Messages in this thread | | | Subject | Re: [PATCH] powerpc/mm: update arch_{add,remove}_memory() for radix | From | Michael Ellerman <> | Date | Tue, 28 Jun 2016 21:21:05 +1000 |
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On Thu, 2016-06-23 at 14:37 -0500, Reza Arbab wrote: > On Thu, Jun 23, 2016 at 10:47:20PM +0530, 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 ? > > I'm not sure. Maybe it's best if I back up a step and explain what lead > me to this patch. During hotplug, you get > > ... > arch_add_memory > create_section_mapping > htab_bolt_mapping > BUG_ON(!ppc_md.hpte_insert); > > So it seemed to me that I needed a radix equivalent of > create_section_mapping(). > > After some digging, I found hash__vmemmap_create_mapping() and > radix__vmemmap_create_mapping() did what I needed. I did not notice the > #ifdef SPARSEMEM_VMEMMAP around them.
I think that's more by luck than design. The vmemmap routines use mmu_vmemmap_psize which is probably but not definitely the same as mmu_linear_psize.
> Could it be that the functions just need to be renamed > hash__create_mapping()/radix__create_mapping() and moved out of #ifdef > SPARSEMEM_VMEMMAP?
No, you need to use mmu_linear_psize for the hotplug case.
But you can probably factor out a common routine that both cases use, and hide the hash vs radix check in that.
And probably send me a patch to make MEMORY_HOTPLUG depend on !RADIX for v4.7?
cheers
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