Patch "maple_tree: add smp_rmb() to dead node detection" has been added to the 6.1-stable tree

[gregkh at linuxfoundation.org]

This is a note to let you know that I've just added the patch titled

    maple_tree: add smp_rmb() to dead node detection

to the 6.1-stable tree which can be found at:
    http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
     maple_tree-add-smp_rmb-to-dead-node-detection.patch
and it can be found in the queue-6.1 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <stable at vger.kernel.org> know about it.


>From stable-owner at vger.kernel.org Tue Apr 11 17:15:03 2023
From: "Liam R. Howlett" <Liam.Howlett at oracle.com>
Date: Tue, 11 Apr 2023 11:10:53 -0400
Subject: maple_tree: add smp_rmb() to dead node detection
To: Greg Kroah-Hartman <gregkh at linuxfoundation.org>, stable at vger.kernel.org
Cc: maple-tree at lists.infradead.org, linux-mm at kvack.org, linux-kernel at vger.kernel.org, "Liam R. Howlett" <Liam.Howlett at Oracle.com>, "Liam R . Howlett" <Liam.Howlett at oracle.com>
Message-ID: <20230411151055.2910579-13-Liam.Howlett at oracle.com>

From: "Liam R. Howlett" <Liam.Howlett at Oracle.com>

commit 0a2b18d948838e16912b3b627b504ab062b7d02a upstream.

Add an smp_rmb() before reading the parent pointer to ensure that anything
read from the node prior to the parent pointer hasn't been reordered ahead
of this check.

The is necessary for RCU mode.

Link: https://lkml.kernel.org/r/20230227173632.3292573-7-surenb@google.com
Fixes: 54a611b60590 ("Maple Tree: add new data structure")
Cc: stable at vger.kernel.org
Signed-off-by: Liam R. Howlett <Liam.Howlett at oracle.com>
Signed-off-by: Greg Kroah-Hartman <gregkh at linuxfoundation.org>
---
 lib/maple_tree.c |    8 ++++++--
 1 file changed, 6 insertions(+), 2 deletions(-)

--- a/lib/maple_tree.c
+++ b/lib/maple_tree.c
@@ -529,9 +529,11 @@ static inline struct maple_node *mte_par
  */
 static inline bool ma_dead_node(const struct maple_node *node)
 {
-	struct maple_node *parent = (void *)((unsigned long)
-					     node->parent & ~MAPLE_NODE_MASK);
+	struct maple_node *parent;
 
+	/* Do not reorder reads from the node prior to the parent check */
+	smp_rmb();
+	parent = (void *)((unsigned long) node->parent & ~MAPLE_NODE_MASK);
 	return (parent == node);
 }
 
@@ -546,6 +548,8 @@ static inline bool mte_dead_node(const s
 	struct maple_node *parent, *node;
 
 	node = mte_to_node(enode);
+	/* Do not reorder reads from the node prior to the parent check */
+	smp_rmb();
 	parent = mte_parent(enode);
 	return (parent == node);
 }


Patches currently in stable-queue which might be from stable-owner at vger.kernel.org are

queue-6.1/maple_tree-fix-potential-rcu-issue.patch
queue-6.1/maple_tree-add-smp_rmb-to-dead-node-detection.patch
queue-6.1/maple_tree-add-rcu-lock-checking-to-rcu-callback-functions.patch
queue-6.1/maple_tree-fix-handle-of-invalidated-state-in-mas_wr_store_setup.patch
queue-6.1/maple_tree-reduce-user-error-potential.patch
queue-6.1/maple_tree-fix-mas_prev-and-mas_find-state-handling.patch
queue-6.1/maple_tree-remove-gfp_zero-from-kmem_cache_alloc-and-kmem_cache_alloc_bulk.patch
queue-6.1/maple_tree-be-more-cautious-about-dead-nodes.patch
queue-6.1/mm-enable-maple-tree-rcu-mode-by-default.patch
queue-6.1/maple_tree-detect-dead-nodes-in-mas_start.patch
queue-6.1/maple_tree-fix-freeing-of-nodes-in-rcu-mode.patch
queue-6.1/maple_tree-remove-extra-smp_wmb-from-mas_dead_leaves.patch
queue-6.1/maple_tree-refine-ma_state-init-from-mas_start.patch