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Thu, 19 Nov 2020 22:47:36 -0800 (PST) From: Muchun Song To: corbet@lwn.net, mike.kravetz@oracle.com, tglx@linutronix.de, mingo@redhat.com, bp@alien8.de, x86@kernel.org, hpa@zytor.com, dave.hansen@linux.intel.com, luto@kernel.org, peterz@infradead.org, viro@zeniv.linux.org.uk, akpm@linux-foundation.org, paulmck@kernel.org, mchehab+huawei@kernel.org, pawan.kumar.gupta@linux.intel.com, rdunlap@infradead.org, oneukum@suse.com, anshuman.khandual@arm.com, jroedel@suse.de, almasrymina@google.com, rientjes@google.com, willy@infradead.org, osalvador@suse.de, mhocko@suse.com, song.bao.hua@hisilicon.com Cc: duanxiongchun@bytedance.com, linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org, linux-fsdevel@vger.kernel.org, Muchun Song Subject: [PATCH v5 09/21] mm/hugetlb: Free the vmemmap pages associated with each hugetlb page Date: Fri, 20 Nov 2020 14:43:13 +0800 Message-Id: <20201120064325.34492-10-songmuchun@bytedance.com> X-Mailer: git-send-email 2.21.0 (Apple Git-122) In-Reply-To: <20201120064325.34492-1-songmuchun@bytedance.com> References: <20201120064325.34492-1-songmuchun@bytedance.com> MIME-Version: 1.0 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: When we allocate a hugetlb page from the buddy, we should free the unused vmemmap pages associated with it. We can do that in the prep_new_huge_page(). Signed-off-by: Muchun Song --- arch/x86/include/asm/hugetlb.h | 9 ++ arch/x86/include/asm/pgtable_64_types.h | 8 ++ mm/hugetlb.c | 16 +++ mm/hugetlb_vmemmap.c | 188 ++++++++++++++++++++++++++++++++ mm/hugetlb_vmemmap.h | 5 + 5 files changed, 226 insertions(+) diff --git a/arch/x86/include/asm/hugetlb.h b/arch/x86/include/asm/hugetlb.h index 1721b1aadeb1..c601fe042832 100644 --- a/arch/x86/include/asm/hugetlb.h +++ b/arch/x86/include/asm/hugetlb.h @@ -4,6 +4,15 @@ #include #include +#include + +#ifdef CONFIG_HUGETLB_PAGE_FREE_VMEMMAP +#define vmemmap_pmd_huge vmemmap_pmd_huge +static inline bool vmemmap_pmd_huge(pmd_t *pmd) +{ + return pmd_large(*pmd); +} +#endif #define hugepages_supported() boot_cpu_has(X86_FEATURE_PSE) diff --git a/arch/x86/include/asm/pgtable_64_types.h b/arch/x86/include/asm/pgtable_64_types.h index 52e5f5f2240d..bedbd2e7d06c 100644 --- a/arch/x86/include/asm/pgtable_64_types.h +++ b/arch/x86/include/asm/pgtable_64_types.h @@ -139,6 +139,14 @@ extern unsigned int ptrs_per_p4d; # define VMEMMAP_START __VMEMMAP_BASE_L4 #endif /* CONFIG_DYNAMIC_MEMORY_LAYOUT */ +/* + * VMEMMAP_SIZE - allows the whole linear region to be covered by + * a struct page array. + */ +#define VMEMMAP_SIZE (1UL << (__VIRTUAL_MASK_SHIFT - PAGE_SHIFT - \ + 1 + ilog2(sizeof(struct page)))) +#define VMEMMAP_END (VMEMMAP_START + VMEMMAP_SIZE) + #define VMALLOC_END (VMALLOC_START + (VMALLOC_SIZE_TB << 40) - 1) #define MODULES_VADDR (__START_KERNEL_map + KERNEL_IMAGE_SIZE) diff --git a/mm/hugetlb.c b/mm/hugetlb.c index f88032c24667..a0ce6f33a717 100644 --- a/mm/hugetlb.c +++ b/mm/hugetlb.c @@ -1499,6 +1499,14 @@ void free_huge_page(struct page *page) static void prep_new_huge_page(struct hstate *h, struct page *page, int nid) { + free_huge_page_vmemmap(h, page); + /* + * Because we store preallocated pages on @page->lru, + * vmemmap_pgtable_free() must be called before the + * initialization of @page->lru in INIT_LIST_HEAD(). + */ + vmemmap_pgtable_free(page); + INIT_LIST_HEAD(&page->lru); set_compound_page_dtor(page, HUGETLB_PAGE_DTOR); set_hugetlb_cgroup(page, NULL); @@ -1751,6 +1759,14 @@ static struct page *alloc_fresh_huge_page(struct hstate *h, if (!page) return NULL; + if (vmemmap_pgtable_prealloc(h, page)) { + if (hstate_is_gigantic(h)) + free_gigantic_page(page, huge_page_order(h)); + else + put_page(page); + return NULL; + } + if (hstate_is_gigantic(h)) prep_compound_gigantic_page(page, huge_page_order(h)); prep_new_huge_page(h, page, page_to_nid(page)); diff --git a/mm/hugetlb_vmemmap.c b/mm/hugetlb_vmemmap.c index bc8546df4a51..6f8a735e0dd3 100644 --- a/mm/hugetlb_vmemmap.c +++ b/mm/hugetlb_vmemmap.c @@ -102,6 +102,7 @@ #include #include #include +#include #include #include "hugetlb_vmemmap.h" @@ -114,6 +115,8 @@ * these page frames. Therefore, we need to reserve two pages as vmemmap areas. */ #define RESERVE_VMEMMAP_NR 2U +#define RESERVE_VMEMMAP_SIZE (RESERVE_VMEMMAP_NR << PAGE_SHIFT) +#define TAIL_PAGE_REUSE -1 #ifndef VMEMMAP_HPAGE_SHIFT #define VMEMMAP_HPAGE_SHIFT HPAGE_SHIFT @@ -123,6 +126,21 @@ #define VMEMMAP_HPAGE_SIZE ((1UL) << VMEMMAP_HPAGE_SHIFT) #define VMEMMAP_HPAGE_MASK (~(VMEMMAP_HPAGE_SIZE - 1)) +#define vmemmap_hpage_addr_end(addr, end) \ +({ \ + unsigned long __boundary; \ + __boundary = ((addr) + VMEMMAP_HPAGE_SIZE) & VMEMMAP_HPAGE_MASK; \ + (__boundary - 1 < (end) - 1) ? __boundary : (end); \ +}) + +#ifndef vmemmap_pmd_huge +#define vmemmap_pmd_huge vmemmap_pmd_huge +static inline bool vmemmap_pmd_huge(pmd_t *pmd) +{ + return pmd_huge(*pmd); +} +#endif + static inline unsigned int free_vmemmap_pages_per_hpage(struct hstate *h) { return h->nr_free_vmemmap_pages; @@ -189,6 +207,176 @@ int vmemmap_pgtable_prealloc(struct hstate *h, struct page *page) return -ENOMEM; } +/* + * Walk a vmemmap address to the pmd it maps. + */ +static pmd_t *vmemmap_to_pmd(unsigned long page) +{ + pgd_t *pgd; + p4d_t *p4d; + pud_t *pud; + pmd_t *pmd; + + if (page < VMEMMAP_START || page >= VMEMMAP_END) + return NULL; + + pgd = pgd_offset_k(page); + if (pgd_none(*pgd)) + return NULL; + p4d = p4d_offset(pgd, page); + if (p4d_none(*p4d)) + return NULL; + pud = pud_offset(p4d, page); + + if (pud_none(*pud) || pud_bad(*pud)) + return NULL; + pmd = pmd_offset(pud, page); + + return pmd; +} + +static inline spinlock_t *vmemmap_pmd_lock(pmd_t *pmd) +{ + return pmd_lock(&init_mm, pmd); +} + +static inline int freed_vmemmap_hpage(struct page *page) +{ + return atomic_read(&page->_mapcount) + 1; +} + +static inline int freed_vmemmap_hpage_inc(struct page *page) +{ + return atomic_inc_return_relaxed(&page->_mapcount) + 1; +} + +static inline int freed_vmemmap_hpage_dec(struct page *page) +{ + return atomic_dec_return_relaxed(&page->_mapcount) + 1; +} + +static inline void free_vmemmap_page_list(struct list_head *list) +{ + struct page *page, *next; + + list_for_each_entry_safe(page, next, list, lru) { + list_del(&page->lru); + free_vmemmap_page(page); + } +} + +static void __free_huge_page_pte_vmemmap(struct page *reuse, pte_t *ptep, + unsigned long start, + unsigned long end, + struct list_head *free_pages) +{ + /* Make the tail pages are mapped read-only. */ + pgprot_t pgprot = PAGE_KERNEL_RO; + pte_t entry = mk_pte(reuse, pgprot); + unsigned long addr; + + for (addr = start; addr < end; addr += PAGE_SIZE, ptep++) { + struct