mm: gup: use get_user_pages_unlocked

This allows those get_user_pages calls to pass FAULT_FLAG_ALLOW_RETRY to
the page fault in order to release the mmap_sem during the I/O.

Signed-off-by: Andrea Arcangeli <aarcange@redhat.com>
Reviewed-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Andres Lagar-Cavilla <andreslc@google.com>
Cc: Peter Feiner <pfeiner@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 2 insertions, 5 deletions

diff --git a/drivers/scsi/st.c b/drivers/scsi/st.c
index 128d3b55bdd9..9a1c34205254 100644
--- a/drivers/scsi/st.c
+++ b/drivers/scsi/st.c
@@ -4551,18 +4551,15 @@ static int sgl_map_user_pages(struct st_buffer *STbp,
                 return -ENOMEM;
 
         /* Try to fault in all of the necessary pages */
-        down_read(&current->mm->mmap_sem);
         /* rw==READ means read from drive, write into memory area */
-        res = get_user_pages(
+        res = get_user_pages_unlocked(
                 current,
                 current->mm,
                 uaddr,
                 nr_pages,
                 rw == READ,
                 0, /* don't force */
-                pages,
-                NULL);
-        up_read(&current->mm->mmap_sem);
+                pages);
 
         /* Errors and no page mapped should return here */
         if (res < nr_pages)