Re: [PATCH v3] mm/hugetlb: split hugetlb_cma in nodes with memory

[Anshuman Khandual]

On 07/16/2020 11:55 PM, Mike Kravetz wrote:
>>From 17c8f37afbf42fe7412e6eebb3619c6e0b7e1c3c Mon Sep 17 00:00:00 2001
> From: Mike Kravetz <mike.kravetz@xxxxxxxxxx>
> Date: Tue, 14 Jul 2020 15:54:46 -0700
> Subject: [PATCH] hugetlb: move cma reservation to code setting up gigantic
>  hstate
> 
> Instead of calling hugetlb_cma_reserve() directly from arch specific
> code, call from hugetlb_add_hstate when adding a gigantic hstate.
> hugetlb_add_hstate is either called from arch specific huge page setup,
> or as the result of hugetlb command line processing.  In either case,
> this is late enough in the init process that all numa memory information
> should be initialized.  And, it is early enough to still use early
> memory allocator.

This assumes that hugetlb_add_hstate() is called from the arch code at
the right point in time for the generic HugeTLB to do the required CMA
reservation which is not ideal. I guess it must have been a reason why
CMA reservation should always called by the platform code which knows
the boot sequence timing better.