mm, arch: consolidate hugetlb CMA reservation

Every architecture that supports hugetlb_cma command line parameter
reserves CMA areas for hugetlb during setup_arch().

This obfuscates the ordering of hugetlb CMA initialization with respect to
the rest initialization of the core MM.

Introduce arch_hugetlb_cma_order() callback to allow architectures report
the desired order-per-bit of CMA areas and provide a week implementation
of arch_hugetlb_cma_order() for architectures that don't support hugetlb
with CMA.

Use this callback in hugetlb_cma_reserve() instead if passing the order as
parameter and call hugetlb_cma_reserve() from mm_core_init_early() rather
than have it spread over architecture specific code.

Link: https://lkml.kernel.org/r/20260111082105.290734-28-rppt@kernel.org
Signed-off-by: Mike Rapoport (Microsoft) <rppt@kernel.org>
Cc: Alexander Gordeev <agordeev@linux.ibm.com>
Cc: Alex Shi <alexs@kernel.org>
Cc: Andreas Larsson <andreas@gaisler.com>
Cc: "Borislav Petkov (AMD)" <bp@alien8.de>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: David Hildenbrand <david@kernel.org>
Cc: David S. Miller <davem@davemloft.net>
Cc: Dinh Nguyen <dinguyen@kernel.org>
Cc: Geert Uytterhoeven <geert@linux-m68k.org>
Cc: Guo Ren <guoren@kernel.org>
Cc: Heiko Carstens <hca@linux.ibm.com>
Cc: Helge Deller <deller@gmx.de>
Cc: Huacai Chen <chenhuacai@kernel.org>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Johannes Berg <johannes@sipsolutions.net>
Cc: John Paul Adrian Glaubitz <glaubitz@physik.fu-berlin.de>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Klara Modin <klarasmodin@gmail.com>
Cc: Liam Howlett <liam.howlett@oracle.com>
Cc: Lorenzo Stoakes <lorenzo.stoakes@oracle.com>
Cc: Magnus Lindholm <linmag7@gmail.com>
Cc: Matt Turner <mattst88@gmail.com>
Cc: Max Filippov <jcmvbkbc@gmail.com>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Michal Simek <monstr@monstr.eu>
Cc: Muchun Song <muchun.song@linux.dev>
Cc: Oscar Salvador <osalvador@suse.de>
Cc: Palmer Dabbelt <palmer@dabbelt.com>
Cc: Pratyush Yadav <pratyush@kernel.org>
Cc: Richard Weinberger <richard@nod.at>
Cc: "Ritesh Harjani (IBM)" <ritesh.list@gmail.com>
Cc: Russell King <linux@armlinux.org.uk>
Cc: Stafford Horne <shorne@gmail.com>
Cc: Suren Baghdasaryan <surenb@google.com>
Cc: Thomas Bogendoerfer <tsbogend@alpha.franken.de>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Vasily Gorbik <gor@linux.ibm.com>
Cc: Vineet Gupta <vgupta@kernel.org>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Will Deacon <will@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

3 files changed, 4 insertions, 13 deletions

diff --git a/arch/powerpc/include/asm/hugetlb.h b/arch/powerpc/include/asm/hugetlb.h
index 86326587e58d..6d32a4299445 100644
--- a/arch/powerpc/include/asm/hugetlb.h
+++ b/arch/powerpc/include/asm/hugetlb.h
@@ -68,7 +68,6 @@ int huge_ptep_set_access_flags(struct vm_area_struct *vma,
 			       unsigned long addr, pte_t *ptep,
 			       pte_t pte, int dirty);
 
-void gigantic_hugetlb_cma_reserve(void) __init;
 #include <asm-generic/hugetlb.h>
 
 #else /* ! CONFIG_HUGETLB_PAGE */
@@ -77,10 +76,6 @@ static inline void flush_hugetlb_page(struct vm_area_struct *vma,
 {
 }
 
-static inline void __init gigantic_hugetlb_cma_reserve(void)
-{
-}
-
 static inline void __init hugetlbpage_init_defaultsize(void)
 {
 }
diff --git a/arch/powerpc/kernel/setup-common.c b/arch/powerpc/kernel/setup-common.c
index c8c42b419742..cb5b73adc250 100644
--- a/arch/powerpc/kernel/setup-common.c
+++ b/arch/powerpc/kernel/setup-common.c
@@ -1003,7 +1003,6 @@ void __init setup_arch(char **cmdline_p)
 	fadump_cma_init();
 	kdump_cma_reserve();
 	kvm_cma_reserve();
-	gigantic_hugetlb_cma_reserve();
 
 	early_memtest(min_low_pfn << PAGE_SHIFT, max_low_pfn << PAGE_SHIFT);
 
diff --git a/arch/powerpc/mm/hugetlbpage.c b/arch/powerpc/mm/hugetlbpage.c
index d3c1b749dcfc..558fafb82b8a 100644
--- a/arch/powerpc/mm/hugetlbpage.c
+++ b/arch/powerpc/mm/hugetlbpage.c
@@ -200,18 +200,15 @@ static int __init hugetlbpage_init(void)
 
 arch_initcall(hugetlbpage_init);
 
-void __init gigantic_hugetlb_cma_reserve(void)
+unsigned int __init arch_hugetlb_cma_order(void)
 {
-	unsigned long order = 0;
-
 	if (radix_enabled())
-		order = PUD_SHIFT - PAGE_SHIFT;
+		return PUD_SHIFT - PAGE_SHIFT;
 	else if (!firmware_has_feature(FW_FEATURE_LPAR) && mmu_psize_defs[MMU_PAGE_16G].shift)
 		/*
 		 * For pseries we do use ibm,expected#pages for reserving 16G pages.
 		 */
-		order = mmu_psize_to_shift(MMU_PAGE_16G) - PAGE_SHIFT;
+		return mmu_psize_to_shift(MMU_PAGE_16G) - PAGE_SHIFT;
 
-	if (order)
-		hugetlb_cma_reserve(order);
+	return 0;
 }