mm/gup: cache dev_pagemap while pinning pages
Getting pages from ZONE_DEVICE memory needs to check the backing device's live-ness, which is tracked in the device's dev_pagemap metadata. This metadata is stored in a radix tree and looking it up adds measurable software overhead. This patch avoids repeating this relatively costly operation when dev_pagemap is used by caching the last dev_pagemap while getting user pages. The gup_benchmark kernel self test reports this reduces time to get user pages to as low as 1/3 of the previous time. Link: http://lkml.kernel.org/r/20181012173040.15669-1-keith.busch@intel.com Signed-off-by: Keith Busch <keith.busch@intel.com> Reviewed-by: Dan Williams <dan.j.williams@intel.com> Acked-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> Cc: Dave Hansen <dave.hansen@intel.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Keith Busch
Linus Torvalds
Родитель
9fd61bc951
Коммит
df06b37ffe
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@ -213,9 +213,9 @@ static inline int hpage_nr_pages(struct page *page)
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}
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struct page *follow_devmap_pmd(struct vm_area_struct *vma, unsigned long addr,
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pmd_t *pmd, int flags);
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pmd_t *pmd, int flags, struct dev_pagemap **pgmap);
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struct page *follow_devmap_pud(struct vm_area_struct *vma, unsigned long addr,
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pud_t *pud, int flags);
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pud_t *pud, int flags, struct dev_pagemap **pgmap);
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extern vm_fault_t do_huge_pmd_numa_page(struct vm_fault *vmf, pmd_t orig_pmd);
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@ -344,13 +344,13 @@ static inline void mm_put_huge_zero_page(struct mm_struct *mm)
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}
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static inline struct page *follow_devmap_pmd(struct vm_area_struct *vma,
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unsigned long addr, pmd_t *pmd, int flags)
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unsigned long addr, pmd_t *pmd, int flags, struct dev_pagemap **pgmap)
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{
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return NULL;
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}
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static inline struct page *follow_devmap_pud(struct vm_area_struct *vma,
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unsigned long addr, pud_t *pud, int flags)
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unsigned long addr, pud_t *pud, int flags, struct dev_pagemap **pgmap)
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{
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return NULL;
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}
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@ -2536,16 +2536,8 @@ static inline vm_fault_t vmf_error(int err)
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return VM_FAULT_SIGBUS;
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}
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struct page *follow_page_mask(struct vm_area_struct *vma,
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unsigned long address, unsigned int foll_flags,
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unsigned int *page_mask);
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static inline struct page *follow_page(struct vm_area_struct *vma,
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unsigned long address, unsigned int foll_flags)
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{
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unsigned int unused_page_mask;
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return follow_page_mask(vma, address, foll_flags, &unused_page_mask);
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}
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struct page *follow_page(struct vm_area_struct *vma, unsigned long address,
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unsigned int foll_flags);
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#define FOLL_WRITE 0x01 /* check pte is writable */
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#define FOLL_TOUCH 0x02 /* mark page accessed */
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110
mm/gup.c
110
mm/gup.c
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@ -20,6 +20,11 @@
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#include "internal.h"
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struct follow_page_context {
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struct dev_pagemap *pgmap;
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unsigned int page_mask;
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};
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static struct page *no_page_table(struct vm_area_struct *vma,
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unsigned int flags)
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{
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@ -71,10 +76,10 @@ static inline bool can_follow_write_pte(pte_t pte, unsigned int flags)
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}
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static struct page *follow_page_pte(struct vm_area_struct *vma,
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unsigned long address, pmd_t *pmd, unsigned int flags)
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unsigned long address, pmd_t *pmd, unsigned int flags,
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struct dev_pagemap **pgmap)
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{
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struct mm_struct *mm = vma->vm_mm;
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struct dev_pagemap *pgmap = NULL;
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struct page *page;
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spinlock_t *ptl;
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pte_t *ptep, pte;
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@ -116,8 +121,8 @@ retry:
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* Only return device mapping pages in the FOLL_GET case since
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* they are only valid while holding the pgmap reference.
