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 Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by smtp.lore.kernel.org (Postfix) with ESMTP id 7A431C433EF for ; Fri, 14 Jan 2022 10:18:49 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id DA5B66B0072; Fri, 14 Jan 2022 05:18:48 -0500 (EST) Received: by kanga.kvack.org (Postfix, from userid 40) id D55EE6B0073; Fri, 14 Jan 2022 05:18:48 -0500 (EST) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id C1E476B0074; Fri, 14 Jan 2022 05:18:48 -0500 (EST) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0240.hostedemail.com [216.40.44.240]) by kanga.kvack.org (Postfix) with ESMTP id B52F46B0072 for ; Fri, 14 Jan 2022 05:18:48 -0500 (EST) Received: from smtpin27.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay05.hostedemail.com (Postfix) with ESMTP id 673D01809FF19 for ; Fri, 14 Jan 2022 10:18:48 +0000 (UTC) X-FDA: 79028493936.27.7374E5D Received: from smtp-out1.suse.de (smtp-out1.suse.de [195.135.220.28]) by imf05.hostedemail.com (Postfix) with ESMTP id D5E90100008 for ; Fri, 14 Jan 2022 10:18:47 +0000 (UTC) Received: from relay2.suse.de (relay2.suse.de [149.44.160.134]) by smtp-out1.suse.de (Postfix) with ESMTP id A863E21940; Fri, 14 Jan 2022 10:18:46 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=suse.com; s=susede1; t=1642155526; h=from:from:reply-to:date:date:message-id:message-id:to:to:cc:cc: mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=kWddwJSL1o1Vp5zBtOWqmgsbQtzopDy7PEJEHXyvaFA=; b=lFjyX/WQB8eQn8Cx1M1xLjGpIm3TtyamT9rIjr6HViTm/dozNA44nJRPWIfnhKGp7w3c0V A/Q/InTc66rhdHrnCeikgPWyAMUAQeiNbrSliotwPorA0DF2fQpnPLXwT6Q8LaTlOW/Pzl FDfj92IHU9nu4ovRTey66DCwFQ9qGI0= Received: from suse.cz (unknown [10.100.201.86]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by relay2.suse.de (Postfix) with ESMTPS id 12E58A3B8E; Fri, 14 Jan 2022 10:18:46 +0000 (UTC) Date: Fri, 14 Jan 2022 11:18:45 +0100 From: Michal Hocko To: Xiongwei Song Cc: Xiongwei Song , akpm@linux-foundation.org, David Hildenbrand , dan.j.williams@intel.com, osalvador@suse.de, naoya.horiguchi@nec.com, thunder.leizhen@huawei.com, linux-mm@kvack.org, linux-fsdevel@vger.kernel.org, Linux Kernel Mailing List Subject: Re: [PATCH v3 2/2] proc: Add getting pages info of ZONE_DEVICE support Message-ID: References: <20220112143517.262143-1-sxwjean@me.com> <20220112143517.262143-3-sxwjean@me.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: X-Rspamd-Queue-Id: D5E90100008 X-Stat-Signature: ows17hnjppufitzbjhyxws78pxkc39ui Authentication-Results: imf05.hostedemail.com; dkim=pass header.d=suse.com header.s=susede1 header.b="lFjyX/WQ"; dmarc=pass (policy=quarantine) header.from=suse.com; spf=pass (imf05.hostedemail.com: domain of mhocko@suse.com designates 195.135.220.28 as permitted sender) smtp.mailfrom=mhocko@suse.com X-Rspamd-Server: rspam03 X-HE-Tag: 1642155527-114743 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 Fri 14-01-22 18:03:04, Xiongwei Song wrote: > HI Michal, > > On Thu, Jan 13, 2022 at 11:31 PM Michal Hocko wrote: > > > > On Wed 12-01-22 22:35:17, sxwjean@me.com wrote: > > > From: Xiongwei Song > > > > > > When requesting pages info by /proc/kpage*, the pages in ZONE_DEVICE were > > > ignored. > > > > > > The pfn_to_devmap_page() function can help to get page that belongs to > > > ZONE_DEVICE. > > > > Why is this needed? Who would consume that information and what for? > > It's for debug purpose, which checks page flags in system wide. No any other > special thought. But it looks like it's not appropriate to expose now from my > understand, which is from David's comment. > https://lore.kernel.org/linux-mm/20220110141957.259022-1-sxwjean@me.com/T/#m4eccbb2698dbebc80ec00be47382b34b0f64b4fc yes, I do agree with David. This is the reason I am asking because I do remember we have deliberately excluded those pages. If there is no real user to use that information then I do not think we want to make the code more complex and check for memmap and other peculiarities. Thanks! -- Michal Hocko SUSE Labs