From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-ia0-f179.google.com (mail-ia0-f179.google.com [209.85.210.179]) (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 F0B602C00AA for ; Wed, 21 Nov 2012 15:23:06 +1100 (EST) Received: by mail-ia0-f179.google.com with SMTP id o25so4401935iad.38 for ; Tue, 20 Nov 2012 20:23:03 -0800 (PST) Message-ID: <50AC571C.4030504@gmail.com> Date: Wed, 21 Nov 2012 12:22:52 +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> <50AB669D.3060007@gmail.com> <50AC4505.1000007@cn.fujitsu.com> In-Reply-To: <50AC4505.1000007@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 11/21/2012 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. memblock_remove() __memblock_remove() 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? 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) >>