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// 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 */
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