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-rw-r--r--mm/hugetlb.c14
1 files changed, 12 insertions, 2 deletions
diff --git a/mm/hugetlb.c b/mm/hugetlb.c
index 470f7b5b437e..5560b50876fb 100644
--- a/mm/hugetlb.c
+++ b/mm/hugetlb.c
@@ -4889,10 +4889,20 @@ int hugetlb_mcopy_atomic_pte(struct mm_struct *dst_mm,
if (!page)
goto out;
} else if (!*pagep) {
- ret = -ENOMEM;
+ /* If a page already exists, then it's UFFDIO_COPY for
+ * a non-missing case. Return -EEXIST.
+ */
+ if (vm_shared &&
+ hugetlbfs_pagecache_present(h, dst_vma, dst_addr)) {
+ ret = -EEXIST;
+ goto out;
+ }
+
page = alloc_huge_page(dst_vma, dst_addr, 0);
- if (IS_ERR(page))
+ if (IS_ERR(page)) {
+ ret = -ENOMEM;
goto out;
+ }
ret = copy_huge_page_from_user(page,
(const void __user *) src_addr,