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SubjectRe: [PATCH v2 08/23] mm/memblock: Add memblock memory allocation apis
Hi Tejun,

On 12/04/2013 01:24 AM, Tejun Heo wrote:
> Hello,
>
> On Mon, Dec 02, 2013 at 09:27:23PM -0500, Santosh Shilimkar wrote:
>> So we add equivalent APIs so that we can replace usage of bootmem
>> with memblock interfaces. Architectures already converted to NO_BOOTMEM
>> use these new interfaces and other which still uses bootmem, these new
>> APIs just fallback to exiting bootmem APIs. So no functional change as
>> such.
>
> The last part of the second last sentence doesn't parse too well. I
> think it'd be worthwhile to improve and preferably expand on it as
> this is a bit tricky to understand given the twisted state of early
> memory allocation.
>
>> In long run, once all the achitectures moves to NO_BOOTMEM, we can get rid of
>> bootmem layer completely. This is one step to remove the core code dependency
>> with bootmem and also gives path for architectures to move away from bootmem.
>
> Lines too long?
>

[...]

>
>> +/* FIXME: Move to memblock.h at a point where we remove nobootmem.c */
>> +void *memblock_virt_alloc_try_nid_nopanic(phys_addr_t size,
>> + phys_addr_t align, phys_addr_t from,
>> + phys_addr_t max_addr, int nid);
>
> Wouldn't @min_addr instead of @from make more sense? Ditto for other
> occurrences.
>
>> +void *memblock_virt_alloc_try_nid(phys_addr_t size, phys_addr_t align,
>> + phys_addr_t from, phys_addr_t max_addr, int nid);
>> +void __memblock_free_early(phys_addr_t base, phys_addr_t size);
>> +void __memblock_free_late(phys_addr_t base, phys_addr_t size);
>> +
>> +#define memblock_virt_alloc(x) \
>> + memblock_virt_alloc_try_nid(x, SMP_CACHE_BYTES, BOOTMEM_LOW_LIMIT, \
>> + BOOTMEM_ALLOC_ACCESSIBLE, MAX_NUMNODES)
>
> The underlying function interprets 0 as the default align, so it
> probably is a better idea to just use 0 here.
>
>> +#define memblock_virt_alloc_align(x, align) \
>> + memblock_virt_alloc_try_nid(x, align, BOOTMEM_LOW_LIMIT, \
>> + BOOTMEM_ALLOC_ACCESSIBLE, MAX_NUMNODES)
>
> Also, do we really need this align variant separate when the caller
> can simply specify 0 for the default?

Unfortunately Yes.
We need it to keep compatibility with bootmem/nobootmem
which don't handle 0 as default align value.

>
>> +#define memblock_virt_alloc_nopanic(x) \
>> + memblock_virt_alloc_try_nid_nopanic(x, SMP_CACHE_BYTES, \
>> + BOOTMEM_LOW_LIMIT, \
>> + BOOTMEM_ALLOC_ACCESSIBLE, \
>> + MAX_NUMNODES)
>> +#define memblock_virt_alloc_align_nopanic(x, align) \
>> + memblock_virt_alloc_try_nid_nopanic(x, align, \
>> + BOOTMEM_LOW_LIMIT, \
>> + BOOTMEM_ALLOC_ACCESSIBLE, \
>> + MAX_NUMNODES)
>> +#define memblock_virt_alloc_node(x, nid) \
>> + memblock_virt_alloc_try_nid(x, SMP_CACHE_BYTES, BOOTMEM_LOW_LIMIT, \
>> + BOOTMEM_ALLOC_ACCESSIBLE, nid)
>> +#define memblock_virt_alloc_node_nopanic(x, nid) \

Regards,
- grygorii



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