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authorMuchun Song <songmuchun@bytedance.com>2021-07-01 04:47:33 +0300
committerLinus Torvalds <torvalds@linux-foundation.org>2021-07-01 06:47:25 +0300
commit774905878fc9b0b9a5ee4a889b97f773a077aeee (patch)
treebb20b78fbeb6124481bd69f04a60d0a93b640adc /mm/hugetlb_vmemmap.c
parent4bab4964a59f277915285787c828b810151de7a1 (diff)
downloadlinux-774905878fc9b0b9a5ee4a889b97f773a077aeee.tar.xz
mm: hugetlb: introduce nr_free_vmemmap_pages in the struct hstate
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>
Diffstat (limited to 'mm/hugetlb_vmemmap.c')
-rw-r--r--mm/hugetlb_vmemmap.c33
1 files changed, 33 insertions, 0 deletions
diff --git a/mm/hugetlb_vmemmap.c b/mm/hugetlb_vmemmap.c
index 3070e1465b1b..f9f9bb212319 100644
--- a/mm/hugetlb_vmemmap.c
+++ b/mm/hugetlb_vmemmap.c
@@ -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);
+}