page *page; + pte_t old = *ptep; + + VM_WARN_ON(!pte_present(old)); + page = pte_page(old); + list_add(&page->lru, free_pages); + + set_pte_at(&init_mm, addr, ptep, entry); + } +} + +static void __free_huge_page_pmd_vmemmap(struct hstate *h, pmd_t *pmd, + unsigned long addr, + struct list_head *free_pages) +{ + unsigned long next; + unsigned long start = addr + RESERVE_VMEMMAP_SIZE; + unsigned long end = addr + vmemmap_pages_size_per_hpage(h); + struct page *reuse = NULL; + + addr = start; + do { + pte_t *ptep; + + ptep = pte_offset_kernel(pmd, addr); + if (!reuse) + reuse = pte_page(ptep[TAIL_PAGE_REUSE]); + + next = vmemmap_hpage_addr_end(addr, end); + __free_huge_page_pte_vmemmap(reuse, ptep, addr, next, + free_pages); + } while (pmd++, addr = next, addr != end); + + flush_tlb_kernel_range(start, end); +} + +static void split_vmemmap_pmd(pmd_t *pmd, pte_t *pte_p, unsigned long addr) +{ + int i; + pgprot_t pgprot = PAGE_KERNEL; + struct mm_struct *mm = &init_mm; + struct page *page; + pmd_t old_pmd, _pmd; + + old_pmd = READ_ONCE(*pmd); + page = pmd_page(old_pmd); + pmd_populate_kernel(mm, &_pmd, pte_p); + + for (i = 0; i < VMEMMAP_HPAGE_NR; i++, addr += PAGE_SIZE) { + pte_t entry, *pte; + + entry = mk_pte(page + i, pgprot); + pte = pte_offset_kernel(&_pmd, addr); + VM_BUG_ON(!pte_none(*pte)); + set_pte_at(mm, addr, pte, entry); + } + + /* make pte visible before pmd */ + smp_wmb(); + pmd_populate_kernel(mm, pmd, pte_p); +} + +static void split_vmemmap_huge_page(struct page *head, pmd_t *pmd) +{ + struct page *pte_page, *t_page; + unsigned long start = (unsigned long)head & VMEMMAP_HPAGE_MASK; + unsigned long addr = start; + + list_for_each_entry_safe(pte_page, t_page, &head->lru, lru) { + list_del(&pte_page->lru); + VM_BUG_ON(freed_vmemmap_hpage(pte_page)); + split_vmemmap_pmd(pmd++, page_to_virt(pte_page), addr); + addr += VMEMMAP_HPAGE_SIZE; + } + + flush_tlb_kernel_range(start, addr); +} + +void free_huge_page_vmemmap(struct hstate *h, struct page *head) +{ + pmd_t *pmd; + spinlock_t *ptl; + LIST_HEAD(free_pages); + + if (!free_vmemmap_pages_per_hpage(h)) + return; + + pmd = vmemmap_to_pmd((unsigned long)head); + BUG_ON(!pmd); + + ptl = vmemmap_pmd_lock(pmd); + if (vmemmap_pmd_huge(pmd)) + split_vmemmap_huge_page(head, pmd); + + __free_huge_page_pmd_vmemmap(h, pmd, (unsigned long)head, &free_pages); + freed_vmemmap_hpage_inc(pmd_page(*pmd)); + spin_unlock(ptl); + + free_vmemmap_page_list(&free_pages); +} + void __init hugetlb_vmemmap_init(struct hstate *h) { unsigned int order = huge_page_order(h); diff --git a/mm/hugetlb_vmemmap.h b/mm/hugetlb_vmemmap.h index 9eca6879c0a4..a9425d94ed8b 100644 --- a/mm/hugetlb_vmemmap.h +++ b/mm/hugetlb_vmemmap.h @@ -14,6 +14,7 @@ void __init hugetlb_vmemmap_init(struct hstate *h); int vmemmap_pgtable_prealloc(struct hstate *h, struct page *page); void vmemmap_pgtable_free(struct page *page); +void free_huge_page_vmemmap(struct hstate *h, struct page *head); #else static inline void hugetlb_vmemmap_init(struct hstate *h) { @@ -27,5 +28,9 @@ static inline int vmemmap_pgtable_prealloc(struct hstate *h, struct page *page) static inline void vmemmap_pgtable_free(struct page *page) { } + +static inline void free_huge_page_vmemmap(struct hstate *h, struct page *head) +{ +} #endif /* CONFIG_HUGETLB_PAGE_FREE_VMEMMAP */ #endif /* _LINUX_HUGETLB_VMEMMAP_H */