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*/
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pgmap = get_dev_pagemap(pte_pfn(pte), NULL);
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if (pgmap)
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*pgmap = get_dev_pagemap(pte_pfn(pte), *pgmap);
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if (*pgmap)
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page = pte_page(pte);
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else
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goto no_page;
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@ -152,15 +157,8 @@ retry:
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goto retry;
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}
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if (flags & FOLL_GET) {
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if (flags & FOLL_GET)
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get_page(page);
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/* drop the pgmap reference now that we hold the page */
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if (pgmap) {
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put_dev_pagemap(pgmap);
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pgmap = NULL;
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}
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}
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if (flags & FOLL_TOUCH) {
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if ((flags & FOLL_WRITE) &&
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!pte_dirty(pte) && !PageDirty(page))
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@ -210,7 +208,8 @@ no_page:
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static struct page *follow_pmd_mask(struct vm_area_struct *vma,
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unsigned long address, pud_t *pudp,
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unsigned int flags, unsigned int *page_mask)
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unsigned int flags,
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struct follow_page_context *ctx)
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{
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pmd_t *pmd, pmdval;
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spinlock_t *ptl;
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@ -258,13 +257,13 @@ retry:
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}
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if (pmd_devmap(pmdval)) {
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ptl = pmd_lock(mm, pmd);
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page = follow_devmap_pmd(vma, address, pmd, flags);
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page = follow_devmap_pmd(vma, address, pmd, flags, &ctx->pgmap);
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spin_unlock(ptl);
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if (page)
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return page;
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}
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if (likely(!pmd_trans_huge(pmdval)))
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return follow_page_pte(vma, address, pmd, flags);
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return follow_page_pte(vma, address, pmd, flags, &ctx->pgmap);
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if ((flags & FOLL_NUMA) && pmd_protnone(pmdval))
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return no_page_table(vma, flags);
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@ -284,7 +283,7 @@ retry_locked:
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}
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if (unlikely(!pmd_trans_huge(*pmd))) {
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spin_unlock(ptl);
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return follow_page_pte(vma, address, pmd, flags);
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return follow_page_pte(vma, address, pmd, flags, &ctx->pgmap);
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}
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if (flags & FOLL_SPLIT) {
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int ret;
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@ -307,18 +306,18 @@ retry_locked:
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}
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return ret ? ERR_PTR(ret) :
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follow_page_pte(vma, address, pmd, flags);
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follow_page_pte(vma, address, pmd, flags, &ctx->pgmap);
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}
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page = follow_trans_huge_pmd(vma, address, pmd, flags);
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spin_unlock(ptl);
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*page_mask = HPAGE_PMD_NR - 1;
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ctx->page_mask = HPAGE_PMD_NR - 1;
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return page;
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}
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static struct page *follow_pud_mask(struct vm_area_struct *vma,
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unsigned long address, p4d_t *p4dp,
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unsigned int flags, unsigned int *page_mask)
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unsigned int flags,
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struct follow_page_context *ctx)
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{
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pud_t *pud;
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spinlock_t *ptl;
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@ -344,7 +343,7 @@ static struct page *follow_pud_mask(struct vm_area_struct *vma,
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}
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if (pud_devmap(*pud)) {
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ptl = pud_lock(mm, pud);
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page = follow_devmap_pud(vma, address, pud, flags);
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page = follow_devmap_pud(vma, address, pud, flags, &ctx->pgmap);
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spin_unlock(ptl);
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if (page)
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return page;
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@ -352,13 +351,13 @@ static struct page *follow_pud_mask(struct vm_area_struct *vma,
