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=-2.6 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,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 28BF4C4360C for ; Tue, 8 Oct 2019 10:39:16 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 02D9F206C2 for ; Tue, 8 Oct 2019 10:39:16 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1570531156; bh=gdWIcm/fEQmlP/oJYmxNy/wnrsGTgCCRS51f7LuUMRo=; h=Date:From:To:Cc:Subject:References:In-Reply-To:List-ID:From; b=S4QSOePT3zVjH1RdW7/ZSfXcFeUR7a5JCJUHA0DNllcyQiMwZ+yqA3FTEVzutwzc1 daL554jDhdsyPROyGcQG6n1JQ++YMjidAiDosCvVzfK2chI4PFnogZ2I4rcgiwG7Z4 AcsJJK35AhOUOF5wLiY+BPDvj6jXWJ/Ocv6e5G3k= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729893AbfJHKjP (ORCPT ); Tue, 8 Oct 2019 06:39:15 -0400 Received: from mx2.suse.de ([195.135.220.15]:41300 "EHLO mx1.suse.de" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1730256AbfJHKjK (ORCPT ); Tue, 8 Oct 2019 06:39:10 -0400 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 EB0CFAEAF; Tue, 8 Oct 2019 10:39:08 +0000 (UTC) Date: Tue, 8 Oct 2019 12:39:07 +0200 From: Michal Hocko To: Qian Cai Cc: 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 Subject: Re: [PATCH v2] mm/page_isolation: fix a deadlock with printk() Message-ID: <20191008103907.GE6681@dhcp22.suse.cz> References: <20191008084031.GC6681@dhcp22.suse.cz> <298970BD-529E-4095-8D87-61470ADBDD32@lca.pw> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <298970BD-529E-4095-8D87-61470ADBDD32@lca.pw> User-Agent: Mutt/1.10.1 (2018-07-13) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue 08-10-19 06:04:32, Qian Cai wrote: > > > > On Oct 8, 2019, at 4:40 AM, Michal Hocko wrote: > > > > Does this tip point to a real deadlock or merely a class of lockdep > > false dependencies? > > I lean towards it is a real deadlock given how trivial to generate those lock orders everywhere. Have you actually triggered any real deadlock? With a zone->lock in place it would be pretty clear with hard lockups detected. -- Michal Hocko SUSE Labs