Messages in this thread | | | Date | Tue, 20 Nov 2012 14:58:34 +0800 | From | Jaegeuk Hanse <> | Subject | Re: [PATCH v3 06/12] memory-hotplug: unregister memory section on SPARSEMEM_VMEMMAP |
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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@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, >> >> 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 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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