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mm: hugetlb: introduce nr_free_vmemmap_pages in the struct hstate

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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.

There are only (RESERVE_VMEMMAP_SIZE / sizeof(struct page)) struct page
structs that can be used when CONFIG_HUGETLB_PAGE_FREE_VMEMMAP, so add a
BUILD_BUG_ON to catch invalid usage of the tail struct page.

Link: https://lkml.kernel.org/r/20210510030027.56044-10-songmuchun@bytedance.com
Signed-off-by: Muchun Song <songmuchun@bytedance.com>
Acked-by: Mike Kravetz <mike.kravetz@oracle.com>
Reviewed-by: Oscar Salvador <osalvador@suse.de>
Reviewed-by: Miaohe Lin <linmiaohe@huawei.com>
Tested-by: Chen Huang <chenhuang5@huawei.com>
Tested-by: Bodeddula Balasubramaniam <bodeddub@amazon.com>
Cc: Alexander Viro <viro@zeniv.linux.org.uk>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Anshuman Khandual <anshuman.khandual@arm.com>
Cc: Balbir Singh <bsingharora@gmail.com>
Cc: Barry Song <song.bao.hua@hisilicon.com>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: David Hildenbrand <david@redhat.com>
Cc: David Rientjes <rientjes@google.com>
Cc: HORIGUCHI NAOYA <naoya.horiguchi@nec.com>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Joao Martins <joao.m.martins@oracle.com>
Cc: Joerg Roedel <jroedel@suse.de>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Mina Almasry <almasrymina@google.com>
Cc: Oliver Neukum <oneukum@suse.com>
Cc: Paul E. McKenney <paulmck@kernel.org>
Cc: Pawan Gupta <pawan.kumar.gupta@linux.intel.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Randy Dunlap <rdunlap@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Xiongchun Duan <duanxiongchun@bytedance.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Muchun Song 2021-06-30 18:47:33 -07:00 committed by Linus Torvalds
parent 4bab4964a5
commit 774905878f
4 changed files with 43 additions and 4 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

3
include/linux/hugetlb.h
View File

@ -608,6 +608,9 @@ 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];

1
mm/hugetlb.c
View File

@ -3585,6 +3585,7 @@ 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;
}

33
mm/hugetlb_vmemmap.c
View File

@ -262,3 +262,36 @@ void free_huge_page_vmemmap(struct hstate *h, struct page *head)
SetHPageVmemmapOptimized(head);
}
void __init hugetlb_vmemmap_init(struct hstate *h)
{
unsigned int nr_pages = pages_per_huge_page(h);
unsigned int vmemmap_pages;
/*
* There are only (RESERVE_VMEMMAP_SIZE / sizeof(struct page)) struct
* page structs that can be used when CONFIG_HUGETLB_PAGE_FREE_VMEMMAP,
* so add a BUILD_BUG_ON to catch invalid usage of the tail struct page.
*/
BUILD_BUG_ON(__NR_USED_SUBPAGE >=
RESERVE_VMEMMAP_SIZE / sizeof(struct page));
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);
}

10
mm/hugetlb_vmemmap.h
View File

@ -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;