mm/gup: cache dev_pagemap while pinning pages

[muen/linux.git] / mm / huge_memory.c

diff --git a/mm/huge_memory.c b/mm/huge_memory.c
index 8ea1b36bd452d795da8ac2714634c6bc70a45b99..25c7d7509cf49efe4bc29ed811f05df8de9b6a48 100644 (file)
--- a/mm/huge_memory.c
+++ b/mm/huge_memory.c
@@ -852,11 +852,10 @@ static void touch_pmd(struct vm_area_struct *vma, unsigned long addr,
 }
 
 struct page *follow_devmap_pmd(struct vm_area_struct *vma, unsigned long addr,
-               pmd_t *pmd, int flags)
+               pmd_t *pmd, int flags, struct dev_pagemap **pgmap)
 {
        unsigned long pfn = pmd_pfn(*pmd);
        struct mm_struct *mm = vma->vm_mm;
-       struct dev_pagemap *pgmap;
        struct page *page;
 
        assert_spin_locked(pmd_lockptr(mm, pmd));
@@ -886,12 +885,11 @@ struct page *follow_devmap_pmd(struct vm_area_struct *vma, unsigned long addr,
                return ERR_PTR(-EEXIST);
 
        pfn += (addr & ~PMD_MASK) >> PAGE_SHIFT;
-       pgmap = get_dev_pagemap(pfn, NULL);
-       if (!pgmap)
+       *pgmap = get_dev_pagemap(pfn, *pgmap);
+       if (!*pgmap)
                return ERR_PTR(-EFAULT);
        page = pfn_to_page(pfn);
        get_page(page);
-       put_dev_pagemap(pgmap);
 
        return page;
 }
@@ -1000,11 +998,10 @@ static void touch_pud(struct vm_area_struct *vma, unsigned long addr,
 }
 
 struct page *follow_devmap_pud(struct vm_area_struct *vma, unsigned long addr,
-               pud_t *pud, int flags)
+               pud_t *pud, int flags, struct dev_pagemap **pgmap)
 {
        unsigned long pfn = pud_pfn(*pud);
        struct mm_struct *mm = vma->vm_mm;
-       struct dev_pagemap *pgmap;
        struct page *page;
 
        assert_spin_locked(pud_lockptr(mm, pud));
@@ -1028,12 +1025,11 @@ struct page *follow_devmap_pud(struct vm_area_struct *vma, unsigned long addr,
                return ERR_PTR(-EEXIST);
 
        pfn += (addr & ~PUD_MASK) >> PAGE_SHIFT;
-       pgmap = get_dev_pagemap(pfn, NULL);
-       if (!pgmap)
+       *pgmap = get_dev_pagemap(pfn, *pgmap);
+       if (!*pgmap)
                return ERR_PTR(-EFAULT);
        page = pfn_to_page(pfn);
        get_page(page);
-       put_dev_pagemap(pgmap);
 
        return page;
 }