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@xxxxxxxxxxxxxx> >>>> >>>> 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 <rientjes@xxxxxxxxxx> >>>> CC: Jiang Liu <liuj97@xxxxxxxxx> >>>> CC: Len Brown <len.brown@xxxxxxxxx> >>>> CC: Christoph Lameter <cl@xxxxxxxxx> >>>> Cc: Minchan Kim <minchan.kim@xxxxxxxxx> >>>> CC: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> >>>> CC: KOSAKI Motohiro <kosaki.motohiro@xxxxxxxxxxxxxx> >>>> CC: Wen Congyang <wency@xxxxxxxxxxxxxx> >>>> Signed-off-by: Yasuaki Ishimatsu <isimatu.yasuaki@xxxxxxxxxxxxxx> >>>> --- >>>> 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-acpi" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html