diff options
Diffstat (limited to 'mm/huge_memory.c')
| -rw-r--r-- | mm/huge_memory.c | 27 |
1 files changed, 8 insertions, 19 deletions
diff --git a/mm/huge_memory.c b/mm/huge_memory.c index c468fee595ff..baf4ea6d8e1a 100644 --- a/mm/huge_memory.c +++ b/mm/huge_memory.c @@ -1097,23 +1097,16 @@ int copy_huge_pmd(struct mm_struct *dst_mm, struct mm_struct *src_mm, src_page = pmd_page(pmd); VM_BUG_ON_PAGE(!PageHead(src_page), src_page); - /* - * If this page is a potentially pinned page, split and retry the fault - * with smaller page size. Normally this should not happen because the - * userspace should use MADV_DONTFORK upon pinned regions. This is a - * best effort that the pinned pages won't be replaced by another - * random page during the coming copy-on-write. - */ - if (unlikely(page_needs_cow_for_dma(src_vma, src_page))) { + get_page(src_page); + if (unlikely(page_try_dup_anon_rmap(src_page, true, src_vma))) { + /* Page maybe pinned: split and retry the fault on PTEs. */ + put_page(src_page); pte_free(dst_mm, pgtable); spin_unlock(src_ptl); spin_unlock(dst_ptl); __split_huge_pmd(src_vma, src_pmd, addr, false, NULL); return -EAGAIN; } - - get_page(src_page); - page_dup_rmap(src_page, true); add_mm_counter(dst_mm, MM_ANONPAGES, HPAGE_PMD_NR); out_zero_page: mm_inc_nr_ptes(dst_mm); @@ -1217,14 +1210,10 @@ int copy_huge_pud(struct mm_struct *dst_mm, struct mm_struct *src_mm, /* No huge zero pud yet */ } - /* Please refer to comments in copy_huge_pmd() */ - if (unlikely(page_needs_cow_for_dma(vma, pud_page(pud)))) { - spin_unlock(src_ptl); - spin_unlock(dst_ptl); - __split_huge_pud(vma, src_pud, addr); - return -EAGAIN; - } - + /* + * TODO: once we support anonymous pages, use page_try_dup_anon_rmap() + * and split if duplicating fails. + */ pudp_set_wrprotect(src_mm, addr, src_pud); pud = pud_mkold(pud_wrprotect(pud)); set_pud_at(dst_mm, addr, dst_pud, pud); |