Re: [PATCH] powerpc/mm: update arch_{add,remove}_memory() for radix

From	Balbir Singh <bsingharora@gmail.com>
Newsgroups	linux.kernel
Subject	Re: [PATCH] powerpc/mm: update arch_{add,remove}_memory() for radix
Date	2016-06-24 05:30 +0200
Message-ID	<rNpYB-2GF-1@gated-at.bofh.it> (permalink)
References	<rNfPA-4cB-27@gated-at.bofh.it> <rNgsh-4IF-1@gated-at.bofh.it>
Organization	linux.* mail to news gateway

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On 24/06/16 03:17, Aneesh Kumar K.V wrote:
> Reza Arbab <arbab@linux.vnet.ibm.com> writes:
> 
>> These functions are making direct calls to the hash table APIs,
>> leading to a BUG() on systems using radix.
>>
>> Switch them to the vmemmap_{create,remove}_mapping() wrappers, and
>> move to the __meminit section.
> 
> 
> They are really not the same. They can possibly end up using different
> base page size. Also vmemmap is available only with SPARSEMEM_VMEMMAP
> enabled. Does hotplug depend on sparsemem vmemmap ?

# eventually, we can have this option just 'select SPARSEMEM'
config MEMORY_HOTPLUG
        bool "Allow for memory hot-add"
        depends on SPARSEMEM || X86_64_ACPI_NUMA
        depends on ARCH_ENABLE_MEMORY_HOTPLUG

We depend on sparsemem for sure. vmemmap is just a way of getting the memory
virtually mapped. From the patch perspective, I think we need the equivalent of
just mapping the pages in kernel. The address may differ based on whether vmemmap
is used or not and of-course page_size, 

Balbir Singh

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[PATCH] powerpc/mm: update arch_{add,remove}_memory() for radix Reza Arbab <arbab@linux.vnet.ibm.com> - 2016-06-23 18:40 +0200
  Re: [PATCH] powerpc/mm: update arch_{add,remove}_memory() for radix "Aneesh Kumar K.V" <aneesh.kumar@linux.vnet.ibm.com> - 2016-06-23 19:20 +0200
    Re: [PATCH] powerpc/mm: update arch_{add,remove}_memory() for radix Reza Arbab <arbab@linux.vnet.ibm.com> - 2016-06-23 21:40 +0200
      Re: [PATCH] powerpc/mm: update arch_{add,remove}_memory() for radix Reza Arbab <arbab@linux.vnet.ibm.com> - 2016-06-23 22:00 +0200
      Re: [PATCH] powerpc/mm: update arch_{add,remove}_memory() for radix Michael Ellerman <mpe@ellerman.id.au> - 2016-06-28 13:30 +0200
        Re: [PATCH] powerpc/mm: update arch_{add,remove}_memory() for radix "Aneesh Kumar K.V" <aneesh.kumar@linux.vnet.ibm.com> - 2016-06-28 16:10 +0200
        Re: [PATCH] powerpc/mm: update arch_{add,remove}_memory() for radix Reza Arbab <arbab@linux.vnet.ibm.com> - 2016-06-29 17:50 +0200
    Re: [PATCH] powerpc/mm: update arch_{add,remove}_memory() for radix Balbir Singh <bsingharora@gmail.com> - 2016-06-24 05:30 +0200

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