ipc: use new return type vm_fault_t

Use new return type vm_fault_t for fault handler.  For now, this is just
documenting that the function returns a VM_FAULT value rather than an
errno.  Once all instances are converted, vm_fault_t will become a
distinct type.

Commit 1c8f422 ("mm: change return type to vm_fault_t")

Link: http://lkml.kernel.org/r/20180425043413.GA21467@jordon-HP-15-Notebook-PC
Signed-off-by: Souptick Joarder <[email protected]>
Reviewed-by: Matthew Wilcox <[email protected]>
Reviewed-by: Andrew Morton <[email protected]>
Acked-by: Davidlohr Bueso <[email protected]>
Cc: Manfred Spraul <[email protected]>
Cc: Eric W. Biederman <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>

ipc/shm.c

@@ -408,7 +408,7 @@ void exit_shm(struct task_struct *task)
 	up_write(&shm_ids(ns).rwsem);
 }
 
-static int shm_fault(struct vm_fault *vmf)
+static vm_fault_t shm_fault(struct vm_fault *vmf)
 {
 	struct file *file = vmf->vma->vm_file;
 	struct shm_file_data *sfd = shm_file_data(file);