[PATCH 08/16] mm/vmemmap: Improve vmemmap_can_optimize and allow architectures to override
From: Aneesh Kumar K.V <hidden>
Date: 2023-06-06 05:04:27
Subsystem:
memblock and memory management initialization, memory management, memory management - core, the rest · Maintainers:
Mike Rapoport, Andrew Morton, David Hildenbrand, Linus Torvalds
dax vmemmap optimization requires a minimum of 2 PAGE_SIZE area within vmemmap such that tail page mapping can point to the second PAGE_SIZE area. Enforce that in vmemmap_can_optimize() function. Architectures like powerpc also want to enable vmemmap optimization conditionally (only with radix MMU translation). Hence allow architecture override. Signed-off-by: Aneesh Kumar K.V <redacted> --- include/linux/mm.h | 30 ++++++++++++++++++++++++++---- mm/mm_init.c | 2 +- 2 files changed, 27 insertions(+), 5 deletions(-)
diff --git a/include/linux/mm.h b/include/linux/mm.h
index 27ce77080c79..9a45e61cd83f 100644
--- a/include/linux/mm.h
+++ b/include/linux/mm.h@@ -31,6 +31,8 @@ #include <linux/memremap.h> #include <linux/slab.h> +#include <asm/page.h> + struct mempolicy; struct anon_vma; struct anon_vma_chain;
@@ -3550,13 +3552,33 @@ void vmemmap_free(unsigned long start, unsigned long end, struct vmem_altmap *altmap); #endif +#define VMEMMAP_RESERVE_NR 2 #ifdef CONFIG_ARCH_WANT_OPTIMIZE_VMEMMAP -static inline bool vmemmap_can_optimize(struct vmem_altmap *altmap, - struct dev_pagemap *pgmap) +static inline bool __vmemmap_can_optimize(struct vmem_altmap *altmap, + struct dev_pagemap *pgmap) { - return is_power_of_2(sizeof(struct page)) && - pgmap && (pgmap_vmemmap_nr(pgmap) > 1) && !altmap; + if (pgmap) { + unsigned long nr_pages; + unsigned long nr_vmemmap_pages; + + nr_pages = pgmap_vmemmap_nr(pgmap); + nr_vmemmap_pages = ((nr_pages * sizeof(struct page)) >> PAGE_SHIFT); + /* + * For vmemmap optimization with DAX we need minimum 2 vmemmap + * pages. See layout diagram in Documentation/mm/vmemmap_dedup.rst + */ + return is_power_of_2(sizeof(struct page)) && + (nr_vmemmap_pages > VMEMMAP_RESERVE_NR) && !altmap; + } + return false; } +/* + * If we don't have an architecture override, use the generic rule + */ +#ifndef vmemmap_can_optimize +#define vmemmap_can_optimize __vmemmap_can_optimize +#endif + #else static inline bool vmemmap_can_optimize(struct vmem_altmap *altmap, struct dev_pagemap *pgmap)
diff --git a/mm/mm_init.c b/mm/mm_init.c
index 7f7f9c677854..d1676afc94f1 100644
--- a/mm/mm_init.c
+++ b/mm/mm_init.c@@ -1020,7 +1020,7 @@ static inline unsigned long compound_nr_pages(struct vmem_altmap *altmap, if (!vmemmap_can_optimize(altmap, pgmap)) return pgmap_vmemmap_nr(pgmap); - return 2 * (PAGE_SIZE / sizeof(struct page)); + return VMEMMAP_RESERVE_NR * (PAGE_SIZE / sizeof(struct page)); } static void __ref memmap_init_compound(struct page *head,
--
2.40.1