On 11/20/2012 02:55 PM, Wen Congyang wrote:
At 11/20/2012 02:22 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, In order to review this patch, I should dig sparse memory codes in advance. But I have some confuse of codes. Why need encode/decode mem map instead of set mem_map to ms->section_mem_map directly?The memmap is aligned, and the low bits are zero. We store some information in these bits. So we need to encode/decode memmap here.
Hi Congyang,Thanks for you reponse. But I mean why return (unsigned long)(mem_map - (section_nr_to_pfn(pnum))); in function sparse_encode_mem_map, and then return ((struct page *)coded_mem_map) + section_nr_to_pfn(pnum); in funtion sparse_decode_mem_map instead of just store mem_map in ms->section_mep_map directly.
Regards, Jaegeuk
Thanks Wen CongyangRegards, JaegeukCC: 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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