C43381 for ; Sat, 16 Feb 2019 07:22:47 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id E44DA222D7 for ; Sat, 16 Feb 2019 07:22:46 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="Isqp5m+q" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726829AbfBPHWp (ORCPT ); Sat, 16 Feb 2019 02:22:45 -0500 Received: from mail-pg1-f195.google.com ([209.85.215.195]:43127 "EHLO mail-pg1-f195.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726149AbfBPHWp (ORCPT ); Sat, 16 Feb 2019 02:22:45 -0500 Received: by mail-pg1-f195.google.com with SMTP id v28so5897893pgk.10 for ; Fri, 15 Feb 2019 23:22:44 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=from:date:to:cc:subject:message-id:references:mime-version :content-disposition:in-reply-to:user-agent; bh=PGwf1K1ul1SssrzyY0oltDyHnTAGA6RBtABDfmX5rW8=; b=Isqp5m+qJU1qQBQpX5sAebfqNBlu1//s2U064HV2svlpCswe/FuUlhz1vI+d8qLH/E nb5KZ/JdTqC7CNnWZWgPzXKGRADRoP8RgdarF2Ws3UhqI2l8MUIbArTdkKjEvq3t8f0O 6LEteJzxyVcVbHUUGapMgHu43yRzm7W637nkIC9u7DvHDfUP7QHtGDlKw/nxRf8vzqQf gHZlFQpPf26JiNneB5l4C56dVNB6uiJB/CWVEVbHlOij38nzgNTYa1CALkH06XMDuQu/ 9qMBnjBixXrkVMijJzCD/P2N7csdbhMlMTlRhB1p10uP5mCrqTeswKf4qkQm0SdkW2UU +8EA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:from:date:to:cc:subject:message-id:references :mime-version:content-disposition:in-reply-to:user-agent; bh=PGwf1K1ul1SssrzyY0oltDyHnTAGA6RBtABDfmX5rW8=; b=mN4VYKbYBmFJ7dHHBOG4MsAAm9iEm0FkR48L3Tx55V2suSoMDXo9TQg3hLiS0lKMaw lp2pTRBEdflchacllLeWwEWsPHMoLHGos+sV5zb6xkMx9EBTXimtV8v0tahWCah2uzkO wN5Crz2/qdMDyhxWsgNKVuR9tT2AdfpdT0hIbI3lZdYna9M/597Hlr9qokqvrw7+sTJT gjAleNOjZjwBcuUjbf4tXpnmJS1H2mRDQ/lPFPrNI9CjynBRlcB2YnyimAGkgOQEM168 0RPxVLnaEAzf2lnegMMvyH8q+azYXO5bm9kwQJBrsvWr4P455emA0N4Ng2pimu26+xJj vu/g== X-Gm-Message-State: AHQUAuacTvCAgyBkFup5soYRpxJCEGgTV6aRriwOdKWBmjU482FqJNjZ oCPq59HjuZdSEKZaHYMQXmw= X-Google-Smtp-Source: AHgI3IaqZ7oGf2JR6gz2iqbmBDojdAKYnr/hLn304utSKAaApKFH4Wl+/lImC5Eoh7QgxaeQbVvDPw== X-Received: by 2002:a62:e086:: with SMTP id d6mr13702294pfm.247.1550301764285; Fri, 15 Feb 2019 23:22:44 -0800 (PST) Received: from localhost ([221.162.103.114]) by smtp.gmail.com with ESMTPSA id d129sm13781684pgc.59.2019.02.15.23.22.42 (version=TLS1_2 cipher=ECDHE-RSA-CHACHA20-POLY1305 bits=256/256); Fri, 15 Feb 2019 23:22:43 -0800 (PST) From: Sergey Senozhatsky X-Google-Original-From: Sergey Senozhatsky Date: Sat, 16 Feb 2019 16:21:27 +0900 To: Yao HongBo Cc: sergey.senozhatsky@gmail.com, linuxarm@huawei.com, linux-kernel@vger.kernel.org Subject: Re: possible deadlock in console_unlock Message-ID: <20190216072127.GA1945@tigerII.localdomain> References: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.11.3 (2019-02-01) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On (02/16/19 14:36), Yao HongBo wrote: > hi, sergey: > > As shown in that link, https://lkml.org/lkml/2018/6/6/397 > > On the linux kernel 5.0-rc6, Syzkaller also hit 'possible deadlock in console_unlock' > bug for several times in my environment. > > This solution fixes things for me. Do you have a plan to submit patches to > solve this problem. > > diff --git a/drivers/tty/tty_buffer.c b/drivers/tty/tty_buffer.c > __printk_safe_enter(); > kmalloc(sizeof(struct tty_buffer) + 2 * size, GFP_ATOMIC); > __printk_safe_exit(); I would probably try the following: --- diff --git a/drivers/tty/tty_buffer.c b/drivers/tty/tty_buffer.c index ec145a59f199..058d004dcbaa 100644 --- a/drivers/tty/tty_buffer.c +++ b/drivers/tty/tty_buffer.c @@ -172,7 +172,8 @@ static struct tty_buffer *tty_buffer_alloc(struct tty_port *port, size_t size) have queued and recycle that ? */ if (atomic_read(&port->buf.mem_used) > port->buf.mem_limit) return NULL; - p = kmalloc(sizeof(struct tty_buffer) + 2 * size, GFP_ATOMIC); + p = kmalloc(sizeof(struct tty_buffer) + 2 * size, + GFP_ATOMIC | __GFP_NOWARN); if (p == NULL) return NULL;