From: "Liam R. Howlett" <Liam.Howlett@xxxxxxxxxx> 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@xxxxxxxxxx Cc: <Stable@xxxxxxxxxxxxxxx> Fixes: 54a611b60590 ("Maple Tree: add new data structure") Signed-off-by: Liam Howlett <Liam.Howlett@xxxxxxxxxx> Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> --- lib/maple_tree.c | 4 ++++ 1 file changed, 4 insertions(+) --- a/lib/maple_tree.c +++ b/lib/maple_tree.c @@ -1352,12 +1352,16 @@ 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; }
