1 // SPDX-License-Identifier: GPL-2.0 2 /* 3 * HugeTLB Vmemmap Optimization (HVO) 4 * 5 * Copyright (c) 2020, ByteDance. All rights reserved. 6 * 7 * Author: Muchun Song <songmuchun@bytedance.com> 8 */ 9 #ifndef _LINUX_HUGETLB_VMEMMAP_H 10 #define _LINUX_HUGETLB_VMEMMAP_H 11 #include <linux/hugetlb.h> 12 13 /* 14 * Reserve one vmemmap page, all vmemmap addresses are mapped to it. See 15 * Documentation/mm/vmemmap_dedup.rst. 16 */ 17 #define HUGETLB_VMEMMAP_RESERVE_SIZE PAGE_SIZE 18 #define HUGETLB_VMEMMAP_RESERVE_PAGES (HUGETLB_VMEMMAP_RESERVE_SIZE / sizeof(struct page)) 19 20 #ifdef CONFIG_HUGETLB_PAGE_OPTIMIZE_VMEMMAP 21 int hugetlb_vmemmap_restore_folio(const struct hstate *h, struct folio *folio); 22 long hugetlb_vmemmap_restore_folios(const struct hstate *h, 23 struct list_head *folio_list, 24 struct list_head *non_hvo_folios); 25 void hugetlb_vmemmap_optimize_folio(const struct hstate *h, struct folio *folio); 26 void hugetlb_vmemmap_optimize_folios(struct hstate *h, struct list_head *folio_list); 27 28 static inline unsigned int hugetlb_vmemmap_size(const struct hstate *h) 29 { 30 return pages_per_huge_page(h) * sizeof(struct page); 31 } 32 33 /* 34 * Return how many vmemmap size associated with a HugeTLB page that can be 35 * optimized and can be freed to the buddy allocator. 36 */ 37 static inline unsigned int hugetlb_vmemmap_optimizable_size(const struct hstate *h) 38 { 39 int size = hugetlb_vmemmap_size(h) - HUGETLB_VMEMMAP_RESERVE_SIZE; 40 41 if (!is_power_of_2(sizeof(struct page))) 42 return 0; 43 return size > 0 ? size : 0; 44 } 45 #else 46 static inline int hugetlb_vmemmap_restore_folio(const struct hstate *h, struct folio *folio) 47 { 48 return 0; 49 } 50 51 static long hugetlb_vmemmap_restore_folios(const struct hstate *h, 52 struct list_head *folio_list, 53 struct list_head *non_hvo_folios) 54 { 55 list_splice_init(folio_list, non_hvo_folios); 56 return 0; 57 } 58 59 static inline void hugetlb_vmemmap_optimize_folio(const struct hstate *h, struct folio *folio) 60 { 61 } 62 63 static inline void hugetlb_vmemmap_optimize_folios(struct hstate *h, struct list_head *folio_list) 64 { 65 } 66 67 static inline unsigned int hugetlb_vmemmap_optimizable_size(const struct hstate *h) 68 { 69 return 0; 70 } 71 #endif /* CONFIG_HUGETLB_PAGE_OPTIMIZE_VMEMMAP */ 72 73 static inline bool hugetlb_vmemmap_optimizable(const struct hstate *h) 74 { 75 return hugetlb_vmemmap_optimizable_size(h) != 0; 76 } 77 #endif /* _LINUX_HUGETLB_VMEMMAP_H */ 78