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Message-Id: <20230327185532.2354250-4-Liam.Howlett@oracle.com>
Date: Mon, 27 Mar 2023 14:55:27 -0400
From: "Liam R. Howlett" <Liam.Howlett@...cle.com>
To: Linus Torvalds <torvalds@...ux-foundation.org>,
Andrew Morton <akpm@...ux-foundation.org>,
maple-tree@...ts.infradead.org, linux-mm@...ck.org,
linux-kernel@...r.kernel.org, Matthew Wilcox <willy@...radead.org>,
Suren Baghdasaryan <surenb@...gle.com>
Cc: "Liam R. Howlett" <Liam.Howlett@...cle.com>,
Stable@...r.kernel.org,
"Liam R . Howlett" <Liam.Howlett@...cle.com>
Subject: [PATCH 3/8] maple_tree: fix freeing of nodes in rcu mode
From: "Liam R. Howlett" <Liam.Howlett@...cle.com>
The walk to destroy the nodes was not always setting the node type and
would result in a destroy method potentially using the values as nodes.
Avoid this by setting the correct node types. This is necessary for the
RCU mode of the maple tree.
Link: https://lkml.kernel.org/r/20230227173632.3292573-4-surenb@google.com
Cc: <Stable@...r.kernel.org>
Fixes: 54a611b60590 ("Maple Tree: add new data structure")
Signed-off-by: Liam R. Howlett <Liam.Howlett@...cle.com>
---
lib/maple_tree.c | 73 ++++++++++++++++++++++++++++++++++++++++--------
1 file changed, 62 insertions(+), 11 deletions(-)
diff --git a/lib/maple_tree.c b/lib/maple_tree.c
index 089cd76ec379..44d6ce30b28e 100644
--- a/lib/maple_tree.c
+++ b/lib/maple_tree.c
@@ -902,6 +902,44 @@ static inline void ma_set_meta(struct maple_node *mn, enum maple_type mt,
meta->end = end;
}
+/*
+ * mas_clear_meta() - clear the metadata information of a node, if it exists
+ * @mas: The maple state
+ * @mn: The maple node
+ * @mt: The maple node type
+ * @offset: The offset of the highest sub-gap in this node.
+ * @end: The end of the data in this node.
+ */
+static inline void mas_clear_meta(struct ma_state *mas, struct maple_node *mn,
+ enum maple_type mt)
+{
+ struct maple_metadata *meta;
+ unsigned long *pivots;
+ void __rcu **slots;
+ void *next;
+
+ switch (mt) {
+ case maple_range_64:
+ pivots = mn->mr64.pivot;
+ if (unlikely(pivots[MAPLE_RANGE64_SLOTS - 2])) {
+ slots = mn->mr64.slot;
+ next = mas_slot_locked(mas, slots,
+ MAPLE_RANGE64_SLOTS - 1);
+ if (unlikely((mte_to_node(next) && mte_node_type(next))))
+ return; /* The last slot is a node, no metadata */
+ }
+ fallthrough;
+ case maple_arange_64:
+ meta = ma_meta(mn, mt);
+ break;
+ default:
+ return;
+ }
+
+ meta->gap = 0;
+ meta->end = 0;
+}
+
/*
* ma_meta_end() - Get the data end of a node from the metadata
* @mn: The maple node
@@ -5455,20 +5493,22 @@ static inline int mas_rev_alloc(struct ma_state *mas, unsigned long min,
* mas_dead_leaves() - Mark all leaves of a node as dead.
* @mas: The maple state
* @slots: Pointer to the slot array
+ * @type: The maple node type
*
* Must hold the write lock.
*
* Return: The number of leaves marked as dead.
*/
static inline
-unsigned char mas_dead_leaves(struct ma_state *mas, void __rcu **slots)
+unsigned char mas_dead_leaves(struct ma_state *mas, void __rcu **slots,
+ enum maple_type mt)
{
struct maple_node *node;
enum maple_type type;
void *entry;
int offset;
- for (offset = 0; offset < mt_slot_count(mas->node); offset++) {
+ for (offset = 0; offset < mt_slots[mt]; offset++) {
entry = mas_slot_locked(mas, slots, offset);
type = mte_node_type(entry);
node = mte_to_node(entry);
@@ -5487,14 +5527,13 @@ unsigned char mas_dead_leaves(struct ma_state *mas, void __rcu **slots)
static void __rcu **mas_dead_walk(struct ma_state *mas, unsigned char offset)
{
- struct maple_node *node, *next;
+ struct maple_node *next;
void __rcu **slots = NULL;
next = mas_mn(mas);
do {
- mas->node = ma_enode_ptr(next);
- node = mas_mn(mas);
- slots = ma_slots(node, node->type);
+ mas->node = mt_mk_node(next, next->type);
+ slots = ma_slots(next, next->type);
next = mas_slot_locked(mas, slots, offset);
offset = 0;
} while (!ma_is_leaf(next->type));
@@ -5558,11 +5597,14 @@ static inline void __rcu **mas_destroy_descend(struct ma_state *mas,
node = mas_mn(mas);
slots = ma_slots(node, mte_node_type(mas->node));
next = mas_slot_locked(mas, slots, 0);
- if ((mte_dead_node(next)))
+ if ((mte_dead_node(next))) {
+ mte_to_node(next)->type = mte_node_type(next);
next = mas_slot_locked(mas, slots, 1);
+ }
mte_set_node_dead(mas->node);
node->type = mte_node_type(mas->node);
+ mas_clear_meta(mas, node, node->type);
node->piv_parent = prev;
node->parent_slot = offset;
offset = 0;
@@ -5582,13 +5624,18 @@ static void mt_destroy_walk(struct maple_enode *enode, unsigned char ma_flags,
MA_STATE(mas, &mt, 0, 0);
- if (mte_is_leaf(enode))
+ mas.node = enode;
+ if (mte_is_leaf(enode)) {
+ node->type = mte_node_type(enode);
goto free_leaf;
+ }
+ ma_flags &= ~MT_FLAGS_LOCK_MASK;
mt_init_flags(&mt, ma_flags);
mas_lock(&mas);
- mas.node = start = enode;
+ mte_to_node(enode)->ma_flags = ma_flags;
+ start = enode;
slots = mas_destroy_descend(&mas, start, 0);
node = mas_mn(&mas);
do {
@@ -5596,7 +5643,8 @@ static void mt_destroy_walk(struct maple_enode *enode, unsigned char ma_flags,
unsigned char offset;
struct maple_enode *parent, *tmp;
- node->slot_len = mas_dead_leaves(&mas, slots);
+ node->type = mte_node_type(mas.node);
+ node->slot_len = mas_dead_leaves(&mas, slots, node->type);
if (free)
mt_free_bulk(node->slot_len, slots);
offset = node->parent_slot + 1;
@@ -5620,7 +5668,8 @@ static void mt_destroy_walk(struct maple_enode *enode, unsigned char ma_flags,
} while (start != mas.node);
node = mas_mn(&mas);
- node->slot_len = mas_dead_leaves(&mas, slots);
+ node->type = mte_node_type(mas.node);
+ node->slot_len = mas_dead_leaves(&mas, slots, node->type);
if (free)
mt_free_bulk(node->slot_len, slots);
@@ -5630,6 +5679,8 @@ static void mt_destroy_walk(struct maple_enode *enode, unsigned char ma_flags,
free_leaf:
if (free)
mt_free_rcu(&node->rcu);
+ else
+ mas_clear_meta(&mas, node, node->type);
}
/*
--
2.39.2
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