[PATCH 4.9 097/171] mm/frame_vector.c: release a semaphore in get_vaddr_frames()

[Greg Kroah-Hartman]

4.9-stable review patch.  If anyone has any objections, please let me know.

------------------

[ Upstream commit 1f704fd0d14043e76e80f6b8b2251b9b2cedcca6 ]

A semaphore is acquired before this check, so we must release it before
leaving.

Link: http://lkml.kernel.org/r/20171211211009.4971-1-christophe.jaillet@xxxxxxxxxx
Fixes: b7f0554a56f2 ("mm: fail get_vaddr_frames() for filesystem-dax mappings")
Signed-off-by: Christophe JAILLET <christophe.jaillet@xxxxxxxxxx>
Acked-by: Michal Hocko <mhocko@xxxxxxxx>
Cc: Dan Williams <dan.j.williams@xxxxxxxxx>
Cc: Christian Borntraeger <borntraeger@xxxxxxxxxx>
Cc: David Sterba <dsterba@xxxxxxxx>
Cc: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
Signed-off-by: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
---
 mm/frame_vector.c | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/mm/frame_vector.c b/mm/frame_vector.c
index 375a103d7a56..d73eed0443f6 100644
--- a/mm/frame_vector.c
+++ b/mm/frame_vector.c
@@ -61,8 +61,10 @@ int get_vaddr_frames(unsigned long start, unsigned int nr_frames,
 	 * get_user_pages_longterm() and disallow it for filesystem-dax
 	 * mappings.
 	 */
-	if (vma_is_fsdax(vma))
-		return -EOPNOTSUPP;
+	if (vma_is_fsdax(vma)) {
+		ret = -EOPNOTSUPP;
+		goto out;
+	}
 
 	if (!(vma->vm_flags & (VM_IO | VM_PFNMAP))) {
 		vec->got_ref = true;
-- 
2.17.1