From 1c9e8def43a3452e7af658b340f5f4f4ecde5c38 Mon Sep 17 00:00:00 2001 From: Mike Kravetz Date: Wed, 22 Feb 2017 15:43:43 -0800 Subject: userfaultfd: hugetlbfs: add UFFDIO_COPY support for shared mappings When userfaultfd hugetlbfs support was originally added, it followed the pattern of anon mappings and did not support any vmas marked VM_SHARED. As such, support was only added for private mappings. Remove this limitation and support shared mappings. The primary functional change required is adding pages to the page cache. More subtle changes are required for huge page reservation handling in error paths. A lengthy comment in the code describes the reservation handling. [mike.kravetz@oracle.com: update] Link: http://lkml.kernel.org/r/c9c8cafe-baa7-05b4-34ea-1dfa5523a85f@oracle.com Link: http://lkml.kernel.org/r/1487195210-12839-1-git-send-email-mike.kravetz@oracle.com Signed-off-by: Mike Kravetz Reviewed-by: Andrea Arcangeli Cc: Andrew Morton Cc: Mike Rapoport Cc: "Dr. David Alan Gilbert" Cc: Hillf Danton Cc: Mike Kravetz Cc: Pavel Emelyanov Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- mm/hugetlb.c | 26 ++++++++++++++++++++++++-- 1 file changed, 24 insertions(+), 2 deletions(-) (limited to 'mm/hugetlb.c') diff --git a/mm/hugetlb.c b/mm/hugetlb.c index f6c7ff316daf..30e7709a5121 100644 --- a/mm/hugetlb.c +++ b/mm/hugetlb.c @@ -3992,6 +3992,7 @@ int hugetlb_mcopy_atomic_pte(struct mm_struct *dst_mm, unsigned long src_addr, struct page **pagep) { + int vm_shared = dst_vma->vm_flags & VM_SHARED; struct hstate *h = hstate_vma(dst_vma); pte_t _dst_pte; spinlock_t *ptl; @@ -4028,6 +4029,18 @@ int hugetlb_mcopy_atomic_pte(struct mm_struct *dst_mm, __SetPageUptodate(page); set_page_huge_active(page); + /* + * If shared, add to page cache + */ + if (vm_shared) { + struct address_space *mapping = dst_vma->vm_file->f_mapping; + pgoff_t idx = vma_hugecache_offset(h, dst_vma, dst_addr); + + ret = huge_add_to_page_cache(page, mapping, idx); + if (ret) + goto out_release_nounlock; + } + ptl = huge_pte_lockptr(h, dst_mm, dst_pte); spin_lock(ptl); @@ -4035,8 +4048,12 @@ int hugetlb_mcopy_atomic_pte(struct mm_struct *dst_mm, if (!huge_pte_none(huge_ptep_get(dst_pte))) goto out_release_unlock; - ClearPagePrivate(page); - hugepage_add_new_anon_rmap(page, dst_vma, dst_addr); + if (vm_shared) { + page_dup_rmap(page, true); + } else { + ClearPagePrivate(page); + hugepage_add_new_anon_rmap(page, dst_vma, dst_addr); + } _dst_pte = make_huge_pte(dst_vma, page, dst_vma->vm_flags & VM_WRITE); if (dst_vma->vm_flags & VM_WRITE) @@ -4053,11 +4070,16 @@ int hugetlb_mcopy_atomic_pte(struct mm_struct *dst_mm, update_mmu_cache(dst_vma, dst_addr, dst_pte); spin_unlock(ptl); + if (vm_shared) + unlock_page(page); ret = 0; out: return ret; out_release_unlock: spin_unlock(ptl); +out_release_nounlock: + if (vm_shared) + unlock_page(page); put_page(page); goto out; } -- cgit v1.2.3-59-g8ed1b