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if (unlikely(pud_bad(*pud)))
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return no_page_table(vma, flags);
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return follow_pmd_mask(vma, address, pud, flags, page_mask);
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return follow_pmd_mask(vma, address, pud, flags, ctx);
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}
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static struct page *follow_p4d_mask(struct vm_area_struct *vma,
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unsigned long address, pgd_t *pgdp,
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unsigned int flags, unsigned int *page_mask)
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unsigned int flags,
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struct follow_page_context *ctx)
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{
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p4d_t *p4d;
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struct page *page;
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@ -378,7 +377,7 @@ static struct page *follow_p4d_mask(struct vm_area_struct *vma,
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return page;
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return no_page_table(vma, flags);
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}
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return follow_pud_mask(vma, address, p4d, flags, page_mask);
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return follow_pud_mask(vma, address, p4d, flags, ctx);
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}
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/**
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@ -396,13 +395,13 @@ static struct page *follow_p4d_mask(struct vm_area_struct *vma,
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*/
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struct page *follow_page_mask(struct vm_area_struct *vma,
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unsigned long address, unsigned int flags,
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unsigned int *page_mask)
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struct follow_page_context *ctx)
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{
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pgd_t *pgd;
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struct page *page;
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struct mm_struct *mm = vma->vm_mm;
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*page_mask = 0;
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ctx->page_mask = 0;
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/* make this handle hugepd */
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page = follow_huge_addr(mm, address, flags & FOLL_WRITE);
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@ -431,7 +430,19 @@ struct page *follow_page_mask(struct vm_area_struct *vma,
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return no_page_table(vma, flags);
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}
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return follow_p4d_mask(vma, address, pgd, flags, page_mask);
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return follow_p4d_mask(vma, address, pgd, flags, ctx);
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}
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struct page *follow_page(struct vm_area_struct *vma, unsigned long address,
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unsigned int foll_flags)
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{
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struct follow_page_context ctx = { NULL };
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struct page *page;
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page = follow_page_mask(vma, address, foll_flags, &ctx);
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if (ctx.pgmap)
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put_dev_pagemap(ctx.pgmap);
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return page;
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}
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static int get_gate_page(struct mm_struct *mm, unsigned long address,
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@ -659,9 +670,9 @@ static long __get_user_pages(struct task_struct *tsk, struct mm_struct *mm,
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unsigned int gup_flags, struct page **pages,
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struct vm_area_struct **vmas, int *nonblocking)
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{
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long i = 0;
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unsigned int page_mask;
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long ret = 0, i = 0;
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struct vm_area_struct *vma = NULL;
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struct follow_page_context ctx = { NULL };
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if (!nr_pages)
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return 0;
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@ -691,12 +702,14 @@ static long __get_user_pages(struct task_struct *tsk, struct mm_struct *mm,
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pages ? &pages[i] : NULL);
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if (ret)
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return i ? : ret;
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page_mask = 0;
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ctx.page_mask = 0;
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goto next_page;
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}
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if (!vma || check_vma_flags(vma, gup_flags))
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return i ? : -EFAULT;
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if (!vma || check_vma_flags(vma, gup_flags)) {
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ret = -EFAULT;
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goto out;
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}
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if (is_vm_hugetlb_page(vma)) {
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i = follow_hugetlb_page(mm, vma, pages, vmas,
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&start, &nr_pages, i,
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@ -709,23 +722,26 @@ retry:
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* If we have a pending SIGKILL, don't keep faulting pages and
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* potentially allocating memory.
