From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751626AbcGRIFr (ORCPT ); Mon, 18 Jul 2016 04:05:47 -0400 Received: from mx2.suse.de ([195.135.220.15]:49005 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751326AbcGRIFp (ORCPT ); Mon, 18 Jul 2016 04:05:45 -0400 Subject: Re: [PATCH 1/2] mem-hotplug: use GFP_HIGHUSER_MOVABLE in, alloc_migrate_target() To: Xishi Qiu , Joonsoo Kim References: <57884EAA.9030603@huawei.com> <20160718055150.GF9460@js1304-P5Q-DELUXE> <578C8C8A.8000007@huawei.com> Cc: David Rientjes , Andrew Morton , Naoya Horiguchi , Linux MM , LKML From: Vlastimil Babka Message-ID: <7ce4a7ac-07aa-6a81-48c2-91c4a9355778@suse.cz> Date: Mon, 18 Jul 2016 10:05:44 +0200 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:45.0) Gecko/20100101 Thunderbird/45.1.1 MIME-Version: 1.0 In-Reply-To: <578C8C8A.8000007@huawei.com> Content-Type: text/plain; charset=windows-1252; format=flowed Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 07/18/2016 10:00 AM, Xishi Qiu wrote: > On 2016/7/18 13:51, Joonsoo Kim wrote: > >> On Fri, Jul 15, 2016 at 10:47:06AM +0800, Xishi Qiu wrote: >>> alloc_migrate_target() is called from migrate_pages(), and the page >>> is always from user space, so we can add __GFP_HIGHMEM directly. >> >> No, all migratable pages are not from user space. For example, >> blockdev file cache has __GFP_MOVABLE and migratable but it has no >> __GFP_HIGHMEM and __GFP_USER. >> > > Hi Joonsoo, > > So the original code "gfp_t gfp_mask = GFP_USER | __GFP_MOVABLE;" > is not correct? It's not incorrect. GFP_USER just specifies some reclaim flags, and may perhaps restrict allocation through __GFP_HARDWALL, where the original page could have been allocated without the restriction. But it doesn't put the place in an unexpected address range, as placing a non-highmem page into highmem could. __GFP_MOVABLE then just controls a heuristic for placement within a zone. >> And, zram's memory isn't GFP_HIGHUSER_MOVABLE but has __GFP_MOVABLE. >> > > Can we distinguish __GFP_MOVABLE or GFP_HIGHUSER_MOVABLE when doing > mem-hotplug? I don't understand the question here, can you rephrase with more detail? Thanks. > Thanks, > Xishi Qiu > >> Thanks. >> >> >> . >> > > > From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-wm0-f72.google.com (mail-wm0-f72.google.com [74.125.82.72]) by kanga.kvack.org (Postfix) with ESMTP id 08A506B0262 for ; Mon, 18 Jul 2016 04:05:46 -0400 (EDT) Received: by mail-wm0-f72.google.com with SMTP id f126so52703862wma.3 for ; Mon, 18 Jul 2016 01:05:45 -0700 (PDT) Received: from mx2.suse.de (mx2.suse.de. [195.135.220.15]) by mx.google.com with ESMTPS id h70si3985929wma.48.2016.07.18.01.05.44 for (version=TLS1 cipher=AES128-SHA bits=128/128); Mon, 18 Jul 2016 01:05:44 -0700 (PDT) Subject: Re: [PATCH 1/2] mem-hotplug: use GFP_HIGHUSER_MOVABLE in, alloc_migrate_target() References: <57884EAA.9030603@huawei.com> <20160718055150.GF9460@js1304-P5Q-DELUXE> <578C8C8A.8000007@huawei.com> From: Vlastimil Babka Message-ID: <7ce4a7ac-07aa-6a81-48c2-91c4a9355778@suse.cz> Date: Mon, 18 Jul 2016 10:05:44 +0200 MIME-Version: 1.0 In-Reply-To: <578C8C8A.8000007@huawei.com> Content-Type: text/plain; charset=windows-1252; format=flowed Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org List-ID: To: Xishi Qiu , Joonsoo Kim Cc: David Rientjes , Andrew Morton , Naoya Horiguchi , Linux MM , LKML On 07/18/2016 10:00 AM, Xishi Qiu wrote: > On 2016/7/18 13:51, Joonsoo Kim wrote: > >> On Fri, Jul 15, 2016 at 10:47:06AM +0800, Xishi Qiu wrote: >>> alloc_migrate_target() is called from migrate_pages(), and the page >>> is always from user space, so we can add __GFP_HIGHMEM directly. >> >> No, all migratable pages are not from user space. For example, >> blockdev file cache has __GFP_MOVABLE and migratable but it has no >> __GFP_HIGHMEM and __GFP_USER. >> > > Hi Joonsoo, > > So the original code "gfp_t gfp_mask = GFP_USER | __GFP_MOVABLE;" > is not correct? It's not incorrect. GFP_USER just specifies some reclaim flags, and may perhaps restrict allocation through __GFP_HARDWALL, where the original page could have been allocated without the restriction. But it doesn't put the place in an unexpected address range, as placing a non-highmem page into highmem could. __GFP_MOVABLE then just controls a heuristic for placement within a zone. >> And, zram's memory isn't GFP_HIGHUSER_MOVABLE but has __GFP_MOVABLE. >> > > Can we distinguish __GFP_MOVABLE or GFP_HIGHUSER_MOVABLE when doing > mem-hotplug? I don't understand the question here, can you rephrase with more detail? Thanks. > Thanks, > Xishi Qiu > >> Thanks. >> >> >> . >> > > > -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org