| Message ID | 20200915125947.26204-22-songmuchun@bytedance.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | mm/hugetlb: Free some vmemmap pages of hugetlb page | expand |
On Tue, Sep 15, 2020 at 9:03 PM Muchun Song <songmuchun@bytedance.com> wrote: > > Merge pte to huge pmd if it has ever been split. Now only support > gigantic page which's vmemmap pages size is an integer multiple of > PMD_SIZE. This is the simplest case to handle. > > Signed-off-by: Muchun Song <songmuchun@bytedance.com> > --- > include/linux/hugetlb.h | 7 +++ > mm/hugetlb.c | 104 +++++++++++++++++++++++++++++++++++++++- > 2 files changed, 109 insertions(+), 2 deletions(-) > > diff --git a/include/linux/hugetlb.h b/include/linux/hugetlb.h > index e3aa192f1c39..c56df0da7ae5 100644 > --- a/include/linux/hugetlb.h > +++ b/include/linux/hugetlb.h > @@ -611,6 +611,13 @@ static inline bool vmemmap_pmd_huge(pmd_t *pmd) > } > #endif > > +#ifndef vmemmap_pmd_mkhuge > +static inline pmd_t vmemmap_pmd_mkhuge(struct page *page) > +{ > + return pmd_mkhuge(mk_pmd(page, PAGE_KERNEL)); > +} > +#endif > + > #ifndef VMEMMAP_HPAGE_SHIFT > #define VMEMMAP_HPAGE_SHIFT PMD_SHIFT > #endif > diff --git a/mm/hugetlb.c b/mm/hugetlb.c > index 28c154679838..3ca36e259b4e 100644 > --- a/mm/hugetlb.c > +++ b/mm/hugetlb.c > @@ -1759,6 +1759,62 @@ static void __remap_huge_page_pte_vmemmap(struct page *reuse, pte_t *ptep, > } > } > > +static void __replace_huge_page_pte_vmemmap(pte_t *ptep, unsigned long start, > + unsigned int nr, struct page *huge, > + struct list_head *free_pages) > +{ > + unsigned long addr; > + unsigned long end = start + (nr << PAGE_SHIFT); > + > + for (addr = start; addr < end; addr += PAGE_SIZE, ptep++) { > + struct page *page; > + pte_t old = *ptep; > + pte_t entry; > + > + prepare_vmemmap_page(huge); > + > + entry = mk_pte(huge++, PAGE_KERNEL); > + 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 replace_huge_page_pmd_vmemmap(pmd_t *pmd, unsigned long start, > + struct page *huge, > + struct list_head *free_pages) > +{ > + unsigned long end = start + VMEMMAP_HPAGE_SIZE; > + > + flush_cache_vunmap(start, end); > + __replace_huge_page_pte_vmemmap(pte_offset_kernel(pmd, start), start, > + VMEMMAP_HPAGE_NR, huge, free_pages); > + flush_tlb_kernel_range(start, end); > +} > + > +static pte_t *merge_vmemmap_pte(pmd_t *pmdp, unsigned long addr) > +{ > + pte_t *pte; > + struct page *page; > + > + pte = pte_offset_kernel(pmdp, addr); > + page = pte_page(*pte); > + set_pmd(pmdp, vmemmap_pmd_mkhuge(page)); > + > + return pte; > +} > + > +static void merge_huge_page_pmd_vmemmap(pmd_t *pmd, unsigned long start, > + struct page *huge, > + struct list_head *free_pages) > +{ > + replace_huge_page_pmd_vmemmap(pmd, start, huge, free_pages); > + pte_free_kernel(&init_mm, merge_vmemmap_pte(pmd, start)); > + flush_tlb_kernel_range(start, start + VMEMMAP_HPAGE_SIZE); > +} > + > static inline void alloc_vmemmap_pages(struct hstate *h, struct list_head *list) > { > int i; > @@ -1772,6 +1828,15 @@ static