// SPDX-License-Identifier: GPL-2.0 /* * HugeTLB Vmemmap Optimization (HVO) * * Copyright (c) 2020, ByteDance. All rights reserved. * * Author: Muchun Song <songmuchun@bytedance.com> */ #ifndef _LINUX_HUGETLB_VMEMMAP_H #define _LINUX_HUGETLB_VMEMMAP_H #include <linux/hugetlb.h> /* * Reserve one vmemmap page, all vmemmap addresses are mapped to it. See * Documentation/mm/vmemmap_dedup.rst. */ #define HUGETLB_VMEMMAP_RESERVE_SIZE PAGE_SIZE #define HUGETLB_VMEMMAP_RESERVE_PAGES (HUGETLB_VMEMMAP_RESERVE_SIZE / sizeof(struct page)) #ifdef CONFIG_HUGETLB_PAGE_OPTIMIZE_VMEMMAP int hugetlb_vmemmap_restore_folio(const struct hstate *h, struct folio *folio); long hugetlb_vmemmap_restore_folios(const struct hstate *h, struct list_head *folio_list, struct list_head *non_hvo_folios); void hugetlb_vmemmap_optimize_folio(const struct hstate *h, struct folio *folio); void hugetlb_vmemmap_optimize_folios(struct hstate *h, struct list_head *folio_list); static inline unsigned int hugetlb_vmemmap_size(const struct hstate *h) { return pages_per_huge_page(h) * sizeof(struct page); } /* * Return how many vmemmap size associated with a HugeTLB page that can be * optimized and can be freed to the buddy allocator. */ static inline unsigned int hugetlb_vmemmap_optimizable_size(const struct hstate *h) { int size = hugetlb_vmemmap_size(h) - HUGETLB_VMEMMAP_RESERVE_SIZE; if (!is_power_of_2(sizeof(struct page))) return 0; return size > 0 ? size : 0; } #else static inline int hugetlb_vmemmap_restore_folio(const struct hstate *h, struct folio *folio) { return 0; } static long hugetlb_vmemmap_restore_folios(const struct hstate *h, struct list_head *folio_list, struct list_head *non_hvo_folios) { list_splice_init(folio_list, non_hvo_folios); return 0; } static inline void hugetlb_vmemmap_optimize_folio(const struct hstate *h, struct folio *folio) { } static inline void hugetlb_vmemmap_optimize_folios(struct hstate *h, struct list_head *folio_list) { } static inline unsigned int hugetlb_vmemmap_optimizable_size(const struct hstate *h) { return 0; } #endif /* CONFIG_HUGETLB_PAGE_OPTIMIZE_VMEMMAP */ static inline bool hugetlb_vmemmap_optimizable(const struct hstate *h) { return hugetlb_vmemmap_optimizable_size(h) != 0; } #endif /* _LINUX_HUGETLB_VMEMMAP_H */