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=-2.4 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,FREEMAIL_FORGED_FROMDOMAIN,FREEMAIL_FROM, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_PASS,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 31884C43381 for ; Mon, 18 Feb 2019 05:46:56 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id E99BD21479 for ; Mon, 18 Feb 2019 05:46:55 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="B5uN4rKW" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727612AbfBRFqy (ORCPT ); Mon, 18 Feb 2019 00:46:54 -0500 Received: from mail-pf1-f195.google.com ([209.85.210.195]:40687 "EHLO mail-pf1-f195.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725776AbfBRFqy (ORCPT ); Mon, 18 Feb 2019 00:46:54 -0500 Received: by mail-pf1-f195.google.com with SMTP id h1so7965810pfo.7 for ; Sun, 17 Feb 2019 21:46:53 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=date:from:to:cc:subject:message-id:references:mime-version :content-disposition:in-reply-to:user-agent; bh=Yn9hWHB55hBIFTQkiQ7zlHrAL86VOVnr/MNJy6IuYXg=; b=B5uN4rKWQPW7DGKXDkYNcW8cEpsC0UVJ7zkN6sJoZrJupZaysMq15KMTHtMdVaGjvT V0tx1ddKMq/3Mp65pz8n/gcFFIxl2ARKfQNkKhoN6wbQk2xKwfMLZy6YVhWxfdk2DLyP pagAIplMmgFRI7V1BlBnTht6zPMdZ4xY5oOQc8hqEOmlSefi1ID0oCrHPxHD1c/xrP+1 1sTW13leHCV08ulYlJ6ixNvBqRcbRe3V68REntl6CbtsAyv849OCEe0rV5e/CWXUE0ve Ny80BRSE87gtafUYC0Nj2HRl0F9mDeJXHVlgUDPqfhXRaVMfTcph9wtmy3s2L1d8WEWv 4ePQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:date:from:to:cc:subject:message-id:references :mime-version:content-disposition:in-reply-to:user-agent; bh=Yn9hWHB55hBIFTQkiQ7zlHrAL86VOVnr/MNJy6IuYXg=; b=WCRglSyAcLu4fOqeAhsUcWh+sSWQUECei+ZsfnIUG/Aps3B8r9tjdVeLOkc1N4jFjL WDfLlYgKvayGOah9MburQ/27SB3HhAtfaJOHSUoY5qBn6eiTdnZSgF7feVOMHtwYuOXs dzDlfEEYnLahaClczliUxC6FQS43PzAxwXj0WipkJzk6jurDK5IFuqMw8845q+SjPBNw xuh8fqeZkORLAAcaZpy6e/QZiHBqIeihZbSKrHwzGubIk1X02liu8yPud3+5HJudSHi0 l/qhaAZmU2Vq+fcr0B7q8z8rLMGvzv7Qq5e2WcbQ+QAgNnZcbYtSW7nGNgqiXhSBXWVC 88zA== X-Gm-Message-State: AHQUAubC8I7fa6sGGoWC6kMseIwRMFbrJYIkS/XJPDwEsLjDs85dh1xN i19Oi9iABfmsoiPQ+zTvtng= X-Google-Smtp-Source: AHgI3IbWRT4HYgM5zNt5zBd/bvNTJ2b0J17nGNQ29a+qP0sQ24JvxRXvjj5kB/Ips/v3hX/7qTY+Aw== X-Received: by 2002:a62:574d:: with SMTP id l74mr16991972pfb.9.1550468813531; Sun, 17 Feb 2019 21:46:53 -0800 (PST) Received: from localhost ([39.7.51.148]) by smtp.gmail.com with ESMTPSA id 11sm15565331pfh.131.2019.02.17.21.46.51 (version=TLS1_2 cipher=ECDHE-RSA-CHACHA20-POLY1305 bits=256/256); Sun, 17 Feb 2019 21:46:52 -0800 (PST) Date: Mon, 18 Feb 2019 14:46:49 +0900 From: Sergey Senozhatsky To: Yao HongBo Cc: Sergey Senozhatsky , linuxarm@huawei.com, linux-kernel@vger.kernel.org Subject: Re: possible deadlock in console_unlock Message-ID: <20190218054649.GA26686@jagdpanzerIV> References: <20190216072127.GA1945@tigerII.localdomain> <20190216073856.GA9979@tigerII.localdomain> <71b097a7-03c5-8a65-76fa-24312b452b51@huawei.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <71b097a7-03c5-8a65-76fa-24312b452b51@huawei.com> 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 Hi, On (02/16/19 15:59), Yao HongBo wrote: > > GFP_NOWARN is probably the best option for now. Yes, it, maybe, > > will not work for fault-injection cases; but printk_safe approach > > is harder to push for, especially given that printk_safe maybe will > > not even exist in the future. > > I have tried GFP_NOWARN, but the problem still exists. > Only print_safe contexts for tty locks can solve the problem. > My test scenario is falt-injection. Oh, I see. Yes, fault-injection is special. I suspect that this patch series can be helpful then https://lore.kernel.org/lkml/20181016050428.17966-1-sergey.senozhatsky@gmail.com/T/#u but first we need to figure out if printk_safe will stay in the kernel (this will take some time). -ss