IB/core: Fix mismatch between locked and pinned pages

Commit bc3e53f ("mm: distinguish between mlocked and pinned
pages") introduced a separate counter for pinned pages and used it in
the IB stack.  However, in ib_umem_get() the pinned counter is
incremented, but ib_umem_release() wrongly decrements the locked
counter.  Fix this.

Signed-off-by: Yishai Hadas <yishaih@mellanox.com>
Reviewed-by: Christoph Lameter <cl@linux.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Roland Dreier <roland@purestorage.com>

drivers/infiniband/core/umem.c

@@ -269,7 +269,7 @@ void ib_umem_release(struct ib_umem *umem)
 	} else
 		down_write(&mm->mmap_sem);
 
-	current->mm->locked_vm -= diff;
+	current->mm->pinned_vm -= diff;
 	up_write(&mm->mmap_sem);
 	mmput(mm);
 	kfree(umem);