s390/mm/gmap: Fix __gmap_fault() return code

Errors in fixup_user_fault() were masked and -EFAULT was returned for
any error, including out of memory.

Fix this by returning the correct error code. This means that in many
cases the error code will be propagated all the way to userspace.

Suggested-by: Heiko Carstens <hca@linux.ibm.com>
Signed-off-by: Claudio Imbrenda <imbrenda@linux.ibm.com>
Reviewed-by: Heiko Carstens <hca@linux.ibm.com>
Acked-by: Alexander Gordeev <agordeev@linux.ibm.com>
Link: https://lore.kernel.org/r/20241022120601.167009-5-imbrenda@linux.ibm.com
Signed-off-by: Heiko Carstens <hca@linux.ibm.com>

Author: Claudio Imbrenda

arch/s390/mm/gmap.c

@@ -718,13 +718,12 @@ static int __gmap_fault(struct gmap *gmap, unsigned long gaddr, unsigned int fau
 	if (IS_ERR_VALUE(vmaddr))
 		return vmaddr;
 
-	if (fault_flags & FAULT_FLAG_RETRY_NOWAIT) {
+	if (fault_flags & FAULT_FLAG_RETRY_NOWAIT)
 		rc = fixup_user_fault_nowait(gmap->mm, vmaddr, fault_flags, &unlocked);
-		if (rc)
-			return rc;
-	} else if (fixup_user_fault(gmap->mm, vmaddr, fault_flags, &unlocked)) {
-		return -EFAULT;
-	}
+	else
+		rc = fixup_user_fault(gmap->mm, vmaddr, fault_flags, &unlocked);
+	if (rc)
+		return rc;
 	/*
 	 * In the case that fixup_user_fault unlocked the mmap_lock during
 	 * fault-in, redo __gmap_translate() to avoid racing with a