From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-da0-f51.google.com (mail-da0-f51.google.com [209.85.210.51]) (using TLSv1 with cipher ECDHE-RSA-RC4-SHA (128/128 bits)) (Client CN "smtp.gmail.com", Issuer "Google Internet Authority" (not verified)) by ozlabs.org (Postfix) with ESMTPS id 506AB2C0040 for ; Tue, 20 Nov 2012 22:03:44 +1100 (EST) Received: by mail-da0-f51.google.com with SMTP id i30so865299dad.38 for ; Tue, 20 Nov 2012 03:03:42 -0800 (PST) Message-ID: <50AB6382.40004@gmail.com> Date: Tue, 20 Nov 2012 19:03:30 +0800 From: Jaegeuk Hanse MIME-Version: 1.0 To: Wen Congyang 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 Cc: linux-s390@vger.kernel.org, linux-ia64@vger.kernel.org, Len Brown , linux-acpi@vger.kernel.org, linux-sh@vger.kernel.org, x86@kernel.org, linux-kernel@vger.kernel.org, cmetcalf@tilera.com, Jianguo Wu , linux-mm@kvack.org, Yasuaki Ishimatsu , paulus@samba.org, Minchan Kim , KOSAKI Motohiro , David Rientjes , sparclinux@vger.kernel.org, Christoph Lameter , linuxppc-dev@lists.ozlabs.org, Andrew Morton , Jiang Liu List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , 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) >>