Currently 'hugetlb_cma=' command line argument does not create CMA area on ARM64_16K_PAGES and ARM64_64K_PAGES based platforms. Instead, it just ends up with the following warning message. Reason being, hugetlb_cma_reserve() never gets called for these huge page sizes.
[ 64.255669] hugetlb_cma: the option isn't supported by current arch This enables CMA areas reservation on ARM64_16K_PAGES and ARM64_64K_PAGES configs by defining an unified arm64_hugetlb_cma_reseve() that is wrapped in CONFIG_CMA. Call site for arm64_hugetlb_cma_reserve() is also protected as <asm/hugetlb.h> is conditionally included and hence cannot contain stub for the inverse config i.e !(CONFIG_HUGETLB_PAGE && CONFIG_CMA). Cc: Catalin Marinas <[email protected]> Cc: Will Deacon <[email protected]> Cc: Mark Rutland <[email protected]> Cc: Mike Kravetz <[email protected]> Cc: Barry Song <[email protected]> Cc: Andrew Morton <[email protected]> Cc: [email protected] Cc: [email protected] Signed-off-by: Anshuman Khandual <[email protected]> --- Applies on 5.8-rc3. Changes in V3: - Dropped the stub, protected call site, moved the declaration to a header Changes in V2: (https://patchwork.kernel.org/patch/11630503/) - Moved arm64_hugetlb_cma_reserve() stub and declaration near call site Changes in V1: (https://patchwork.kernel.org/patch/11619839/) arch/arm64/include/asm/hugetlb.h | 2 ++ arch/arm64/mm/hugetlbpage.c | 38 ++++++++++++++++++++++++++++++++ arch/arm64/mm/init.c | 4 ++-- 3 files changed, 42 insertions(+), 2 deletions(-) diff --git a/arch/arm64/include/asm/hugetlb.h b/arch/arm64/include/asm/hugetlb.h index 94ba0c5bced2..5abf91e3494c 100644 --- a/arch/arm64/include/asm/hugetlb.h +++ b/arch/arm64/include/asm/hugetlb.h @@ -49,6 +49,8 @@ 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 +void __init arm64_hugetlb_cma_reserve(void); + #include <asm-generic/hugetlb.h> #endif /* __ASM_HUGETLB_H */ diff --git a/arch/arm64/mm/hugetlbpage.c b/arch/arm64/mm/hugetlbpage.c index 0a52ce46f020..ea7fb48b8617 100644 --- a/arch/arm64/mm/hugetlbpage.c +++ b/arch/arm64/mm/hugetlbpage.c @@ -19,6 +19,44 @@ #include <asm/tlbflush.h> #include <asm/pgalloc.h> +/* + * HugeTLB Support Matrix + * + * --------------------------------------------------- + * | Page Size | CONT PTE | PMD | CONT PMD | PUD | + * --------------------------------------------------- + * | 4K | 64K | 2M | 32M | 1G | + * | 16K | 2M | 32M | 1G | | + * | 64K | 2M | 512M | 16G | | + * --------------------------------------------------- + */ + +/* + * Reserve CMA areas for the largest supported gigantic + * huge page when requested. Any other smaller gigantic + * huge pages could still be served from those areas. + */ +#ifdef CONFIG_CMA +void __init arm64_hugetlb_cma_reserve(void) +{ + int order; + +#ifdef CONFIG_ARM64_4K_PAGES + order = PUD_SHIFT - PAGE_SHIFT; +#else + order = CONT_PMD_SHIFT + PMD_SHIFT - PAGE_SHIFT; +#endif + /* + * HugeTLB CMA reservation is required for gigantic + * huge pages which could not be allocated via the + * page allocator. Just warn if there is any change + * breaking this assumption. + */ + WARN_ON(order <= MAX_ORDER); + hugetlb_cma_reserve(order); +} +#endif /* CONFIG_CMA */ + #ifdef CONFIG_ARCH_ENABLE_HUGEPAGE_MIGRATION bool arch_hugetlb_migration_supported(struct hstate *h) { diff --git a/arch/arm64/mm/init.c b/arch/arm64/mm/init.c index 1e93cfc7c47a..5f5665b9b026 100644 --- a/arch/arm64/mm/init.c +++ b/arch/arm64/mm/init.c @@ -425,8 +425,8 @@ void __init bootmem_init(void) * initialize node_online_map that gets used in hugetlb_cma_reserve() * while allocating required CMA size across online nodes. */ -#ifdef CONFIG_ARM64_4K_PAGES - hugetlb_cma_reserve(PUD_SHIFT - PAGE_SHIFT); +#if defined(CONFIG_HUGETLB_PAGE) && defined(CONFIG_CMA) + arm64_hugetlb_cma_reserve(); #endif /* -- 2.20.1