inline void alloc_vmemmap_pages(struct hstate *h, struct list_head *list) > } > } > > +static inline void dissolve_compound_page(struct page *page, unsigned int order) > +{ > + int i; > + unsigned int nr_pages = 1 << order; > + > + for (i = 1; i < nr_pages; i++) > + set_page_refcounted(page + i); > +} > + > static void alloc_huge_page_vmemmap(struct hstate *h, struct page *head) > { > pmd_t *pmd; > @@ -1791,10 +1856,45 @@ static void alloc_huge_page_vmemmap(struct hstate *h, struct page *head) > __remap_huge_page_pte_vmemmap); > if (!freed_vmemmap_hpage_dec(pmd_page(*pmd)) && pmd_split(pmd)) { > /* > - * Todo: > - * Merge pte to huge pmd if it has ever been split. > + * Merge pte to huge pmd if it has ever been split. Now only > + * support gigantic page which's vmemmap pages size is an > + * integer multiple of PMD_SIZE. This is the simplest case > + * to handle. > */ > clear_pmd_split(pmd); > + > + if (IS_ALIGNED(nr_vmemmap(h), VMEMMAP_HPAGE_NR)) { > + unsigned long addr = (unsigned long)head; > + unsigned long end = addr + nr_vmemmap_size(h); > + > + spin_unlock(ptl); > + > + for (; addr < end; addr += VMEMMAP_HPAGE_SIZE) { > + void *to; > + struct page *page; > + > + page = alloc_pages(GFP_VMEMMAP_PAGE & ~__GFP_NOFAIL, > + VMEMMAP_HPAGE_ORDER); > + if (!page) > + goto out; Here forget to call dissolve_compound_page(). + dissolve_compound_page(page, + VMEMMAP_HPAGE_ORDER); > + > + to = page_to_virt(page); > + memcpy(to, (void *)addr, VMEMMAP_HPAGE_SIZE); > + > + /* > + * Make sure that any data that writes to the > + * @to is made visible to the physical page. > + */ > + flush_kernel_vmap_range(to, VMEMMAP_HPAGE_SIZE); > + > + merge_huge_page_pmd_vmemmap(pmd++, addr, page, > + &remap_pages); > + } > + > +out: > + free_vmemmap_page_list(&remap_pages); > + return; > + } > } > spin_unlock(ptl); > } > -- > 2.20.1 >
diff --git a/include/linux/hugetlb.h b/include/linux/hugetlb.h index e3aa192f1c39..c56df0da7ae5 100644 --- a/include/linux/hugetlb.h +++ b/include/linux/hugetlb.h @@ -611,6 +611,13 @@ static inline bool vmemmap_pmd_huge(pmd_t *pmd) } #endif +#ifndef vmemmap_pmd_mkhuge +static inline pmd_t vmemmap_pmd_mkhuge(struct page *page) +{ + return pmd_mkhuge(mk_pmd(page, PAGE_KERNEL)); +} +#endif + #ifndef VMEMMAP_HPAGE_SHIFT #define VMEMMAP_HPAGE_SHIFT PMD_SHIFT #endif diff --git a/mm/hugetlb.c b/mm/hugetlb.c index 28c154679838..3ca36e259b4e 100644 --- a/mm/hugetlb.c +++ b/mm/hugetlb.c @@ -1759,6 +1759,62 @@ static void __remap_huge_page_pte_vmemmap(struct page *reuse, pte_t *ptep, } } +static void __replace_huge_page_pte_vmemmap(pte_t *ptep, unsigned long start, + unsigned int nr, struct page *huge, + struct list_head *free_pages) +{ + unsigned long addr; + unsigned long end = start + (nr << PAGE_SHIFT); + + for (addr = start; addr < end; addr += PAGE_SIZE, ptep++) { + struct page *page; + pte_t old = *ptep; + pte_t entry; + + prepare_vmemmap_page(huge); + + entry = mk_pte(huge++, PAGE_KERNEL); + 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 