Re: [PATCH 1/4] hugetlbfs: add arch_hugetlb_valid_size

The architecture independent routine hugetlb_default_setup sets up
the default huge pages size.  It has no way to verify if the passed
value is valid, so it accepts it and attempts to validate at a later
time.  This requires undocumented cooperation between the arch specific
and arch independent code.

For architectures that support more than one huge page size, provide
a routine arch_hugetlb_valid_size to validate a huge page size.
hugetlb_default_setup can use this to validate passed values.

arch_hugetlb_valid_size will also be used in a subsequent patch to
move processing of the "hugepagesz=" in arch specific code to a common
routine in arch independent code.

Signed-off-by: Mike Kravetz <redacted>
---
 arch/arm64/include/asm/hugetlb.h   |  2 ++
 arch/arm64/mm/hugetlbpage.c        | 19 ++++++++++++++-----
 arch/powerpc/include/asm/hugetlb.h |  3 +++
 arch/powerpc/mm/hugetlbpage.c      | 20 +++++++++++++-------
 arch/riscv/include/asm/hugetlb.h   |  3 +++
 arch/riscv/mm/hugetlbpage.c        | 28 ++++++++++++++++++----------
 arch/s390/include/asm/hugetlb.h    |  3 +++
 arch/s390/mm/hugetlbpage.c         | 18 +++++++++++++-----
 arch/sparc/include/asm/hugetlb.h   |  3 +++
 arch/sparc/mm/init_64.c            | 23 ++++++++++++++++-------
 arch/x86/include/asm/hugetlb.h     |  3 +++
 arch/x86/mm/hugetlbpage.c          | 21 +++++++++++++++------
 include/linux/hugetlb.h            |  7 +++++++
 mm/hugetlb.c                       | 16 +++++++++++++---
 14 files changed, 126 insertions(+), 43 deletions(-)

diff --git a/arch/arm64/include/asm/hugetlb.h b/arch/arm64/include/asm/hugetlb.h
index 2eb6c234d594..3248f35213ee 100644
--- a/arch/arm64/include/asm/hugetlb.h
+++ b/arch/arm64/include/asm/hugetlb.h

@@ -59,6 +59,8 @@ extern void huge_pte_clear(struct mm_struct *mm, unsigned long addr,
 extern void set_huge_swap_pte_at(struct mm_struct *mm, unsigned long addr,
 				 pte_t *ptep, pte_t pte, unsigned long sz);
 #define set_huge_swap_pte_at set_huge_swap_pte_at
+extern bool __init arch_hugetlb_valid_size(unsigned long long size);
+#define arch_hugetlb_valid_size arch_hugetlb_valid_size
 
 #include <asm-generic/hugetlb.h>
 

diff --git a/arch/arm64/mm/hugetlbpage.c b/arch/arm64/mm/hugetlbpage.c
index bbeb6a5a6ba6..da30127086d0 100644
--- a/arch/arm64/mm/hugetlbpage.c
+++ b/arch/arm64/mm/hugetlbpage.c

@@ -462,23 +462,32 @@ static int __init hugetlbpage_init(void)
 }
 arch_initcall(hugetlbpage_init);
 
-static __init int setup_hugepagesz(char *opt)
+bool __init arch_hugetlb_valid_size(unsigned long long size)
 {
-	unsigned long ps = memparse(opt, &opt);
-
-	switch (ps) {
+	switch (size) {
 #ifdef CONFIG_ARM64_4K_PAGES
 	case PUD_SIZE:
 #endif
 	case CONT_PMD_SIZE:
 	case PMD_SIZE:
 	case CONT_PTE_SIZE:
+		return true;
+	}
+
+	return false;
+}
+
+static __init int setup_hugepagesz(char *opt)
+{
+	unsigned long long ps = memparse(opt, &opt);
+
+	if arch_hugetlb_valid_size(ps)) {