mm/hugetlb_vmemmap.h

   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 */