maple_tree: detect dead nodes in mas_start()
commita7b92d59c8
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: <Stable@vger.kernel.org> Fixes:54a611b605
("Maple Tree: add new data structure") Signed-off-by: Liam Howlett <Liam.Howlett@oracle.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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@ -1352,12 +1352,16 @@ static inline struct maple_enode *mas_start(struct ma_state *mas)
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mas->max = ULONG_MAX;
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mas->depth = 0;
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retry:
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root = mas_root(mas);
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/* Tree with nodes */
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if (likely(xa_is_node(root))) {
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mas->depth = 1;
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mas->node = mte_safe_root(root);
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mas->offset = 0;
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if (mte_dead_node(mas->node))
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goto retry;
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return NULL;
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}
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