Commit 06e8fd99 authored by Liam R. Howlett's avatar Liam R. Howlett Committed by Andrew Morton
Browse files

maple_tree: fix mas_empty_area() search 

The internal function of mas_awalk() was incorrectly skipping the last
entry in a node, which could potentially be NULL.  This is only a problem
for the left-most node in the tree - otherwise that NULL would not exist.

Fix mas_awalk() by using the metadata to obtain the end of the node for
the loop and the logical pivot as apposed to the raw pivot value.

Link: https://lkml.kernel.org/r/20230414145728.4067069-2-Liam.Howlett@oracle.com


Fixes: 54a611b6 ("Maple Tree: add new data structure")
Signed-off-by: default avatarLiam R. Howlett <Liam.Howlett@oracle.com>
Reported-by: default avatarRick Edgecombe <rick.p.edgecombe@intel.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
parent fad8e429

lib/maple_tree.c

+11 −9
Original line number Diff line number Diff line
@@ -5056,10 +5056,10 @@ static inline bool mas_anode_descend(struct ma_state *mas, unsigned long size) 
{

	enum maple_type type = mte_node_type(mas->node);

	unsigned long pivot, min, gap = 0;

	unsigned char offset;

	unsigned long *gaps;

	unsigned long *pivots = ma_pivots(mas_mn(mas), type);

	void __rcu **slots = ma_slots(mas_mn(mas), type);

	unsigned char offset, data_end;

	unsigned long *gaps, *pivots;

	void __rcu **slots;

	struct maple_node *node;

	bool found = false;



	if (ma_is_dense(type)) {
@@ -5067,13 +5067,15 @@ static inline bool mas_anode_descend(struct ma_state *mas, unsigned long size) 
		return true;

	}



	gaps = ma_gaps(mte_to_node(mas->node), type);

	node = mas_mn(mas);

	pivots = ma_pivots(node, type);

	slots = ma_slots(node, type);

	gaps = ma_gaps(node, type);

	offset = mas->offset;

	min = mas_safe_min(mas, pivots, offset);

	for (; offset < mt_slots[type]; offset++) {

		pivot = mas_safe_pivot(mas, pivots, offset, type);

		if (offset && !pivot)

			break;

	data_end = ma_data_end(node, type, pivots, mas->max);

	for (; offset <= data_end; offset++) {

		pivot = mas_logical_pivot(mas, pivots, offset, type);



		/* Not within lower bounds */

		if (mas->index > pivot)