maple_tree: only root node could be deficient

Each level's rightmost node should have (max == ULONG_MAX).  This means
current validation skips the right most node on each level.

Only the root node may be below the minimum data threshold.

Link: https://lkml.kernel.org/r/[email protected]
Signed-off-by: Wei Yang <[email protected]>
Reviewed-by: Liam R. Howlett <[email protected]>
Cc: Sidhartha Kumar <[email protected]>
Cc: Lorenzo Stoakes <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>

lib/maple_tree.c

@@ -7556,7 +7556,7 @@ void mt_validate(struct maple_tree *mt)
 		MAS_WARN_ON(&mas, mte_dead_node(mas.node));
 		end = mas_data_end(&mas);
 		if (MAS_WARN_ON(&mas, (end < mt_min_slot_count(mas.node)) &&
-				(mas.max != ULONG_MAX))) {
+				(!mte_is_root(mas.node)))) {
 			pr_err("Invalid size %u of " PTR_FMT "\n",
 			       end, mas_mn(&mas));
 		}