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, 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 76270C47404 for ; Wed, 9 Oct 2019 11:24:32 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 46C072133F for ; Wed, 9 Oct 2019 11:24:32 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1570620272; bh=4Fmcfm0KoFdBw5yYG0RqxVWrs++/JYc4VaSHXoV5tes=; h=Date:From:To:Cc:Subject:References:In-Reply-To:List-ID:From; b=j0fJ2XIqHzTBmHDj4/Kd4gzgmzqn5G7/6UJERjVHALTNvDfBKN3WQHddYypfVj2xY nYl+OvRHDSf60xl84u5VxuOIs/SQYsohwzyH5wDL73ZKKlF+oKEyi/8qerQMax//WE 4Fp8BchcsYlSiWg+tHFzQPuT8WZok1pg+Oxdgdsc= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729566AbfJILY2 (ORCPT ); Wed, 9 Oct 2019 07:24:28 -0400 Received: from mx2.suse.de ([195.135.220.15]:37662 "EHLO mx1.suse.de" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1727035AbfJILY2 (ORCPT ); Wed, 9 Oct 2019 07:24:28 -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 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) Sender: linux-fsdevel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-fsdevel@vger.kernel.org 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