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=-2.5 required=3.0 tests=MAILING_LIST_MULTI, SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_1 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 2B189ECE58D for ; Wed, 9 Oct 2019 14:26:26 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id ECC0F20B7C for ; Wed, 9 Oct 2019 14:26:25 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org ECC0F20B7C Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=kernel.org Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=owner-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix) id A11838E0005; Wed, 9 Oct 2019 10:26:25 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 9C2948E0003; Wed, 9 Oct 2019 10:26:25 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 8B1F38E0005; Wed, 9 Oct 2019 10:26:25 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0036.hostedemail.com [216.40.44.36]) by kanga.kvack.org (Postfix) with ESMTP id 6CACA8E0003 for ; Wed, 9 Oct 2019 10:26:25 -0400 (EDT) Received: from smtpin05.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay05.hostedemail.com (Postfix) with SMTP id 12BBE181AC9B4 for ; Wed, 9 Oct 2019 14:26:25 +0000 (UTC) X-FDA: 76024471530.05.egg34_1ae237c12a416 X-HE-Tag: egg34_1ae237c12a416 X-Filterd-Recvd-Size: 2255 Received: from mx1.suse.de (mx2.suse.de [195.135.220.15]) by imf30.hostedemail.com (Postfix) with ESMTP for ; Wed, 9 Oct 2019 14:26:24 +0000 (UTC) X-Virus-Scanned: by amavisd-new at test-mx.suse.de Received: from relay2.suse.de (unknown [195.135.220.254]) by mx1.suse.de (Postfix) with ESMTP id 7364CAD2C; Wed, 9 Oct 2019 14:26:23 +0000 (UTC) Date: Wed, 9 Oct 2019 16:26:23 +0200 From: Michal Hocko To: Peter Oberparleiter Cc: Qian Cai , Christian Borntraeger , Petr Mladek , akpm@linux-foundation.org, sergey.senozhatsky.work@gmail.com, rostedt@goodmis.org, peterz@infradead.org, linux-mm@kvack.org, john.ogness@linutronix.de, david@redhat.com, linux-kernel@vger.kernel.org, Heiko Carstens , Vasily Gorbik Subject: Re: [PATCH v2] mm/page_isolation: fix a deadlock with printk() Message-ID: <20191009142623.GE6681@dhcp22.suse.cz> References: <1570228005-24979-1-git-send-email-cai@lca.pw> <20191007143002.l37bt2lzqtnqjqxu@pathway.suse.cz> <20191007144937.GO2381@dhcp22.suse.cz> <20191008074357.f33f6pbs4cw5majk@pathway.suse.cz> <20191008082752.GB6681@dhcp22.suse.cz> <1570550917.5576.303.camel@lca.pw> <1157b3ae-006e-5b8e-71f0-883918992ecc@linux.ibm.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1157b3ae-006e-5b8e-71f0-883918992ecc@linux.ibm.com> User-Agent: Mutt/1.10.1 (2018-07-13) X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: On Wed 09-10-19 15:56:32, Peter Oberparleiter wrote: [...] > A generic solution would be preferable from my point of view though, > because otherwise each console driver owner would need to ensure that any > lock taken in their console.write implementation is never held while > memory is allocated/released. Considering that console.write is called from essentially arbitrary code path IIUC then all the locks used in this path should be pretty much tail locks or console internal ones without external dependencies. Otherwise we are in a whack a mole situation chasing very complex lock chains. -- Michal Hocko SUSE Labs