I agree we should only be concerned with N_MEMORY nodes for the CMA
reservations.  However, this patch got me thinking:
- Do we really have to initiate the CMA reservations from arch specific code?
- Can we move the call to reserve CMA a little later into hugetlb arch
  independent code?

I know the cma_declare_contiguous_nid() routine says it should be called
from arch specific code.  However, unless I am missing something that seems
mostly about timing.

What about a change like this on top of this patch?

From 72b5b9a623f8711ad7f79f1a8f910906245f5d07 Mon Sep 17 00:00:00 2001
From: Mike Kravetz <redacted>
Date: Tue, 14 Jul 2020 15:54:46 -0700
Subject: [PATCH] hugetlb: move cma allocation call to arch independent code

Instead of calling hugetlb_cma_reserve() from arch specific code,
call from arch independent code when a gigantic page hstate is
created.  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.

Signed-off-by: Mike Kravetz <redacted>
---
 arch/arm64/mm/init.c    | 10 ----------
 arch/x86/kernel/setup.c |  9 ---------
 mm/hugetlb.c            |  8 +++++++-
 3 files changed, 7 insertions(+), 20 deletions(-)

diff --git a/arch/arm64/mm/init.c b/arch/arm64/mm/init.c
index 79806732f4b4..ff0ff584dde9 100644
--- a/arch/arm64/mm/init.c
+++ b/arch/arm64/mm/init.c

@@ -427,16 +427,6 @@ void __init bootmem_init(void)
 	sparse_init();
 	zone_sizes_init(min, max);
 
-	/*
-	 * must be done after zone_sizes_init() which calls free_area_init()
-	 * that calls node_set_state() to initialize node_states[N_MEMORY]
-	 * because hugetlb_cma_reserve() will scan over nodes with N_MEMORY
-	 * state
-	 */
-#ifdef CONFIG_ARM64_4K_PAGES
-	hugetlb_cma_reserve(PUD_SHIFT - PAGE_SHIFT);
-#endif
-
 	memblock_dump_all();
 }
 

diff --git a/arch/x86/kernel/setup.c b/arch/x86/kernel/setup.c
index a1a9712090ae..111c8467fafa 100644
--- a/arch/x86/kernel/setup.c
+++ b/arch/x86/kernel/setup.c

@@ -1177,15 +1177,6 @@ void __init setup_arch(char **cmdline_p)
 
 	x86_init.paging.pagetable_init();
 
-	/*
-	 * must be done after zone_sizes_init() which calls free_area_init()
-	 * that calls node_set_state() to initialize node_states[N_MEMORY]
-	 * because hugetlb_cma_reserve() will scan over nodes with N_MEMORY
-	 * state
-	 */
-	if (boot_cpu_has(X86_FEATURE_GBPAGES))
-		hugetlb_cma_reserve(PUD_SHIFT - PAGE_SHIFT);
-
 	kasan_init();
 
 	/*

diff --git a/mm/hugetlb.c b/mm/hugetlb.c
index f24acb3af741..a0007d1d12d2 100644
--- a/mm/hugetlb.c
+++ b/mm/hugetlb.c

@@ -3273,6 +3273,9 @@ void __init hugetlb_add_hstate(unsigned int order)
 	snprintf(h->name, HSTATE_NAME_LEN, "hugepages-%lukB",
 					huge_page_size(h)/1024);

+
 	parsed_hstate = h;
 }
 

@@ -5647,7 +5650,10 @@ void __init hugetlb_cma_reserve(int order)
 	unsigned long size, reserved, per_node;
 	int nid;
 
-	cma_reserve_called = true;
+	if (cma_reserve_called)
+		return;
+	else
+		cma_reserve_called = true;