From 63242f1c6d84cdfe34cd94aa9345f964a3de1f36 Mon Sep 17 00:00:00 2001 From: Liam Howlett Date: Mon, 27 Feb 2023 09:36:01 -0800 Subject: [PATCH] maple_tree: detect dead nodes in mas_start() 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 --- lib/maple_tree.c | 4 ++++ 1 file changed, 4 insertions(+) diff --git a/lib/maple_tree.c b/lib/maple_tree.c index 194963149c2d2..6fcf08dbdbf96 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; } -- 2.50.1