From 5f7c59126498f25959f81bd533af441f14ad7888 Mon Sep 17 00:00:00 2001 From: "Liam R. Howlett" Date: Tue, 11 Apr 2023 11:10:50 -0400 Subject: [PATCH] maple_tree: detect dead nodes in mas_start() 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: Fixes: 54a611b60590 ("Maple Tree: add new data structure") Signed-off-by: Liam Howlett Signed-off-by: Greg Kroah-Hartman --- lib/maple_tree.c | 4 ++++ 1 file changed, 4 insertions(+) diff --git a/lib/maple_tree.c b/lib/maple_tree.c index 54484bd..6b451a4 100644 --- a/lib/maple_tree.c +++ b/lib/maple_tree.c @@ -1352,12 +1352,16 @@ static inline struct maple_enode *mas_start(struct ma_state *mas) 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; } -- 2.7.4