Messages in this thread | | | Date | Wed, 21 Nov 2012 13:03:11 +0800 | From | Jaegeuk Hanse <> | Subject | Re: [PATCH v3 06/12] memory-hotplug: unregister memory section on SPARSEMEM_VMEMMAP |
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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 <isimatu.yasuaki@jp.fujitsu.com> >>>>> >>>>> 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.
>> 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 <rientjes@google.com> >>>>> CC: Jiang Liu <liuj97@gmail.com> >>>>> CC: Len Brown <len.brown@intel.com> >>>>> CC: Christoph Lameter <cl@linux.com> >>>>> Cc: Minchan Kim <minchan.kim@gmail.com> >>>>> CC: Andrew Morton <akpm@linux-foundation.org> >>>>> CC: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> >>>>> CC: Wen Congyang <wency@cn.fujitsu.com> >>>>> Signed-off-by: Yasuaki Ishimatsu <isimatu.yasuaki@jp.fujitsu.com> >>>>> --- >>>>> 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) >>
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