[PATCH v17 7/9] mm: hugetlb: introduce nr_free_vmemmap_pages in the struct hstate
From: Muchun Song <hidden>
Date: 2021-02-25 13:27:27
Also in:
linux-fsdevel, linux-mm, lkml
Subsystem:
hugetlb subsystem, memory management, the rest · Maintainers:
Muchun Song, Oscar Salvador, Andrew Morton, Linus Torvalds
All the infrastructure is ready, so we introduce nr_free_vmemmap_pages field in the hstate to indicate how many vmemmap pages associated with a HugeTLB page that can be freed to buddy allocator. And initialize it in the hugetlb_vmemmap_init(). This patch is actual enablement of the feature. Signed-off-by: Muchun Song <redacted> Acked-by: Mike Kravetz <redacted> Reviewed-by: Oscar Salvador <osalvador@suse.de> Reviewed-by: Miaohe Lin <linmiaohe@huawei.com> --- include/linux/hugetlb.h | 3 +++ mm/hugetlb.c | 1 + mm/hugetlb_vmemmap.c | 25 +++++++++++++++++++++++++ mm/hugetlb_vmemmap.h | 10 ++++++---- 4 files changed, 35 insertions(+), 4 deletions(-)
diff --git a/include/linux/hugetlb.h b/include/linux/hugetlb.h
index 78934e9aeab6..a4d80f7263fc 100644
--- a/include/linux/hugetlb.h
+++ b/include/linux/hugetlb.h@@ -560,6 +560,9 @@ struct hstate { unsigned int nr_huge_pages_node[MAX_NUMNODES]; unsigned int free_huge_pages_node[MAX_NUMNODES]; unsigned int surplus_huge_pages_node[MAX_NUMNODES]; +#ifdef CONFIG_HUGETLB_PAGE_FREE_VMEMMAP + unsigned int nr_free_vmemmap_pages; +#endif #ifdef CONFIG_CGROUP_HUGETLB /* cgroup control files */ struct cftype cgroup_files_dfl[7];
diff --git a/mm/hugetlb.c b/mm/hugetlb.c
index bccb6907833f..4d192ba183f9 100644
--- a/mm/hugetlb.c
+++ b/mm/hugetlb.c@@ -3312,6 +3312,7 @@ void __init hugetlb_add_hstate(unsigned int order) h->next_nid_to_free = first_memory_node; snprintf(h->name, HSTATE_NAME_LEN, "hugepages-%lukB", huge_page_size(h)/1024); + hugetlb_vmemmap_init(h); parsed_hstate = h; }
diff --git a/mm/hugetlb_vmemmap.c b/mm/hugetlb_vmemmap.c
index 7807ed6678e0..b65f0d5189bd 100644
--- a/mm/hugetlb_vmemmap.c
+++ b/mm/hugetlb_vmemmap.c@@ -251,3 +251,28 @@ void free_huge_page_vmemmap(struct hstate *h, struct page *head) */ vmemmap_remap_free(vmemmap_addr, vmemmap_end, vmemmap_reuse); } + +void __init hugetlb_vmemmap_init(struct hstate *h) +{ + unsigned int nr_pages = pages_per_huge_page(h); + unsigned int vmemmap_pages; + + if (!hugetlb_free_vmemmap_enabled) + return; + + vmemmap_pages = (nr_pages * sizeof(struct page)) >> PAGE_SHIFT; + /* + * The head page and the first tail page are not to be freed to buddy + * allocator, the other pages will map to the first tail page, so they + * can be freed. + * + * Could RESERVE_VMEMMAP_NR be greater than @vmemmap_pages? It is true + * on some architectures (e.g. aarch64). See Documentation/arm64/ + * hugetlbpage.rst for more details. + */ + if (likely(vmemmap_pages > RESERVE_VMEMMAP_NR)) + h->nr_free_vmemmap_pages = vmemmap_pages - RESERVE_VMEMMAP_NR; + + pr_info("can free %d vmemmap pages for %s\n", h->nr_free_vmemmap_pages, + h->name); +}
diff --git a/mm/hugetlb_vmemmap.h b/mm/hugetlb_vmemmap.h
index a37771b0b82a..cb2bef8f9e73 100644
--- a/mm/hugetlb_vmemmap.h
+++ b/mm/hugetlb_vmemmap.h@@ -13,17 +13,15 @@ #ifdef CONFIG_HUGETLB_PAGE_FREE_VMEMMAP int alloc_huge_page_vmemmap(struct hstate *h, struct page *head); void free_huge_page_vmemmap(struct hstate *h, struct page *head); +void hugetlb_vmemmap_init(struct hstate *h); /* * How many vmemmap pages associated with a HugeTLB page that can be freed * to the buddy allocator. - * - * Todo: Returns zero for now, which means the feature is disabled. We will - * enable it once all the infrastructure is there. */ static inline unsigned int free_vmemmap_pages_per_hpage(struct hstate *h) { - return 0; + return h->nr_free_vmemmap_pages; } #else static inline int alloc_huge_page_vmemmap(struct hstate *h, struct page *head)
@@ -35,6 +33,10 @@ static inline void free_huge_page_vmemmap(struct hstate *h, struct page *head) { } +static inline void hugetlb_vmemmap_init(struct hstate *h) +{ +} + static inline unsigned int free_vmemmap_pages_per_hpage(struct hstate *h) { return 0;
--
2.11.0