mm/mempolicy.c: fix wrong sp_node insertion

commit 5ca39575 upstream.

n->end is accessed in sp_insert(). Thus it should be update
before calling sp_insert(). This mistake may make kernel panic.
Signed-off-by: Hillf Danton <dhillf@gmail.com>
Signed-off-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Cc: Sasha Levin <sasha.levin@oracle.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Mel Gorman <mgorman@suse.de>
Cc: Dave Jones <davej@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

mm/mempolicy.c

@@ -2386,8 +2386,8 @@ static int shared_policy_replace(struct shared_policy *sp, unsigned long start,
 				*mpol_new = *n->policy;
 				atomic_set(&mpol_new->refcnt, 1);
 				sp_node_init(n_new, n->end, end, mpol_new);
-				sp_insert(sp, n_new);
 				n->end = start;
+				sp_insert(sp, n_new);
 				n_new = NULL;
 				mpol_new = NULL;
 				break;