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*/
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if (unlikely(fatal_signal_pending(current)))
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return i ? i : -ERESTARTSYS;
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if (unlikely(fatal_signal_pending(current))) {
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ret = -ERESTARTSYS;
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goto out;
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}
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cond_resched();
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page = follow_page_mask(vma, start, foll_flags, &page_mask);
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page = follow_page_mask(vma, start, foll_flags, &ctx);
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if (!page) {
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int ret;
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ret = faultin_page(tsk, vma, start, &foll_flags,
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nonblocking);
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switch (ret) {
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case 0:
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goto retry;
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case -EBUSY:
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ret = 0;
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/* FALLTHRU */
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case -EFAULT:
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case -ENOMEM:
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case -EHWPOISON:
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return i ? i : ret;
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case -EBUSY:
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return i;
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goto out;
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case -ENOENT:
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goto next_page;
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}
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@ -737,27 +753,31 @@ retry:
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*/
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goto next_page;
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} else if (IS_ERR(page)) {
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return i ? i : PTR_ERR(page);
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ret = PTR_ERR(page);
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goto out;
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}
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if (pages) {
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pages[i] = page;
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flush_anon_page(vma, page, start);
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flush_dcache_page(page);
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page_mask = 0;
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ctx.page_mask = 0;
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}
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next_page:
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if (vmas) {
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vmas[i] = vma;
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page_mask = 0;
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ctx.page_mask = 0;
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}
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page_increm = 1 + (~(start >> PAGE_SHIFT) & page_mask);
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page_increm = 1 + (~(start >> PAGE_SHIFT) & ctx.page_mask);
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if (page_increm > nr_pages)
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page_increm = nr_pages;
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i += page_increm;
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start += page_increm * PAGE_SIZE;
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nr_pages -= page_increm;
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} while (nr_pages);
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return i;
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out:
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if (ctx.pgmap)
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put_dev_pagemap(ctx.pgmap);
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return i ? i : ret;
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}
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static bool vma_permits_fault(struct vm_area_struct *vma,
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@ -852,11 +852,10 @@ static void touch_pmd(struct vm_area_struct *vma, unsigned long addr,
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}
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struct page *follow_devmap_pmd(struct vm_area_struct *vma, unsigned long addr,
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pmd_t *pmd, int flags)
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pmd_t *pmd, int flags, struct dev_pagemap **pgmap)
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{
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unsigned long pfn = pmd_pfn(*pmd);
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struct mm_struct *mm = vma->vm_mm;
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struct dev_pagemap *pgmap;
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struct page *page;
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assert_spin_locked(pmd_lockptr(mm, pmd));
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@ -886,12 +885,11 @@ struct page *follow_devmap_pmd(struct vm_area_struct *vma, unsigned long addr,
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return ERR_PTR(-EEXIST);
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pfn += (addr & ~PMD_MASK) >> PAGE_SHIFT;
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pgmap = get_dev_pagemap(pfn, NULL);
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if (!pgmap)
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*pgmap = get_dev_pagemap(pfn, *pgmap);
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if (!*pgmap)
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return ERR_PTR(-EFAULT);
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page = pfn_to_page(pfn);
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get_page(page);
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put_dev_pagemap(pgmap);
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return page;
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}
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@ -1000,11 +998,10 @@ static void touch_pud(struct vm_area_struct *vma, unsigned long addr,
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}
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struct page *follow_devmap_pud(struct vm_area_struct *vma, unsigned long addr,
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pud_t *pud, int flags)
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pud_t *pud, int flags, struct dev_pagemap **pgmap)
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{
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unsigned long pfn = pud_pfn(*pud);
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struct mm_struct *mm = vma->vm_mm;
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struct dev_pagemap *pgmap;
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struct page *page;
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assert_spin_locked(pud_lockptr(mm, pud));
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@ -1028,12 +1025,11 @@ struct page *follow_devmap_pud(struct vm_area_struct *vma, unsigned long addr,
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return ERR_PTR(-EEXIST);
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pfn += (addr & ~PUD_MASK) >> PAGE_SHIFT;
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pgmap = get_dev_pagemap(pfn, NULL);
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if (!pgmap)
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*pgmap = get_dev_pagemap(pfn, *pgmap);
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if (!*pgmap)
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return ERR_PTR(-EFAULT);
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page = pfn_to_page(pfn);
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get_page(page);
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put_dev_pagemap(pgmap);
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return page;
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}
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@ -1709,11 +1709,9 @@ SYSCALL_DEFINE5(mremap, unsigned long, addr, unsigned long, old_len,
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return ret;
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}
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struct page *follow_page_mask(struct vm_area_struct *vma,
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unsigned long address, unsigned int flags,
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unsigned int *page_mask)
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struct page *follow_page(struct vm_area_struct *vma, unsigned long address,
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unsigned int foll_flags)
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{
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*page_mask = 0;
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return NULL;
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}
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