From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-pf0-f200.google.com (mail-pf0-f200.google.com [209.85.192.200]) by kanga.kvack.org (Postfix) with ESMTP id F01546B0267 for ; Mon, 18 Jul 2016 04:42:08 -0400 (EDT) Received: by mail-pf0-f200.google.com with SMTP id y134so307275678pfg.1 for ; Mon, 18 Jul 2016 01:42:08 -0700 (PDT) Received: from szxga01-in.huawei.com ([58.251.152.64]) by mx.google.com with ESMTPS id l189si2367460pfl.125.2016.07.18.01.42.06 for (version=TLS1 cipher=AES128-SHA bits=128/128); Mon, 18 Jul 2016 01:42:08 -0700 (PDT) Message-ID: <578C93CF.50509@huawei.com> Date: Mon, 18 Jul 2016 16:31:11 +0800 From: Xishi Qiu MIME-Version: 1.0 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> <7ce4a7ac-07aa-6a81-48c2-91c4a9355778@suse.cz> In-Reply-To: <7ce4a7ac-07aa-6a81-48c2-91c4a9355778@suse.cz> Content-Type: text/plain; charset="windows-1252" Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org List-ID: To: Vlastimil Babka Cc: Joonsoo Kim , David Rientjes , Andrew Morton , Naoya Horiguchi , Linux MM , LKML On 2016/7/18 16:05, Vlastimil Babka wrote: > 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. > Hi Joonsoo, When we do memory offline, and the zone is movable zone, can we use "alloc_pages_node(nid, GFP_HIGHUSER_MOVABLE, 0);" to alloc a new page? the nid is the next node. Thanks, Xishi Qiu >> 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