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@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.
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@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)
--
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