Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752877Ab2KTLDq (ORCPT ); Tue, 20 Nov 2012 06:03:46 -0500 Received: from mail-pa0-f46.google.com ([209.85.220.46]:41121 "EHLO mail-pa0-f46.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751122Ab2KTLDm (ORCPT ); Tue, 20 Nov 2012 06:03:42 -0500 Message-ID: <50AB6382.40004@gmail.com> Date: Tue, 20 Nov 2012 19:03:30 +0800 From: Jaegeuk Hanse User-Agent: Mozilla/5.0 (X11; Linux i686; rv:16.0) Gecko/20121028 Thunderbird/16.0.2 MIME-Version: 1.0 To: Wen Congyang CC: Yasuaki Ishimatsu , x86@kernel.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org, linuxppc-dev@lists.ozlabs.org, linux-acpi@vger.kernel.org, linux-s390@vger.kernel.org, linux-sh@vger.kernel.org, linux-ia64@vger.kernel.org, cmetcalf@tilera.com, sparclinux@vger.kernel.org, David Rientjes , Jiang Liu , Len Brown , benh@kernel.crashing.org, paulus@samba.org, Christoph Lameter , Minchan Kim , Andrew Morton , KOSAKI Motohiro , Jianguo Wu Subject: Re: [PATCH v3 06/12] memory-hotplug: unregister memory section on SPARSEMEM_VMEMMAP References: <1351763083-7905-1-git-send-email-wency@cn.fujitsu.com> <1351763083-7905-7-git-send-email-wency@cn.fujitsu.com> <50AB21A4.8050709@gmail.com> <50AB2967.5010302@cn.fujitsu.com> <50AB2A1A.6040606@gmail.com> <50AB4F6D.3050002@cn.fujitsu.com> In-Reply-To: <50AB4F6D.3050002@cn.fujitsu.com> Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 3372 Lines: 95 On 11/20/2012 05:37 PM, Wen Congyang wrote: > At 11/20/2012 02:58 PM, Jaegeuk Hanse Wrote: >> On 11/20/2012 02:55 PM, Wen Congyang wrote: >>> At 11/20/2012 02:22 PM, Jaegeuk Hanse Wrote: >>>> On 11/01/2012 05:44 PM, Wen Congyang wrote: >>>>> From: Yasuaki Ishimatsu >>>>> >>>>> Currently __remove_section for SPARSEMEM_VMEMMAP does nothing. But >>>>> even if >>>>> we use SPARSEMEM_VMEMMAP, we can unregister the memory_section. >>>>> >>>>> So the patch add unregister_memory_section() into __remove_section(). >>>> Hi Yasuaki, >>>> >>>> In order to review this patch, I should dig sparse memory codes in >>>> advance. But I have some confuse of codes. Why need encode/decode mem >>>> map instead of set mem_map to ms->section_mem_map directly? >>> The memmap is aligned, and the low bits are zero. We store some >>> information >>> in these bits. So we need to encode/decode memmap here. >> Hi Congyang, >> >> Thanks for you reponse. But I mean why return (unsigned long)(mem_map - >> (section_nr_to_pfn(pnum))); in function sparse_encode_mem_map, and then >> return ((struct page *)coded_mem_map) + section_nr_to_pfn(pnum); in >> funtion sparse_decode_mem_map instead of just store mem_map in >> ms->section_mep_map directly. > I don't know why. I try to find the reason, but I don't find any > place to use the pfn stored in the mem_map except in the decode > function. Maybe the designer doesn't want us to access the mem_map > directly. It seems that mem_map is per node, but pfn is real pfn. you can check __page_to_pfn. > > Thanks > Wen Congyang > >> Regards, >> Jaegeuk >> >>> Thanks >>> Wen Congyang >>> >>>> Regards, >>>> Jaegeuk >>>> >>>>> CC: David Rientjes >>>>> CC: Jiang Liu >>>>> CC: Len Brown >>>>> CC: Christoph Lameter >>>>> Cc: Minchan Kim >>>>> CC: Andrew Morton >>>>> CC: KOSAKI Motohiro >>>>> CC: Wen Congyang >>>>> Signed-off-by: Yasuaki Ishimatsu >>>>> --- >>>>> mm/memory_hotplug.c | 13 ++++++++----- >>>>> 1 file changed, 8 insertions(+), 5 deletions(-) >>>>> >>>>> diff --git a/mm/memory_hotplug.c b/mm/memory_hotplug.c >>>>> index ca07433..66a79a7 100644 >>>>> --- a/mm/memory_hotplug.c >>>>> +++ b/mm/memory_hotplug.c >>>>> @@ -286,11 +286,14 @@ static int __meminit __add_section(int nid, >>>>> struct zone *zone, >>>>> #ifdef CONFIG_SPARSEMEM_VMEMMAP >>>>> static int __remove_section(struct zone *zone, struct mem_section >>>>> *ms) >>>>> { >>>>> - /* >>>>> - * XXX: Freeing memmap with vmemmap is not implement yet. >>>>> - * This should be removed later. >>>>> - */ >>>>> - return -EBUSY; >>>>> + int ret = -EINVAL; >>>>> + >>>>> + if (!valid_section(ms)) >>>>> + return ret; >>>>> + >>>>> + ret = unregister_memory_section(ms); >>>>> + >>>>> + return ret; >>>>> } >>>>> #else >>>>> static int __remove_section(struct zone *zone, struct mem_section >>>>> *ms) >> -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/