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,URIBL_BLOCKED,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 3CE56ECE58D for ; Wed, 9 Oct 2019 11:24:30 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id 010A72133F for ; Wed, 9 Oct 2019 11:24:29 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 010A72133F 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 6F1CC8E0005; Wed, 9 Oct 2019 07:24:29 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 67B3D8E0003; Wed, 9 Oct 2019 07:24:29 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 542228E0005; Wed, 9 Oct 2019 07:24:29 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0047.hostedemail.com [216.40.44.47]) by kanga.kvack.org (Postfix) with ESMTP id 2CE578E0003 for ; Wed, 9 Oct 2019 07:24:29 -0400 (EDT) Received: from smtpin15.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay04.hostedemail.com (Postfix) with SMTP id CE5C03D01 for ; Wed, 9 Oct 2019 11:24:28 +0000 (UTC) X-FDA: 76024013016.15.smell23_27063805d2a43 X-HE-Tag: smell23_27063805d2a43 X-Filterd-Recvd-Size: 3026 Received: from mx1.suse.de (mx2.suse.de [195.135.220.15]) by imf09.hostedemail.com (Postfix) with ESMTP for ; Wed, 9 Oct 2019 11:24:28 +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 5C333AF05; Wed, 9 Oct 2019 11:24:26 +0000 (UTC) Date: Wed, 9 Oct 2019 13:24:24 +0200 From: Michal Hocko To: David Hildenbrand Cc: linux-kernel@vger.kernel.org, linux-mm@kvack.org, Qian Cai , Alexey Dobriyan , Naoya Horiguchi , Andrew Morton , Stephen Rothwell , Toshiki Fukasawa , Konstantin Khlebnikov , Mike Rapoport , Anthony Yznaga , Jason Gunthorpe , Dan Williams , Logan Gunthorpe , Ira Weiny , "Aneesh Kumar K.V" , linux-fsdevel@vger.kernel.org Subject: Re: [PATCH v1] mm: Fix access of uninitialized memmaps in fs/proc/page.c Message-ID: <20191009112424.GY6681@dhcp22.suse.cz> References: <20191009091205.11753-1-david@redhat.com> <20191009093756.GV6681@dhcp22.suse.cz> <67aeaacc-d850-5c81-bd17-e95c7f7f75df@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <67aeaacc-d850-5c81-bd17-e95c7f7f75df@redhat.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 12:19:59, David Hildenbrand wrote: [...] > > pfn_to_online_page makes sense because offline pages are not really in a > > defined state. This would be worth a patch of its own. I remember there > > The issue is, once I check for pfn_to_online_page(), these functions > can't handle ZONE_DEVICE at all anymore. Especially in regards to > memory_failure() I don't think this is acceptable. Could you be more specific please? I am not sure I am following. > So while I > (personally) only care about adding pfn_to_online_page() checks, the > in-this-sense-fragile-subsection ZONE_DEVICE implementation requires me > to introduce a temporary check for initialized memmaps. > > > was a discussion about the uninitialized zone device memmaps. It would > > be really good to summarize this discussion in the changelog and > > conclude why the explicit check is really good and what were other > > alternatives considered. > > Yeah, I also expressed my feelings and the issues to be solved by > ZONE_DEVICE people in https://lkml.org/lkml/2019/9/6/114. However, the > discussion stalled and nobody really proposed a solution or followed up. I will try to get back to that discussion but is there any technical reason that prevents any conclusion or it is just stuck on a lack of time of the participants? -- Michal Hocko SUSE Labs