replace_huge_page_pmd_vmemmap(pmd_t *pmd, unsigned long start, + struct page *huge, + struct list_head *free_pages) +{ + unsigned long end = start + VMEMMAP_HPAGE_SIZE; + + flush_cache_vunmap(start, end); + __replace_huge_page_pte_vmemmap(pte_offset_kernel(pmd, start), start, + VMEMMAP_HPAGE_NR, huge, free_pages); + flush_tlb_kernel_range(start, end); +} + +static pte_t *merge_vmemmap_pte(pmd_t *pmdp, unsigned long addr) +{ + pte_t *pte; + struct page *page; + + pte = pte_offset_kernel(pmdp, addr); + page = pte_page(*pte); + set_pmd(pmdp, vmemmap_pmd_mkhuge(page)); + + return pte; +} + +static void merge_huge_page_pmd_vmemmap(pmd_t *pmd, unsigned long start, + struct page *huge, + struct list_head *free_pages) +{ + replace_huge_page_pmd_vmemmap(pmd, start, huge, free_pages); + pte_free_kernel(&init_mm, merge_vmemmap_pte(pmd, start)); + flush_tlb_kernel_range(start, start + VMEMMAP_HPAGE_SIZE); +} + static inline void alloc_vmemmap_pages(struct hstate *h, struct list_head *list) { int i; @@ -1772,6 +1828,15 @@ static inline void alloc_vmemmap_pages(struct hstate *h, struct list_head *list) } } +static inline void dissolve_compound_page(struct page *page, unsigned int order) +{ + int i; + unsigned int nr_pages = 1 << order; + + for (i = 1; i < nr_pages; i++) + set_page_refcounted(page + i); +} + static void alloc_huge_page_vmemmap(struct hstate *h, struct page *head) { pmd_t *pmd; @@ -1791,10 +1856,45 @@ static void alloc_huge_page_vmemmap(struct hstate *h, struct page *head) __remap_huge_page_pte_vmemmap); if (!freed_vmemmap_hpage_dec(pmd_page(*pmd)) && pmd_split(pmd)) { /* - * Todo: - * Merge pte to huge pmd if it has ever been split. + * Merge pte to huge pmd if it has ever been split. Now only + * support gigantic page which's vmemmap pages size is an + * integer multiple of PMD_SIZE. This is the simplest case + * to handle. */ clear_pmd_split(pmd); + + if (IS_ALIGNED(nr_vmemmap(h), VMEMMAP_HPAGE_NR)) { + unsigned long addr = (unsigned long)head; + unsigned long end = addr + nr_vmemmap_size(h); + + spin_unlock(ptl); + + for (; addr < end; addr += VMEMMAP_HPAGE_SIZE) { + void *to; + struct page *page; + + page = alloc_pages(GFP_VMEMMAP_PAGE & ~__GFP_NOFAIL, + VMEMMAP_HPAGE_ORDER); + if (!page) + goto out; + + to = page_to_virt(page); + memcpy(to, (void *)addr, VMEMMAP_HPAGE_SIZE); + + /* + * Make sure that any data that writes to the + * @to is made visible to the physical page. + */ + flush_kernel_vmap_range(to, VMEMMAP_HPAGE_SIZE); + + merge_huge_page_pmd_vmemmap(pmd++, addr, page, + &remap_pages); + } + +out: + free_vmemmap_page_list(&remap_pages); + return; + } } spin_unlock(ptl); }
Merge pte to huge pmd if it has ever been split. Now only support gigantic page which's vmemmap pages size is an integer multiple of PMD_SIZE. This is the simplest case to handle. Signed-off-by: Muchun Song <songmuchun@bytedance.com> --- include/linux/hugetlb.h | 7 +++ mm/hugetlb.c | 104 +++++++++++++++++++++++++++++++++++++++- 2 files changed, 109 insertions(+), 2 deletions(-)