From: "Liam R. Howlett" Liam.Howlett@Oracle.com

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@vger.kernel.org Fixes: 54a611b60590 ("Maple Tree: add new data structure") Signed-off-by: Liam R. Howlett Liam.Howlett@oracle.com --- lib/maple_tree.c | 4 ++++ 1 file changed, 4 insertions(+)

diff --git a/lib/maple_tree.c b/lib/maple_tree.c index cc356b8369ad..089cd76ec379 100644 --- a/lib/maple_tree.c +++ b/lib/maple_tree.c @@ -1360,12 +1360,16 @@ 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; }