From: "Aneesh Kumar K.V" <aneesh.kumar@xxxxxxxxxxxxxxxxxx> Subject: mm/follow_page_mask: add support for hugepage directory entry Architectures like ppc64 supports hugepage size that is not mapped to any of of the page table levels. Instead they add an alternate page table entry format called hugepage directory (hugepd). hugepd indicates that the page table entry maps to a set of hugetlb pages. Add support for this in generic follow_page_mask code. We already support this format in the generic gup code. The default implementation prints warning and returns NULL. We will add ppc64 support in later patches Link: http://lkml.kernel.org/r/1494926612-23928-7-git-send-email-aneesh.kumar@xxxxxxxxxxxxxxxxxx Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@xxxxxxxxxxxxxxxxxx> Cc: Anshuman Khandual <khandual@xxxxxxxxxxxxxxxxxx> Cc: Naoya Horiguchi <n-horiguchi@xxxxxxxxxxxxx> Cc: Michael Ellerman <mpe@xxxxxxxxxxxxxx> Cc: Benjamin Herrenschmidt <benh@xxxxxxxxxxxxxxxxxxx> Cc: Mike Kravetz <kravetz@xxxxxxxxxx> Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> --- include/linux/hugetlb.h | 4 ++++ mm/gup.c | 33 +++++++++++++++++++++++++++++++++ mm/hugetlb.c | 8 ++++++++ 3 files changed, 45 insertions(+) diff -puN include/linux/hugetlb.h~mm-follow_page_mask-add-support-for-hugepage-directory-entry include/linux/hugetlb.h --- a/include/linux/hugetlb.h~mm-follow_page_mask-add-support-for-hugepage-directory-entry +++ a/include/linux/hugetlb.h @@ -141,6 +141,9 @@ pte_t *huge_pte_offset(struct mm_struct int huge_pmd_unshare(struct mm_struct *mm, unsigned long *addr, pte_t *ptep); struct page *follow_huge_addr(struct mm_struct *mm, unsigned long address, int write); +struct page *follow_huge_pd(struct vm_area_struct *vma, + unsigned long address, hugepd_t hpd, + int flags, int pdshift); struct page *follow_huge_pmd(struct mm_struct *mm, unsigned long address, pmd_t *pmd, int flags); struct page *follow_huge_pud(struct mm_struct *mm, unsigned long address, @@ -175,6 +178,7 @@ static inline void hugetlb_report_meminf static inline void hugetlb_show_meminfo(void) { } +#define follow_huge_pd(vma, addr, hpd, flags, pdshift) NULL #define follow_huge_pmd(mm, addr, pmd, flags) NULL #define follow_huge_pud(mm, addr, pud, flags) NULL #define follow_huge_pgd(mm, addr, pgd, flags) NULL diff -puN mm/gup.c~mm-follow_page_mask-add-support-for-hugepage-directory-entry mm/gup.c --- a/mm/gup.c~mm-follow_page_mask-add-support-for-hugepage-directory-entry +++ a/mm/gup.c @@ -226,6 +226,14 @@ static struct page *follow_pmd_mask(stru return page; return no_page_table(vma, flags); } + if (is_hugepd(__hugepd(pmd_val(*pmd)))) { + page = follow_huge_pd(vma, address, + __hugepd(pmd_val(*pmd)), flags, + PMD_SHIFT); + if (page) + return page; + return no_page_table(vma, flags); + } if (pmd_devmap(*pmd)) { ptl = pmd_lock(mm, pmd); page = follow_devmap_pmd(vma, address, pmd, flags); @@ -292,6 +300,14 @@ static struct page *follow_pud_mask(stru return page; return no_page_table(vma, flags); } + if (is_hugepd(__hugepd(pud_val(*pud)))) { + page = follow_huge_pd(vma, address, + __hugepd(pud_val(*pud)), flags, + PUD_SHIFT); + 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); @@ -311,6 +327,7 @@ static struct page *follow_p4d_mask(stru unsigned int flags, unsigned int *page_mask) { p4d_t *p4d; + struct page *page; p4d = p4d_offset(pgdp, address); if (p4d_none(*p4d)) @@ -319,6 +336,14 @@ static struct page *follow_p4d_mask(stru if (unlikely(p4d_bad(*p4d))) return no_page_table(vma, flags); + if (is_hugepd(__hugepd(p4d_val(*p4d)))) { + page = follow_huge_pd(vma, address, + __hugepd(p4d_val(*p4d)), flags, + P4D_SHIFT); + if (page) + return page; + return no_page_table(vma, flags); + } return follow_pud_mask(vma, address, p4d, flags, page_mask); } @@ -362,6 +387,14 @@ struct page *follow_page_mask(struct vm_ if (page) return page; return no_page_table(vma, flags); + } + if (is_hugepd(__hugepd(pgd_val(*pgd)))) { + page = follow_huge_pd(vma, address, + __hugepd(pgd_val(*pgd)), flags, + PGDIR_SHIFT); + if (page) + return page; + return no_page_table(vma, flags); } return follow_p4d_mask(vma, address, pgd, flags, page_mask); diff -puN mm/hugetlb.c~mm-follow_page_mask-add-support-for-hugepage-directory-entry mm/hugetlb.c --- a/mm/hugetlb.c~mm-follow_page_mask-add-support-for-hugepage-directory-entry +++ a/mm/hugetlb.c @@ -4669,6 +4669,14 @@ follow_huge_addr(struct mm_struct *mm, u } struct page * __weak +follow_huge_pd(struct vm_area_struct *vma, + unsigned long address, hugepd_t hpd, int flags, int pdshift) +{ + WARN(1, "hugepd follow called with no support for hugepage directory format\n"); + return NULL; +} + +struct page * __weak follow_huge_pmd(struct mm_struct *mm, unsigned long address, pmd_t *pmd, int flags) { _ -- 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
