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=-5.1 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,FREEMAIL_FORGED_FROMDOMAIN,FREEMAIL_FROM, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE, SPF_PASS,URIBL_BLOCKED,USER_AGENT_SANE_1 autolearn=unavailable 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 2314FC3F68F for ; Thu, 6 Feb 2020 02:26:49 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id EB062214AF for ; Thu, 6 Feb 2020 02:26:48 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="cKFrqDsj" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727662AbgBFC0s (ORCPT ); Wed, 5 Feb 2020 21:26:48 -0500 Received: from mail-wr1-f68.google.com ([209.85.221.68]:38175 "EHLO mail-wr1-f68.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727307AbgBFC0r (ORCPT ); Wed, 5 Feb 2020 21:26:47 -0500 Received: by mail-wr1-f68.google.com with SMTP id y17so5260926wrh.5 for ; Wed, 05 Feb 2020 18:26:46 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=date:from:to:cc:subject:message-id:reply-to:references:mime-version :content-disposition:in-reply-to:user-agent; bh=+zyZWPUkPVNFFY3hh4hIyv4aMVD0rm8A2cdK0RoicIE=; b=cKFrqDsjIr1tl3iYOfd8i5N+6WGzExpQt1zEZE4gvoGS50mQCgSgyZWyjH3eOkzKo9 RDZJ7NGW4fHobWlOyv+mw9wMyrPzJ0l2M/Tr9bUZnsDU3sOw8hSExu6gSVFJ+/naExPa 3j+vXynaLBvNZWqGR5zWPtemWPE/G90t0fdbH08FGxXrjOHcGTcoWb6pVVgAsanK0U1O nNLMye7+70Jq5JwQ1B5n7GC/BSQhlnC+UxpgsGw6P6YeCoCrJiDuqFpIlIV1WQcMupxm OP/bVGVx5o9J10VeIrGC4WNueyE97I5ze8BTnGKxwzLnX+nTIB/Ts+PumcdStVqzFw27 k5Xg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:date:from:to:cc:subject:message-id:reply-to :references:mime-version:content-disposition:in-reply-to:user-agent; bh=+zyZWPUkPVNFFY3hh4hIyv4aMVD0rm8A2cdK0RoicIE=; b=sx0mE0dEllWj32HHHtmLPtSz98y5UfpmyxJSaWEXJqAwpazyeh7c09O5TuLxvTtRq3 3ulyKdWwC7zlI1pTLfUwhDd4Sb3cpwh4cAr830cJ/Cp5iSoqYQeL+4XRLAmXdjLvI6WE eJ8ET+rbnIjfHAUR5v+gfRO3K3wFiVUjDH2lbuItb3CyeHY7EdTegMm3O5vLY1DrVxPT nO+oz9NbyloUY2TsR/n+GoV76BVmY1zRh5r6U2kHwglt1PTyinQC3DqX7Kg8SsNZZ4g2 6mTkVzegztFeppqISW3zvkeIta2y8LtRSG9LCjOg//wU9EujrKGk2e0hPWUE/g8lBXfh Cxvg== X-Gm-Message-State: APjAAAXoDDUDpvxhzLTeA7KvKzr3qeNmWXbUfzi4AaoKc2rEc0Pdp6lO w1LJt2CxAsfHdeRTRPpoC7o= X-Google-Smtp-Source: APXvYqxPkWZV7sd4ISuJQkqpONwJExPC3C4PjxmS7dKJsknBYSqhu5M7+AwEwYv5/9+Y33VJrUXPNg== X-Received: by 2002:a5d:4052:: with SMTP id w18mr707506wrp.112.1580956005652; Wed, 05 Feb 2020 18:26:45 -0800 (PST) Received: from localhost ([185.92.221.13]) by smtp.gmail.com with ESMTPSA id c13sm2396166wrx.9.2020.02.05.18.26.44 (version=TLS1_2 cipher=ECDHE-RSA-CHACHA20-POLY1305 bits=256/256); Wed, 05 Feb 2020 18:26:44 -0800 (PST) Date: Thu, 6 Feb 2020 02:26:44 +0000 From: Wei Yang To: Baoquan He Cc: Wei Yang , David Hildenbrand , linux-kernel@vger.kernel.org, linux-mm@kvack.org, Segher Boessenkool , Andrew Morton , Michal Hocko , Oscar Salvador Subject: Re: [PATCH v1] mm/memory_hotplug: Easier calculation to get pages to next section boundary Message-ID: <20200206022644.6u7pxf7by2w5trmi@master> Reply-To: Wei Yang References: <20200205135251.37488-1-david@redhat.com> <20200205231945.GB28446@richard> <20200205235007.GA28870@richard> <20200206001317.GH8965@MiWiFi-R3L-srv> <20200206003736.GI8965@MiWiFi-R3L-srv> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20200206003736.GI8965@MiWiFi-R3L-srv> User-Agent: NeoMutt/20170113 (1.7.2) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, Feb 06, 2020 at 08:37:36AM +0800, Baoquan He wrote: >On 02/06/20 at 08:13am, Baoquan He wrote: >> On 02/06/20 at 07:50am, Wei Yang wrote: >> > On Thu, Feb 06, 2020 at 07:19:45AM +0800, Wei Yang wrote: >> > >On Wed, Feb 05, 2020 at 02:52:51PM +0100, David Hildenbrand wrote: >> > >>Let's use a calculation that's easier to understand and calculates the >> > >>same result. Reusing existing macros makes this look nicer. >> > >> >> > >>We always want to have the number of pages (> 0) to the next section >> > >>boundary, starting from the current pfn. >> > >> >> > >>Suggested-by: Segher Boessenkool >> > >>Cc: Andrew Morton >> > >>Cc: Michal Hocko >> > >>Cc: Oscar Salvador >> > >>Cc: Baoquan He >> > >>Cc: Wei Yang >> > >>Signed-off-by: David Hildenbrand >> > > >> > >Reviewed-by: Wei Yang >> > > >> > >BTW, I got one question about hotplug size requirement. >> > > >> > >I thought the hotplug range should be section size aligned, while taking a >> > >look into current code function check_hotplug_memory_range() guard the range. >> >> A good question. The current code should be block size aligned. I >> remember in some places we assume each block comprise all the sections. >> Can't imagine one or some of them are half section filled. > >I could be wrong, half filled block may not cause problem. > David must be angry about our flooding the mail list :-) Check the code again, there are two memory range check: * check_hotplug_memory_range(), block/section aligned * check_pfn_span(), subsection aligned The second check, check_pfn_span() in __add_pages(), enable the capability to add a memory range with subsection size. This means hotplug still keeps section alignment. BTW, __add_pages() share the same logic as __remove_pages(). Why not change it too? Do I miss something or I don't have the latest source code? -- Wei Yang Help you, Help me