Re: [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@xxxxxxxxxxxxxx>
> > Reviewed-by: Gavin Shan <gshan@xxxxxxxxxx>
> > Reviewed-by: Anshuman Khandual <anshuman.khandual@xxxxxxx>
> > Cc: Catalin Marinas <catalin.marinas@xxxxxxx>
> > Cc: Will Deacon <will@xxxxxxxxxx>
> > Cc: Anshuman Khandual <anshuman.khandual@xxxxxxx>
> > Cc: Mark Rutland <mark.rutland@xxxxxxx>
> > Cc: Logan Gunthorpe <logang@xxxxxxxxxxxx>
> > Cc: David Hildenbrand <david@xxxxxxxxxx>
> > Cc: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
> > Cc: Steven Price <steven.price@xxxxxxx>
> > ---
> >  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

--
Qualcomm Innovation Center, Inc. is a member of Code Aurora Forum, a 
Linux Foundation Collaborative Project