From: "Aneesh Kumar K.V" <aneesh.kumar@xxxxxxxxxxxxxxxxxx> Subject: mm/follow_page_mask: split follow_page_mask to smaller functions. Makes code reading easy. No functional changes in this patch. In a followup patch, we will be updating the follow_page_mask to handle hugetlb hugepd format so that archs like ppc64 can switch to the generic version. This split helps in doing that nicely. Link: http://lkml.kernel.org/r/1494926612-23928-3-git-send-email-aneesh.kumar@xxxxxxxxxxxxxxxxxx Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@xxxxxxxxxxxxxxxxxx> Reviewed-by: Naoya Horiguchi <n-horiguchi@xxxxxxxxxxxxx> Cc: Anshuman Khandual <khandual@xxxxxxxxxxxxxxxxxx> Cc: Michael Ellerman <mpe@xxxxxxxxxxxxxx> Cc: Benjamin Herrenschmidt <benh@xxxxxxxxxxxxxxxxxxx> Cc: Mike Kravetz <kravetz@xxxxxxxxxx> Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> --- mm/gup.c | 148 ++++++++++++++++++++++++++++++++--------------------- 1 file changed, 91 insertions(+), 57 deletions(-) diff -puN mm/gup.c~mm-follow_page_mask-split-follow_page_mask-to-smaller-functions mm/gup.c --- a/mm/gup.c~mm-follow_page_mask-split-follow_page_mask-to-smaller-functions +++ a/mm/gup.c @@ -208,68 +208,16 @@ no_page: return no_page_table(vma, flags); } -/** - * follow_page_mask - look up a page descriptor from a user-virtual address - * @vma: vm_area_struct mapping @address - * @address: virtual address to look up - * @flags: flags modifying lookup behaviour - * @page_mask: on output, *page_mask is set according to the size of the page - * - * @flags can have FOLL_ flags set, defined in <linux/mm.h> - * - * Returns the mapped (struct page *), %NULL if no mapping exists, or - * an error pointer if there is a mapping to something not represented - * by a page descriptor (see also vm_normal_page()). - */ -struct page *follow_page_mask(struct vm_area_struct *vma, - unsigned long address, unsigned int flags, - unsigned int *page_mask) +static struct page *follow_pmd_mask(struct vm_area_struct *vma, + unsigned long address, pud_t *pudp, + unsigned int flags, unsigned int *page_mask) { - pgd_t *pgd; - p4d_t *p4d; - pud_t *pud; pmd_t *pmd; spinlock_t *ptl; struct page *page; struct mm_struct *mm = vma->vm_mm; - *page_mask = 0; - - page = follow_huge_addr(mm, address, flags & FOLL_WRITE); - if (!IS_ERR(page)) { - BUG_ON(flags & FOLL_GET); - return page; - } - - pgd = pgd_offset(mm, address); - if (pgd_none(*pgd) || unlikely(pgd_bad(*pgd))) - return no_page_table(vma, flags); - p4d = p4d_offset(pgd, address); - if (p4d_none(*p4d)) - return no_page_table(vma, flags); - BUILD_BUG_ON(p4d_huge(*p4d)); - if (unlikely(p4d_bad(*p4d))) - return no_page_table(vma, flags); - pud = pud_offset(p4d, address); - if (pud_none(*pud)) - return no_page_table(vma, flags); - if (pud_huge(*pud) && vma->vm_flags & VM_HUGETLB) { - page = follow_huge_pud(mm, address, pud, flags); - if (page) - return page; - return no_page_table(vma, flags); - } - if (pud_devmap(*pud)) { - ptl = pud_lock(mm, pud); - page = follow_devmap_pud(vma, address, pud, flags); - spin_unlock(ptl); - if (page) - return page; - } - if (unlikely(pud_bad(*pud))) - return no_page_table(vma, flags); - - pmd = pmd_offset(pud, address); + pmd = pmd_offset(pudp, address); if (pmd_none(*pmd)) return no_page_table(vma, flags); if (pmd_huge(*pmd) && vma->vm_flags & VM_HUGETLB) { @@ -319,13 +267,99 @@ struct page *follow_page_mask(struct vm_ return ret ? ERR_PTR(ret) : follow_page_pte(vma, address, pmd, flags); } - page = follow_trans_huge_pmd(vma, address, pmd, flags); spin_unlock(ptl); *page_mask = HPAGE_PMD_NR - 1; return page; } + +static struct page *follow_pud_mask(struct vm_area_struct *vma, + unsigned long address, p4d_t *p4dp, + unsigned int flags, unsigned int *page_mask) +{ + pud_t *pud; + spinlock_t *ptl; + struct page *page; + struct mm_struct *mm = vma->vm_mm; + + pud = pud_offset(p4dp, address); + if (pud_none(*pud)) + return no_page_table(vma, flags); + if (pud_huge(*pud) && vma->vm_flags & VM_HUGETLB) { + page = follow_huge_pud(mm, address, pud, flags); + if (page) + return page; + return no_page_table(vma, flags); + } + if (pud_devmap(*pud)) { + ptl = pud_lock(mm, pud); + page = follow_devmap_pud(vma, address, pud, flags); + spin_unlock(ptl); + if (page) + return page; + } + if (unlikely(pud_bad(*pud))) + return no_page_table(vma, flags); + + return follow_pmd_mask(vma, address, pud, flags, page_mask); +} + + +static struct page *follow_p4d_mask(struct vm_area_struct *vma, + unsigned long address, pgd_t *pgdp, + unsigned int flags, unsigned int *page_mask) +{ + p4d_t *p4d; + + p4d = p4d_offset(pgdp, address); + if (p4d_none(*p4d)) + return no_page_table(vma, flags); + BUILD_BUG_ON(p4d_huge(*p4d)); + if (unlikely(p4d_bad(*p4d))) + return no_page_table(vma, flags); + + return follow_pud_mask(vma, address, p4d, flags, page_mask); +} + +/** + * follow_page_mask - look up a page descriptor from a user-virtual address + * @vma: vm_area_struct mapping @address + * @address: virtual address to look up + * @flags: flags modifying lookup behaviour + * @page_mask: on output, *page_mask is set according to the size of the page + * + * @flags can have FOLL_ flags set, defined in <linux/mm.h> + * + * Returns the mapped (struct page *), %NULL if no mapping exists, or + * an error pointer if there is a mapping to something not represented + * by a page descriptor (see also vm_normal_page()). + */ +struct page *follow_page_mask(struct vm_area_struct *vma, + unsigned long address, unsigned int flags, + unsigned int *page_mask) +{ + pgd_t *pgd; + struct page *page; + struct mm_struct *mm = vma->vm_mm; + + *page_mask = 0; + + /* make this handle hugepd */ + page = follow_huge_addr(mm, address, flags & FOLL_WRITE); + if (!IS_ERR(page)) { + BUG_ON(flags & FOLL_GET); + return page; + } + + pgd = pgd_offset(mm, address); + + if (pgd_none(*pgd) || unlikely(pgd_bad(*pgd))) + return no_page_table(vma, flags); + + return follow_p4d_mask(vma, address, pgd, flags, page_mask); +} + static int get_gate_page(struct mm_struct *mm, unsigned long address, unsigned int gup_flags, struct vm_area_struct **vma, struct page **page) _ -- To unsubscribe from this list: send the line "unsubscribe mm-commits" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
