From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from psmtp.com (na3sys010amx191.postini.com [74.125.245.191]) by kanga.kvack.org (Postfix) with SMTP id B18716B0002 for ; Tue, 21 May 2013 02:35:11 -0400 (EDT) Message-ID: <519B1641.1020906@cn.fujitsu.com> Date: Tue, 21 May 2013 14:37:53 +0800 From: Tang Chen MIME-Version: 1.0 Subject: Re: [PATCH 2/2 v2, RFC] Driver core: Introduce offline/online callbacks for memory blocks References: <1576321.HU0tZ4cGWk@vostro.rjw.lan> <1583356.7oqZ7gBy2q@vostro.rjw.lan> <2376818.CRj1BTLk0Y@vostro.rjw.lan> <19540491.PRsM4lKIYM@vostro.rjw.lan> In-Reply-To: <19540491.PRsM4lKIYM@vostro.rjw.lan> Content-Transfer-Encoding: 7bit Content-Type: text/plain; charset=UTF-8; format=flowed Sender: owner-linux-mm@kvack.org List-ID: To: "Rafael J. Wysocki" Cc: Greg Kroah-Hartman , Toshi Kani , ACPI Devel Maling List , LKML , isimatu.yasuaki@jp.fujitsu.com, vasilis.liaskovitis@profitbricks.com, Len Brown , linux-mm@kvack.org Hi Rafael, Please see below. On 05/04/2013 07:21 PM, Rafael J. Wysocki wrote: ...... > static BLOCKING_NOTIFIER_HEAD(memory_chain); > @@ -278,33 +283,64 @@ static int __memory_block_change_state(s > { > int ret = 0; > > - if (mem->state != from_state_req) { > - ret = -EINVAL; > - goto out; > - } > + if (mem->state != from_state_req) > + return -EINVAL; > > if (to_state == MEM_OFFLINE) > mem->state = MEM_GOING_OFFLINE; > > ret = memory_block_action(mem->start_section_nr, to_state, online_type); > - > if (ret) { > mem->state = from_state_req; > - goto out; > + } else { > + mem->state = to_state; > + if (to_state == MEM_ONLINE) > + mem->last_online = online_type; Why do we need to remember last online type ? And as far as I know, we can obtain which zone a page was in last time it was onlined by check page->flags, just like online_pages() does. If we use online_kernel or online_movable, the zone boundary will be recalculated. So we don't need to remember the last online type. Seeing from your patch, I guess memory_subsys_online() can only handle online and offline. So mem->last_online is used to remember what user has done through the original way to trigger memory hot-remove, right ? And when user does it in this new way, it just does the same thing as user does last time. But I still think we don't need to remember it because if finally you call online_pages(), it just does the same thing as last time by default. online_pages() { ...... if (online_type == ONLINE_KERNEL ...... if (online_type == ONLINE_MOVABLE...... zone = page_zone(pfn_to_page(pfn)); /* Here, the page will be put into the zone which it belong to last time. */ ...... } I just thought of it. Maybe I missed something in your design. Please tell me if I'm wrong. Reviewed-by: Tang Chen 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