From 3c769fd88b9742954763a968e84de09f7ad78cfe Mon Sep 17 00:00:00 2001 From: Peng Zhang Date: Tue, 11 Jul 2023 11:54:37 +0800 Subject: [PATCH] maple_tree: set the node limit when creating a new root node Set the node limit of the root node so that the last pivot of all nodes is the node limit (if the node is not full). This patch also fixes a bug in mas_rev_awalk(). Effectively, always setting a maximum makes mas_logical_pivot() behave as mas_safe_pivot(). Without this fix, it is possible that very small tasks would fail to find the correct gap. Although this has not been observed with real tasks, it has been reported to happen in m68k nommu running the maple tree tests. Link: https://lkml.kernel.org/r/20230711035444.526-1-zhangpeng.00@bytedance.com Link: https://lore.kernel.org/linux-mm/CAMuHMdV4T53fOw7VPoBgPR7fP6RYqf=CBhD_y_vOg53zZX_DnA@mail.gmail.com/ Link: https://lkml.kernel.org/r/20230711035444.526-2-zhangpeng.00@bytedance.com Fixes: 54a611b60590 ("Maple Tree: add new data structure") Signed-off-by: Peng Zhang Reviewed-by: Liam R. Howlett Tested-by: Geert Uytterhoeven Cc: Signed-off-by: Andrew Morton --- lib/maple_tree.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) diff --git a/lib/maple_tree.c b/lib/maple_tree.c index bfffbb7..4dd73cf 100644 --- a/lib/maple_tree.c +++ b/lib/maple_tree.c @@ -3692,7 +3692,8 @@ static inline int mas_root_expand(struct ma_state *mas, void *entry) mas->offset = slot; pivots[slot] = mas->last; if (mas->last != ULONG_MAX) - slot++; + pivots[++slot] = ULONG_MAX; + mas->depth = 1; mas_set_height(mas); ma_set_meta(node, maple_leaf_64, 0, slot); -- 2.7.4