[PATCH v3] arm64/mm: add fallback option to allocate virtually contiguous memory

[Sudarshan Rajagopalan]

On 2020-10-15 01:36, Will Deacon wrote:
> On Wed, Oct 14, 2020 at 05:51:23PM -0700, Sudarshan Rajagopalan wrote:
>> When section mappings are enabled, we allocate vmemmap pages from
>> physically continuous memory of size PMD_SIZE using
>> vmemmap_alloc_block_buf(). Section mappings are good to reduce TLB
>> pressure. But when system is highly fragmented and memory blocks are
>> being hot-added at runtime, its possible that such physically 
>> continuous
>> memory allocations can fail. Rather than failing the memory hot-add
>> procedure, add a fallback option to allocate vmemmap pages from
>> discontinuous pages using vmemmap_populate_basepages().
>> 
>> Signed-off-by: Sudarshan Rajagopalan <sudaraja at codeaurora.org>
>> Reviewed-by: Gavin Shan <gshan at redhat.com>
>> Reviewed-by: Anshuman Khandual <anshuman.khandual at arm.com>
>> Cc: Catalin Marinas <catalin.marinas at arm.com>
>> Cc: Will Deacon <will at kernel.org>
>> Cc: Anshuman Khandual <anshuman.khandual at arm.com>
>> Cc: Mark Rutland <mark.rutland at arm.com>
>> Cc: Logan Gunthorpe <logang at deltatee.com>
>> Cc: David Hildenbrand <david at redhat.com>
>> Cc: Andrew Morton <akpm at linux-foundation.org>
>> Cc: Steven Price <steven.price at arm.com>
>> ---
>>  arch/arm64/mm/mmu.c | 7 +++++--
>>  1 file changed, 5 insertions(+), 2 deletions(-)
> 
> Please can you fix the subject? I have three copies of "PATCH v3" from
> different days in my inbox. I know it sounds trivial, but getting these
> little things right really helps with review, especially when it's 
> sitting
> amongst a sea of other patches.

Yes sure, sorry about that - will change it to "PATCH v4" to make it 
stand out from other patches.

> 
> Thanks,
> 
> Will


Sudarshan

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