linux-kernel - [PATCH v2] maple_tree: Make maple state reusable after mas_empty

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Date:   Fri,  5 May 2023 22:58:29 +0800
From:   Peng Zhang <zhangpeng.00@...edance.com>
To:     Liam.Howlett@...cle.com
Cc:     akpm@...ux-foundation.org, linux-mm@...ck.org,
        linux-kernel@...r.kernel.org, maple-tree@...ts.infradead.org,
        Peng Zhang <zhangpeng.00@...edance.com>,
        "Edgecombe, Rick P" <rick.p.edgecombe@...el.com>,
        Tad <support@...tco.us>,
        Michael Keyes <mgkeyes@...ovproductions.net>,
        Stable@...r.kernel.org
Subject: [PATCH v2] maple_tree: Make maple state reusable after mas_empty_area()

Make mas->min and mas->max point to a node range instead of a leaf entry
range. This allows mas to still be usable after mas_empty_area() returns.
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@...el.com>
Reported-by: Tad <support@...tco.us>
Reported-by: Michael Keyes <mgkeyes@...ovproductions.net>
Link: https://lore.kernel.org/linux-mm/32f156ba80010fd97dbaf0a0cdfc84366608624d.camel@intel.com/
Link: https://lore.kernel.org/linux-mm/e6108286ac025c268964a7ead3aab9899f9bc6e9.camel@spotco.us/
Fixes: 54a611b60590 ("Maple Tree: add new data structure")
Cc: <Stable@...r.kernel.org>
Signed-off-by: Peng Zhang <zhangpeng.00@...edance.com>
---
 lib/maple_tree.c | 12 +++---------
 1 file changed, 3 insertions(+), 9 deletions(-)

diff --git a/lib/maple_tree.c b/lib/maple_tree.c
index 110a36479dced..8ebc43d4cc8c5 100644
--- a/lib/maple_tree.c
+++ b/lib/maple_tree.c
@@ -5317,15 +5317,9 @@ int mas_empty_area(struct ma_state *mas, unsigned long min,
 
 	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;
-
+	min = mas_safe_min(mas, pivots, offset);
+	if (mas->index < min)
+		mas->index = min;
 	mas->last = mas->index + size - 1;
 	return 0;
 }
-- 
2.20.1