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_PASS,URIBL_BLOCKED, USER_AGENT_MUTT 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 AECD9C4360F for ; Thu, 28 Feb 2019 14:08:20 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 7A64F21850 for ; Thu, 28 Feb 2019 14:08:20 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1551362900; bh=eIjMgN4sh1vRVFSRAPg/6Z2z72hGcjdsuFpnmuK9FRY=; h=Date:From:To:Cc:Subject:References:In-Reply-To:List-ID:From; b=cP2Iiik5mFo0+MshgVPseqyYZrTZEdFYp90IaqlCnekBw85LOD/t+95C1PHo93DyY /kaNsquywh/fl2xWHpsxvq1Y8ZcTkzij1S9kasdVGZ4HK+wQj6cjdsRS/TmsR1KOL8 92d1Vre3EBU1FYNnSQ0hOb52y7cJp8e57FFQl9hU= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1732237AbfB1OIT (ORCPT ); Thu, 28 Feb 2019 09:08:19 -0500 Received: from mx2.suse.de ([195.135.220.15]:44982 "EHLO mx1.suse.de" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1728075AbfB1OIS (ORCPT ); Thu, 28 Feb 2019 09:08:18 -0500 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 7B614ADAA; Thu, 28 Feb 2019 14:08:17 +0000 (UTC) Date: Thu, 28 Feb 2019 15:08:17 +0100 From: Michal Hocko To: Oscar Salvador Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org, david@redhat.com, mike.kravetz@oracle.com Subject: Re: [RFC PATCH] mm,memory_hotplug: Unlock 1GB-hugetlb on x86_64 Message-ID: <20190228140817.GD10588@dhcp22.suse.cz> References: <20190221094212.16906-1-osalvador@suse.de> <20190228092154.GV10588@dhcp22.suse.cz> <20190228094104.wbeaowsx25ckpcc7@d104.suse.de> <20190228095535.GX10588@dhcp22.suse.cz> <20190228101949.qnnzgdhyn6deevnm@d104.suse.de> <20190228121115.GA10588@dhcp22.suse.cz> <20190228133951.outlsq7swhp3nffr@d104.suse.de> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20190228133951.outlsq7swhp3nffr@d104.suse.de> User-Agent: Mutt/1.10.1 (2018-07-13) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu 28-02-19 14:40:54, Oscar Salvador wrote: > On Thu, Feb 28, 2019 at 01:11:15PM +0100, Michal Hocko wrote: > > On Thu 28-02-19 11:19:52, Oscar Salvador wrote: > > > On Thu, Feb 28, 2019 at 10:55:35AM +0100, Michal Hocko wrote: > > > > You seemed to miss my point or I am wrong here. If scan_movable_pages > > > > skips over a hugetlb page then there is nothing to migrate it and it > > > > will stay in the pfn range and the range will not become idle. > > > > > > I might be misunterstanding you, but I am not sure I get you. > > > > > > scan_movable_pages() can either skip or not a hugetlb page. > > > In case it does, pfn will be incremented to skip the whole hugetlb > > > range. > > > If that happens, pfn will hold the next non-hugetlb page. > > > > And as a result the previous hugetlb page doesn't get migrated right? > > What does that mean? Well, the page is still in use and we cannot > > proceed with offlining because the full range is not isolated right? > > I might be clumsy today but I still fail to see the point of concern here. No, it's me who is daft. I have misread the patch and seen that also page_huge_active got removed. Now it makes perfect sense to me because active pages are still handled properly. I will leave the decision whether to split up the patch to you. Acked-by: Michal Hocko and sorry for being dense here. -- Michal Hocko SUSE Labs