Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754021Ab2KUEgZ (ORCPT ); Tue, 20 Nov 2012 23:36:25 -0500 Received: from cn.fujitsu.com ([222.73.24.84]:44550 "EHLO song.cn.fujitsu.com" rhost-flags-OK-FAIL-OK-OK) by vger.kernel.org with ESMTP id S1752776Ab2KUEgW (ORCPT ); Tue, 20 Nov 2012 23:36:22 -0500 X-IronPort-AV: E=Sophos;i="4.83,290,1352044800"; d="scan'208";a="6243823" Message-ID: <50AC5BC1.9050200@cn.fujitsu.com> Date: Wed, 21 Nov 2012 12:42:41 +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> In-Reply-To: <50AC571C.4030504@gmail.com> X-MIMETrack: Itemize by SMTP Server on mailserver/fnst(Release 8.5.3|September 15, 2011) at 2012/11/21 12:36:03, Serialize by Router on mailserver/fnst(Release 8.5.3|September 15, 2011) at 2012/11/21 12:36:04, Serialize complete at 2012/11/21 12:36:04 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: 4799 Lines: 139 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. > 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? 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. 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/