The patch below does not apply to the 6.2-stable tree. If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to <stable@xxxxxxxxxxxxxxx>. To reproduce the conflict and resubmit, you may use the following commands: git fetch https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/ linux-6.2.y git checkout FETCH_HEAD git cherry-pick -x a7b92d59c885018cb7bb88539892278e4fd64b29 # <resolve conflicts, build, test, etc.> git commit -s git send-email --to '<stable@xxxxxxxxxxxxxxx>' --in-reply-to '2023041103-washcloth-overplay-32db@gregkh' --subject-prefix 'PATCH 6.2.y' HEAD^.. Possible dependencies: a7b92d59c885 ("maple_tree: detect dead nodes in mas_start()") 46b345848261 ("maple_tree: refine ma_state init from mas_start()") thanks, greg k-h ------------------ original commit in Linus's tree ------------------ >From a7b92d59c885018cb7bb88539892278e4fd64b29 Mon Sep 17 00:00:00 2001 From: Liam Howlett <Liam.Howlett@xxxxxxxxxx> 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@xxxxxxxxxx Fixes: 54a611b60590 ("Maple Tree: add new data structure") Signed-off-by: Liam Howlett <Liam.Howlett@xxxxxxxxxx> Signed-off-by: Suren Baghdasaryan <surenb@xxxxxxxxxx> Cc: <stable@xxxxxxxxxxxxxxx> Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> diff --git a/lib/maple_tree.c b/lib/maple_tree.c index 095b9cb1f4f1..3d53339656e1 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; }
