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=-2.2 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, 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 4B901C3A5A1 for ; Wed, 28 Aug 2019 14:18:48 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 2957E2189D for ; Wed, 28 Aug 2019 14:18:48 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726952AbfH1OSr (ORCPT ); Wed, 28 Aug 2019 10:18:47 -0400 Received: from mx1.redhat.com ([209.132.183.28]:48864 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726466AbfH1OSq (ORCPT ); Wed, 28 Aug 2019 10:18:46 -0400 Received: from smtp.corp.redhat.com (int-mx04.intmail.prod.int.phx2.redhat.com [10.5.11.14]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id 15783308123B; Wed, 28 Aug 2019 14:18:46 +0000 (UTC) Received: from llong.remote.csb (dhcp-17-160.bos.redhat.com [10.18.17.160]) by smtp.corp.redhat.com (Postfix) with ESMTP id 7DC1335F2; Wed, 28 Aug 2019 14:18:42 +0000 (UTC) Subject: Re: [PATCH v2] fs/proc/page: Skip uninitialized page when iterating page structures To: Michal Hocko Cc: Dan Williams , Alexey Dobriyan , Andrew Morton , linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org, linux-mm@kvack.org, Stephen Rothwell , "Michael S. Tsirkin" , Toshiki Fukasawa References: <20190826124336.8742-1-longman@redhat.com> <20190827142238.GB10223@dhcp22.suse.cz> <20190828080006.GG7386@dhcp22.suse.cz> <8363a4ba-e26f-f88c-21fc-5dd1fe64f646@redhat.com> <20190828140938.GL28313@dhcp22.suse.cz> From: Waiman Long Organization: Red Hat Message-ID: <4367f507-97ba-a74e-6bf5-811cdd6ecdf9@redhat.com> Date: Wed, 28 Aug 2019 10:18:41 -0400 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.7.2 MIME-Version: 1.0 In-Reply-To: <20190828140938.GL28313@dhcp22.suse.cz> Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 7bit Content-Language: en-US X-Scanned-By: MIMEDefang 2.79 on 10.5.11.14 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.49]); Wed, 28 Aug 2019 14:18:46 +0000 (UTC) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 8/28/19 10:09 AM, Michal Hocko wrote: > On Wed 28-08-19 09:46:21, Waiman Long wrote: >> On 8/28/19 4:00 AM, Michal Hocko wrote: >>> On Tue 27-08-19 16:22:38, Michal Hocko wrote: >>>> Dan, isn't this something we have discussed recently? >>> This was http://lkml.kernel.org/r/20190725023100.31141-3-t-fukasawa@vx.jp.nec.com >>> and talked about /proc/kpageflags but this is essentially the same thing >>> AFAIU. I hope we get a consistent solution for both issues. >>> >> Yes, it is the same problem. The uninitialized page structure problem >> affects all the 3 /proc/kpage{cgroup,count,flags) files. >> >> Toshiki's patch seems to fix it just for /proc/kpageflags, though. > Yup. I was arguing that whacking a mole kinda fix is far from good. Dan > had some arguments on why initializing those struct pages is a problem. > The discussion had a half open end though. I hoped that Dan would try > out the initialization side but I migh have misunderstood. If the page structures of the reserved PFNs are always initialized, that will fix the problem too. I am not familiar with the zone device code. So I didn't attempt to do that. Cheers, Longman