Patch "maple_tree: detect dead nodes in mas_start()" has been added to the 6.2-stable tree

[gregkh at linuxfoundation.org]

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

    maple_tree: detect dead nodes in mas_start()

to the 6.2-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-detect-dead-nodes-in-mas_start.patch
and it can be found in the queue-6.2 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 17:13:23 2023
From: "Liam R. Howlett" <Liam.Howlett at oracle.com>
Date: Tue, 11 Apr 2023 11:10:50 -0400
Subject: maple_tree: detect dead nodes in mas_start()
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>, Stable at vger.kernel.org, Liam Howlett <Liam.Howlett at oracle.com>
Message-ID: <20230411151055.2910579-10-Liam.Howlett at oracle.com>

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

commit a7b92d59c885018cb7bb88539892278e4fd64b29 upstream.

When initially starting a search, the root node may already be in the
process of being replaced in RCU mode.  Detect and restart the walk if
this is the case.  This is necessary for RCU mode of the maple tree.

Link: https://lkml.kernel.org/r/20230227173632.3292573-3-surenb@google.com
Cc: <Stable at vger.kernel.org>
Fixes: 54a611b60590 ("Maple Tree: add new data structure")
Signed-off-by: Liam Howlett <Liam.Howlett at oracle.com>
Signed-off-by: Greg Kroah-Hartman <gregkh at linuxfoundation.org>
---
 lib/maple_tree.c |    4 ++++
 1 file changed, 4 insertions(+)

--- a/lib/maple_tree.c
+++ b/lib/maple_tree.c
@@ -1357,12 +1357,16 @@ static inline struct maple_enode *mas_st
 		mas->max = ULONG_MAX;
 		mas->depth = 0;
 
+retry:
 		root = mas_root(mas);
 		/* Tree with nodes */
 		if (likely(xa_is_node(root))) {
 			mas->depth = 1;
 			mas->node = mte_safe_root(root);
 			mas->offset = 0;
+			if (mte_dead_node(mas->node))
+				goto retry;
+
 			return NULL;
 		}
 


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

queue-6.2/maple_tree-fix-potential-rcu-issue.patch
queue-6.2/maple_tree-add-smp_rmb-to-dead-node-detection.patch
queue-6.2/maple_tree-add-rcu-lock-checking-to-rcu-callback-functions.patch
queue-6.2/maple_tree-fix-handle-of-invalidated-state-in-mas_wr_store_setup.patch
queue-6.2/maple_tree-reduce-user-error-potential.patch
queue-6.2/maple_tree-fix-mas_prev-and-mas_find-state-handling.patch
queue-6.2/maple_tree-remove-gfp_zero-from-kmem_cache_alloc-and-kmem_cache_alloc_bulk.patch
queue-6.2/maple_tree-be-more-cautious-about-dead-nodes.patch
queue-6.2/mm-enable-maple-tree-rcu-mode-by-default.patch
queue-6.2/maple_tree-detect-dead-nodes-in-mas_start.patch
queue-6.2/maple_tree-fix-freeing-of-nodes-in-rcu-mode.patch
queue-6.2/maple_tree-remove-extra-smp_wmb-from-mas_dead_leaves.patch
queue-6.2/maple_tree-refine-ma_state-init-from-mas_start.patch