The patch titled
Subject: maple_tree: detect dead nodes in mas_start()
has been added to the -mm mm-unstable branch. Its filename is
maple_tree-detect-dead-nodes-in-mas_start.patch
This patch will shortly appear at
https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/maple_tree-detect-dead-nodes-in-mas_start.patch
This patch will later appear in the mm-unstable branch at
git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm
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------------------------------------------------------
From: Liam Howlett <Liam.Howlett@xxxxxxxxxx>
Subject: maple_tree: detect dead nodes in mas_start()
Date: Mon, 27 Feb 2023 09:36:01 -0800
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@xxxxxxxxxx
Fixes: 54a611b60590 ("Maple Tree: add new data structure")
Signed-off-by: Liam Howlett <Liam.Howlett@xxxxxxxxxx>
Signed-off-by: Suren Baghdasaryan <surenb@xxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
--- a/lib/maple_tree.c~maple_tree-detect-dead-nodes-in-mas_start
+++ a/lib/maple_tree.c
@@ -1360,12 +1360,16 @@ 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 -mm which might be from Liam.Howlett@xxxxxxxxxx are
mm-mprotect-fix-successful-vma_merge-of-next-in-do_mprotect_pkey.patch
maple_tree-be-more-cautious-about-dead-nodes.patch
maple_tree-detect-dead-nodes-in-mas_start.patch
maple_tree-fix-freeing-of-nodes-in-rcu-mode.patch
maple_tree-remove-extra-smp_wmb-from-mas_dead_leaves.patch
maple_tree-fix-write-memory-barrier-of-nodes-once-dead-for-rcu-mode.patch
maple_tree-add-smp_rmb-to-dead-node-detection.patch
maple_tree-add-rcu-lock-checking-to-rcu-callback-functions.patch
mm-enable-maple-tree-rcu-mode-by-default.patch
