Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752190Ab2KUFG2 (ORCPT ); Wed, 21 Nov 2012 00:06:28 -0500 Received: from cn.fujitsu.com ([222.73.24.84]:3589 "EHLO song.cn.fujitsu.com" rhost-flags-OK-FAIL-OK-OK) by vger.kernel.org with ESMTP id S1751049Ab2KUFGW (ORCPT ); Wed, 21 Nov 2012 00:06:22 -0500 X-IronPort-AV: E=Sophos;i="4.83,290,1352044800"; d="scan'208";a="6243955" Message-ID: <50AC62C8.8020500@cn.fujitsu.com> Date: Wed, 21 Nov 2012 13:12:40 +0800 From: Wen Congyang User-Agent: Mozilla/5.0 (X11; U; Linux x86_64; en-US; rv:1.9.1.9) Gecko/20100413 Fedora/3.0.4-2.fc13 Thunderbird/3.0.4 MIME-Version: 1.0 To: Jaegeuk Hanse 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> <50AB669D.3060007@gmail.com> <50AC4505.1000007@cn.fujitsu.com> <50AC571C.4030504@gmail.com> <50AC5BC1.9050200@cn.fujitsu.com> <50AC608F.2020307@gmail.com> In-Reply-To: <50AC608F.2020307@gmail.com> X-MIMETrack: Itemize by SMTP Server on mailserver/fnst(Release 8.5.3|September 15, 2011) at 2012/11/21 13:06:02, Serialize by Router on mailserver/fnst(Release 8.5.3|September 15, 2011) at 2012/11/21 13:06:03, Serialize complete at 2012/11/21 13:06:03 Content-Transfer-Encoding: 7bit Content-Type: text/plain; charset=ISO-8859-1 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 5994 Lines: 164 At 11/21/2012 01:03 PM, Jaegeuk Hanse Wrote: > On 11/21/2012 12:42 PM, Wen Congyang wrote: >> At 11/21/2012 12:22 PM, Jaegeuk Hanse Wrote: >>> On 11/21/2012 11:05 AM, Wen Congyang wrote: >>>> At 11/20/2012 07:16 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, >>>>> >>>>> I have a question about these sparse vmemmap memory related >>>>> patches. Hot >>>>> add memory need allocated vmemmap pages, but this time is allocated by >>>>> buddy system. How can gurantee virtual address is continuous to the >>>>> address allocated before? If not continuous, page_to_pfn and >>>>> pfn_to_page >>>>> can't work correctly. >>>> vmemmap has its virtual address range: >>>> ffffea0000000000 - ffffeaffffffffff (=40 bits) virtual memory map (1TB) >>>> >>>> We allocate memory from buddy system to store struct page, and its >>>> virtual >>>> address isn't in this range. So we should update the page table: >>>> >>>> kmalloc_section_memmap() >>>> sparse_mem_map_populate() >>>> pfn_to_page() // get the virtual address in the vmemmap range >>>> vmemmap_populate() // we update page table here >>>> >>>> When we use vmemmap, page_to_pfn() always returns address in the >>>> vmemmap >>>> range, not the address that kmalloc() returns. So the virtual address >>>> is continuous. >>> Hi Congyang, >>> >>> Another question about memory hotplug. During hot remove memory, it will >>> also call memblock_remove to remove related memblock. >> IIRC, we don't touch memblock when hot-add/hot-remove memory. memblock is >> only used for bootmem allocator. I think it isn't used after booting. > > In IBM pseries servers. > > pseries_remove_memory() > pseries_remove_memblock() > memblock_remove() > > Furthermore, memblock is set to record available memory ranges get from > e820 map(you can check it in memblock_x86_fill()) in x86 case, after > hot-remove memory, this range of memory can't be available, why not > remove them as pseries servers' codes do. Oh, it is powerpc, and I don't read this code. I will check it now. Thanks for pointing it out. Wen Congyang > >>> memblock_remove() >>> __memblock_remove()memory-hotplug: unregister memory >>> section on SPARSEMEM_VMEMMAP >>> >>> memblock_isolate_range() >>> memblock_remove_region() >>> >>> But memblock_isolate_range() only record fully contained regions, >>> regions which are partial overlapped just be splitted instead of record. >>> So these partial overlapped regions can't be removed. Where I miss? >> No, memblock_isolate_range() can deal with partial overlapped region. >> ===================== >> if (rbase < base) { >> /* >> * @rgn intersects from below. Split and continue >> * to process the next region - the new top half. >> */ >> rgn->base = base; >> rgn->size -= base - rbase; >> type->total_size -= base - rbase; >> memblock_insert_region(type, i, rbase, base - rbase, >> memblock_get_region_node(rgn)); >> } else if (rend > end) { >> /* >> * @rgn intersects from above. Split and redo the >> * current region - the new bottom half. >> */ >> rgn->base = end; >> rgn->size -= end - rbase; >> type->total_size -= end - rbase; >> memblock_insert_region(type, i--, rbase, end - rbase, >> memblock_get_region_node(rgn)); >> ===================== >> >> If the region is partial overlapped region, we will split the old >> region into >> two regions. After doing this, it is full contained region now. > > You are right, I misunderstand the codes. > >> >> 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/