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_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 6B075C4321D for ; Fri, 24 Aug 2018 12:03:47 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 151E62152B for ; Fri, 24 Aug 2018 12:03:47 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 151E62152B Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=kernel.org 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 S1727682AbeHXPiG (ORCPT ); Fri, 24 Aug 2018 11:38:06 -0400 Received: from mx2.suse.de ([195.135.220.15]:38404 "EHLO mx1.suse.de" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1726513AbeHXPiF (ORCPT ); Fri, 24 Aug 2018 11:38:05 -0400 X-Virus-Scanned: by amavisd-new at test-mx.suse.de Received: from relay1.suse.de (unknown [195.135.220.254]) by mx1.suse.de (Postfix) with ESMTP id 776F8AD65; Fri, 24 Aug 2018 12:03:42 +0000 (UTC) Date: Fri, 24 Aug 2018 14:03:39 +0200 From: Michal Hocko To: christian.koenig@amd.com Cc: kvm@vger.kernel.org, Radim =?utf-8?B?S3LEjW3DocWZ?= , Tetsuo Handa , Joonas Lahtinen , Sudeep Dutt , dri-devel@lists.freedesktop.org, linux-mm@kvack.org, Andrea Arcangeli , "David (ChunMing) Zhou" , Dimitri Sivanich , Jason Gunthorpe , linux-rdma@vger.kernel.org, amd-gfx@lists.freedesktop.org, David Airlie , Doug Ledford , David Rientjes , xen-devel@lists.xenproject.org, intel-gfx@lists.freedesktop.org, Jani Nikula , Leon Romanovsky , =?iso-8859-1?B?Suly9G1l?= Glisse , Rodrigo Vivi , Boris Ostrovsky , Juergen Gross , Mike Marciniszyn , Dennis Dalessandro , LKML , Ashutosh Dixit , Alex Deucher , Paolo Bonzini , Andrew Morton , Felix Kuehling Subject: Re: [PATCH] mm, oom: distinguish blockable mode for mmu notifiers Message-ID: <20180824120339.GL29735@dhcp22.suse.cz> References: <20180716115058.5559-1-mhocko@kernel.org> <8cbfb09f-0c5a-8d43-1f5e-f3ff7612e289@I-love.SAKURA.ne.jp> <20180824113248.GH29735@dhcp22.suse.cz> <20180824115226.GK29735@dhcp22.suse.cz> MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: 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 Fri 24-08-18 13:57:52, Christian König wrote: > Am 24.08.2018 um 13:52 schrieb Michal Hocko: > > On Fri 24-08-18 13:43:16, Christian König wrote: [...] > > > That won't work like this there might be multiple > > > invalidate_range_start()/invalidate_range_end() pairs open at the same time. > > > E.g. the lock might be taken recursively and that is illegal for a > > > rw_semaphore. > > I am not sure I follow. Are you saying that one invalidate_range might > > trigger another one from the same path? > > No, but what can happen is: > > invalidate_range_start(A,B); > invalidate_range_start(C,D); > ... > invalidate_range_end(C,D); > invalidate_range_end(A,B); > > Grabbing the read lock twice would be illegal in this case. I am sorry but I still do not follow. What is the context the two are called from? Can you give me an example. I simply do not see it in the code, mostly because I am not familiar with it. -- Michal Hocko SUSE Labs