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=-5.4 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI, SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_AGENT_SANE_1 autolearn=ham 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 E71EDC35247 for ; Thu, 6 Feb 2020 02:48:30 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id 9FD4220661 for ; Thu, 6 Feb 2020 02:48:30 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="cl2cILSI" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 9FD4220661 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=redhat.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=owner-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix) id 3E8496B0003; Wed, 5 Feb 2020 21:48:30 -0500 (EST) Received: by kanga.kvack.org (Postfix, from userid 40) id 399E86B0006; Wed, 5 Feb 2020 21:48:30 -0500 (EST) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 2AF2E6B0007; Wed, 5 Feb 2020 21:48:30 -0500 (EST) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0244.hostedemail.com [216.40.44.244]) by kanga.kvack.org (Postfix) with ESMTP id 10AE06B0003 for ; Wed, 5 Feb 2020 21:48:30 -0500 (EST) Received: from smtpin11.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay05.hostedemail.com (Postfix) with ESMTP id BA72B181AC9B6 for ; Thu, 6 Feb 2020 02:48:29 +0000 (UTC) X-FDA: 76458168738.11.duck85_2d0510e63480b X-HE-Tag: duck85_2d0510e63480b X-Filterd-Recvd-Size: 5108 Received: from us-smtp-delivery-1.mimecast.com (us-smtp-2.mimecast.com [205.139.110.61]) by imf42.hostedemail.com (Postfix) with ESMTP for ; Thu, 6 Feb 2020 02:48:29 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1580957308; h=from:from:reply-to:subject:subject: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=scPthlMCXPeadRfg0S1DOYHQjNbqePUziN1beyiv4iw=; b=cl2cILSIJ4NwXJhY7Dp/37xaX8Z6FPRbsLaTikqYJro6GAH4giholxbFM4A4uFza0//7mQ pGVQnWMquQB6k+ZfahoCj1XBWYekQGIrGRoiZLnPj7+G/TadK3prBh9f9jqxWpqOclXQmo br+iEtZyupJzqvmGV1TWl2AnDW+/oVE= Received: from mimecast-mx01.redhat.com (mimecast-mx01.redhat.com [209.132.183.4]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-322-OdVFOAnnPdmHaHjcIcFyPw-1; Wed, 05 Feb 2020 21:48:24 -0500 X-MC-Unique: OdVFOAnnPdmHaHjcIcFyPw-1 Received: from smtp.corp.redhat.com (int-mx02.intmail.prod.int.phx2.redhat.com [10.5.11.12]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id DD46218AB2C0; Thu, 6 Feb 2020 02:48:22 +0000 (UTC) Received: from localhost (ovpn-12-19.pek2.redhat.com [10.72.12.19]) by smtp.corp.redhat.com (Postfix) with ESMTPS id 8BAD960BF7; Thu, 6 Feb 2020 02:48:19 +0000 (UTC) Date: Thu, 6 Feb 2020 10:48:16 +0800 From: Baoquan He To: Wei Yang 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: <20200206024816.GK8965@MiWiFi-R3L-srv> References: <20200205135251.37488-1-david@redhat.com> <20200205231945.GB28446@richard> <20200205235007.GA28870@richard> <20200206001317.GH8965@MiWiFi-R3L-srv> <20200206003736.GI8965@MiWiFi-R3L-srv> <20200206022644.6u7pxf7by2w5trmi@master> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20200206022644.6u7pxf7by2w5trmi@master> User-Agent: Mutt/1.10.1 (2018-07-13) X-Scanned-By: MIMEDefang 2.79 on 10.5.11.12 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 02/06/20 at 02:26am, Wei Yang wrote: > 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 :-) Believe he won't, :-) If you like, we can talk off line. > > 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. memremap_pages() also call add_pages(), it doesn't have the check_hotplug_memory_range() invocation. check_pfn_span() is made for it specifically. > > 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? Good question, and I think it need. Just David is refactoring/cleaning up the remove_pages() code path, this is found out by Segher from patch reviewing.