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=-0.6 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 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 91AA7C433EF for ; Tue, 19 Jun 2018 08:08:25 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 4B73320874 for ; Tue, 19 Jun 2018 08:08:25 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="M5Lheezb" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 4B73320874 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=gmail.com Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756405AbeFSIIV (ORCPT ); Tue, 19 Jun 2018 04:08:21 -0400 Received: from mail-pf0-f180.google.com ([209.85.192.180]:45783 "EHLO mail-pf0-f180.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756342AbeFSIIR (ORCPT ); Tue, 19 Jun 2018 04:08:17 -0400 Received: by mail-pf0-f180.google.com with SMTP id a22-v6so9527256pfo.12; Tue, 19 Jun 2018 01:08:16 -0700 (PDT) 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=i0bIMyqo9J/Ty9YANdAtmQsM5kC0e+H571I4dWZ6GYA=; b=M5LheezbnEDPQFGrQLv8IRhIMJHiGU/kZHmU3pqUuOO4gFGONWmtubwcbvOFijWC/9 d7qcUSucZedN/gAUpNQztMdHllAL4G9cxGYH8YgsWznEtHzcOyLeBB8tP9v8J+OKmU9Z oMQgnZcpxbey+OZGEVZE8yV+VjqJo46WEsbq5Ji///oie+ywDwbBqp26qVVKWOg4srsl b0/CTtMS1LIntUiMNb9iOf9skB0I7zmd+ixnBPFgH+O4A0J3xpALrHuBmRxmGma6KRs1 +wucstc2iYl4FmOBoTItSFRbjDrkQ/B2L/ek8j8aGWg3huw8KauOYmxwxgvJyYGJg8nN WBLQ== 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=i0bIMyqo9J/Ty9YANdAtmQsM5kC0e+H571I4dWZ6GYA=; b=I+zD/wbcldd3XCeD3qWBZZnfVnzT6i8Ths8GYnYBdE1RdgJmvc8qbMWu2OS80FH4iW zaT8C4NkFxn9pbNGrbcJRosmDH1UkvVHh2J5z9T0ofHdnoMFbh2jV4vaZw+0KiGYKRlA scmSlG/+UAy4G4PhKBulBU8ZUl7dXA5X2art1AznJb5NbJjd4Os2EitNGn2IWbsLppyv PL/YClV5nucbaWst+Jcqrb2Knf+lA4OR+Up7nP7Xc8xCE+HCpmnEInNL1B4u9OEPy9LS IFhbPb2w1/uW1jwnS7s9z1XnYwgpdZtpcLeK0ciydpk99B/glvKfr786utm6HL4mSFVU rNIQ== X-Gm-Message-State: APt69E04j13YQORjxhoGb4udeYnIJCFKZBY5p2wpnJiy2PzQMg8exVKc PlCEDUsyijtUzrseuxe3kyY= X-Google-Smtp-Source: ADUXVKJf4cAk2fkMZXd9U0X1o4Vpz4TxmJnN4OOyINPZSwXTzAD+1chXnyL9J8Zik8e7y/x01BMuSw== X-Received: by 2002:a62:9513:: with SMTP id p19-v6mr16998117pfd.239.1529395696495; Tue, 19 Jun 2018 01:08:16 -0700 (PDT) Received: from localhost ([175.223.26.106]) by smtp.gmail.com with ESMTPSA id j3-v6sm20890357pgp.47.2018.06.19.01.08.14 (version=TLS1_2 cipher=ECDHE-RSA-CHACHA20-POLY1305 bits=256/256); Tue, 19 Jun 2018 01:08:15 -0700 (PDT) Date: Tue, 19 Jun 2018 17:08:12 +0900 From: Sergey Senozhatsky To: Petr Mladek Cc: Sergey Senozhatsky , Sergey Senozhatsky , syzbot , linux-kernel@vger.kernel.org, rostedt@goodmis.org, syzkaller-bugs@googlegroups.com, Greg Kroah-Hartman , Jiri Slaby , linux-serial@vger.kernel.org, Andrew Morton Subject: Re: possible deadlock in console_unlock Message-ID: <20180619080812.GC405@jagdpanzerIV> References: <00000000000087008b056df8fbb3@google.com> <20180607051019.GA10406@jagdpanzerIV> <20180607110034.qrkencwsr4stv6xp@pathway.suse.cz> <20180607140100.GA398@tigerII.localdomain> <20180608081855.ctqakvwmg27aydby@pathway.suse.cz> <20180615083804.GB8964@jagdpanzerIV> <20180619080412.zkdanx6bmq5qm3dz@pathway.suse.cz> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20180619080412.zkdanx6bmq5qm3dz@pathway.suse.cz> User-Agent: Mutt/1.10.0 (2018-05-17) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On (06/19/18 10:04), Petr Mladek wrote: > > > > > > We could allow nesting. It is just a matter of how many bits we > > > reserve for it in printk_context variable. > > [..] > > > In each case, I would like to keep the printk_safe context usage > > > at minimum. It has its own problems caused by limited per-cpu buffers > > > and the need to flush them. > > > > May be. Every new printk_safe flavour comes with increasing memory > > usage. > > This must be a misunderstanding. My intention was to introduce > printk_deferred() context. Where any printk() called in this > context would behave like printk_deferred(). It does not need > any extra buffers. Ah, got it. Yes, this can work. -ss