linux-kernel - [PATCH v2 5/8] maple_tree: make mas_validate_limits() check root node and node limit

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Message-Id: <20230711035444.526-6-zhangpeng.00@bytedance.com>
Date:   Tue, 11 Jul 2023 11:54:41 +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>
Subject: [PATCH v2 5/8] maple_tree: make mas_validate_limits() check root node and node limit

Update mas_validate_limits() to check root node, check node limit pivot
if there is enough room for it to exist and check data_end. Remove the
check for child existence as it is done in mas_validate_child_slot().

Signed-off-by: Peng Zhang <zhangpeng.00@...edance.com>
---
 lib/maple_tree.c | 30 ++++++++++++++----------------
 1 file changed, 14 insertions(+), 16 deletions(-)

diff --git a/lib/maple_tree.c b/lib/maple_tree.c
index f750ebef595f..072532fa18ee 100644
--- a/lib/maple_tree.c
+++ b/lib/maple_tree.c
@@ -7146,7 +7146,9 @@ static void mas_validate_child_slot(struct ma_state *mas)
 }
 
 /*
- * Validate all pivots are within mas->min and mas->max.
+ * Validate all pivots are within mas->min and mas->max, check metadata ends
+ * where the maximum ends and ensure there is no slots or pivots set outside of
+ * the end of the data.
  */
 static void mas_validate_limits(struct ma_state *mas)
 {
@@ -7156,26 +7158,15 @@ static void mas_validate_limits(struct ma_state *mas)
 	void __rcu **slots = ma_slots(mte_to_node(mas->node), type);
 	unsigned long *pivots = ma_pivots(mas_mn(mas), type);
 
-	/* all limits are fine here. */
-	if (mte_is_root(mas->node))
-		return;
-
 	for (i = 0; i < mt_slots[type]; i++) {
 		unsigned long piv;
 
 		piv = mas_safe_pivot(mas, pivots, i, type);
 
-		if (!piv && (i != 0))
-			break;
-
-		if (!mte_is_leaf(mas->node)) {
-			void *entry = mas_slot(mas, slots, i);
-
-			if (!entry)
-				pr_err("%p[%u] cannot be null\n",
-				       mas_mn(mas), i);
-
-			MT_BUG_ON(mas->tree, !entry);
+		if (!piv && (i != 0)) {
+			pr_err("Missing node limit pivot at %p[%u]",
+			       mas_mn(mas), i);
+			MAS_WARN_ON(mas, 1);
 		}
 
 		if (prev_piv > piv) {
@@ -7198,6 +7189,13 @@ static void mas_validate_limits(struct ma_state *mas)
 		if (piv == mas->max)
 			break;
 	}
+
+	if (mas_data_end(mas) != i) {
+		pr_err("node%p: data_end %u != the last slot offset %u\n",
+		       mas_mn(mas), mas_data_end(mas), i);
+		MT_BUG_ON(mas->tree, 1);
+	}
+
 	for (i += 1; i < mt_slots[type]; i++) {
 		void *entry = mas_slot(mas, slots, i);
 
-- 
2.20.1