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From:   "Liam R. Howlett" <Liam.Howlett@oracle.com>
To:     Andrew Morton <akpm@linux-foundation.org>
Cc:     linux-mm@kvack.org, linux-kernel@vger.kernel.org,
        maple-tree@lists.infradead.org,
        "Liam R. Howlett" <Liam.Howlett@oracle.com>,
        "Edgecombe, Rick P" <rick.p.edgecombe@intel.com>,
        Tad <support@spotco.us>,
        Michael Keyes <mgkeyes@vigovproductions.net>,
        Stable@vger.kernel.org
Subject: [PATCH] maple_tree: Make maple state reusable after mas_empty_area()
Date:   Thu,  4 May 2023 13:55:09 -0400
Message-Id: <20230504175509.2195838-1-Liam.Howlett@oracle.com>
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Do not update the min and max of the maple state to the slot of the leaf
node.  Leaving the min and max to the node entry allows for the maple
state to be used in other operations.

Users would get unexpected results from other operations on the maple
state after calling the affected function.

Reported-by: "Edgecombe, Rick P" <rick.p.edgecombe@intel.com>
Reported-by: Tad <support@spotco.us>
Reported-by: Michael Keyes <mgkeyes@vigovproductions.net>
Link: https://lore.kernel.org/linux-mm/32f156ba80010fd97dbaf0a0cdfc84366608624d.camel@intel.com/
Link: https://lore.kernel.org/linux-mm/e6108286ac025c268964a7ead3aab9899f9bc6e9.camel@spotco.us/
Fixes: Fixes: 54a611b60590 ("Maple Tree: add new data structure")
Cc: <Stable@vger.kernel.org>
Signed-off-by: Liam R. Howlett <Liam.Howlett@oracle.com>
---
 lib/maple_tree.c | 15 +--------------
 1 file changed, 1 insertion(+), 14 deletions(-)

diff --git a/lib/maple_tree.c b/lib/maple_tree.c
index 110a36479dced..1c4bc7a988ed3 100644
--- a/lib/maple_tree.c
+++ b/lib/maple_tree.c
@@ -5285,10 +5285,6 @@ static inline int mas_sparse_area(struct ma_state *mas, unsigned long min,
 int mas_empty_area(struct ma_state *mas, unsigned long min,
 		unsigned long max, unsigned long size)
 {
-	unsigned char offset;
-	unsigned long *pivots;
-	enum maple_type mt;
-
 	if (min >= max)
 		return -EINVAL;
 
@@ -5311,18 +5307,9 @@ int mas_empty_area(struct ma_state *mas, unsigned long min,
 	if (unlikely(mas_is_err(mas)))
 		return xa_err(mas->node);
 
-	offset = mas->offset;
-	if (unlikely(offset == MAPLE_NODE_SLOTS))
+	if (unlikely(mas->offset == MAPLE_NODE_SLOTS))
 		return -EBUSY;
 
-	mt = mte_node_type(mas->node);
-	pivots = ma_pivots(mas_mn(mas), mt);
-	if (offset)
-		mas->min = pivots[offset - 1] + 1;
-
-	if (offset < mt_pivots[mt])
-		mas->max = pivots[offset];
-
 	if (mas->index < mas->min)
 		mas->index = mas->min;
 
-- 
2.39.2