[PATCH v4 02/11 fix] fix: mm: userfaultfd: recheck dst_pmd entry in move_pages_pte()

[Qi Zheng]

The following WARN_ON_ONCE()s can also be expected to be triggered, so
remove them as well.

if (WARN_ON_ONCE(pmd_none(*dst_pmd)) ||  WARN_ON_ONCE(pmd_none(*src_pmd)) ||
    WARN_ON_ONCE(pmd_trans_huge(*dst_pmd)) || WARN_ON_ONCE(pmd_trans_huge(*src_pmd))

Signed-off-by: Qi Zheng <zhengqi.arch@xxxxxxxxxxxxx>
---
 mm/userfaultfd.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/mm/userfaultfd.c b/mm/userfaultfd.c
index bc9a66ec6a6e4..4527c385935be 100644
--- a/mm/userfaultfd.c
+++ b/mm/userfaultfd.c
@@ -1185,8 +1185,8 @@ static int move_pages_pte(struct mm_struct *mm, pmd_t *dst_pmd, pmd_t *src_pmd,
 	}
 
 	/* Sanity checks before the operation */
-	if (WARN_ON_ONCE(pmd_none(*dst_pmd)) ||	WARN_ON_ONCE(pmd_none(*src_pmd)) ||
-	    WARN_ON_ONCE(pmd_trans_huge(*dst_pmd)) || WARN_ON_ONCE(pmd_trans_huge(*src_pmd))) {
+	if (pmd_none(*dst_pmd) || pmd_none(*src_pmd) ||
+	    pmd_trans_huge(*dst_pmd) || pmd_trans_huge(*src_pmd)) {
 		err = -EINVAL;
 		goto out;
 	}
-- 
2.20.1