FAILED: patch "[PATCH] bcache: Fix __bch_btree_node_alloc to make the failure" failed to apply to 5.4-stable tree

The patch below does not apply to the 5.4-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 <[email protected]>.

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-5.4.y
git checkout FETCH_HEAD
git cherry-pick -x 80fca8a10b604afad6c14213fdfd816c4eda3ee4
# <resolve conflicts, build, test, etc.>
git commit -s
git send-email --to '<[email protected]>' --in-reply-to '2023071620-dangling-strike-bfaa@gregkh' --subject-prefix 'PATCH 5.4.y' HEAD^..

Possible dependencies:

80fca8a10b60 ("bcache: Fix __bch_btree_node_alloc to make the failure behavior consistent") 17e4aed8309f ("bcache: remove 'int n' from parameter list of bch_bucket_alloc_set()")

thanks,

greg k-h

------------------ original commit in Linus's tree ------------------

From 80fca8a10b604afad6c14213fdfd816c4eda3ee4 Mon Sep 17 00:00:00 2001
From: Zheng Wang <[email protected]>
Date: Thu, 15 Jun 2023 20:12:22 +0800
Subject: [PATCH] bcache: Fix __bch_btree_node_alloc to make the failure
behavior consistent

In some specific situations, the return value of __bch_btree_node_alloc may be NULL. This may lead to a potential NULL pointer dereference in caller function like a calling chain :
btree_split->bch_btree_node_alloc->__bch_btree_node_alloc.

Fix it by initializing the return value in __bch_btree_node_alloc.

index 7c21e54468bf..0ddf91204782 100644
@@ -1090,10 +1090,12 @@ struct btree *__bch_btree_node_alloc(struct cache_set *c, struct btree_op *op,
 				     struct btree *parent)
 {
 	BKEY_PADDED(key) k;
-	struct btree *b = ERR_PTR(-EAGAIN);
+	struct btree *b;
 
 	mutex_lock(&c->bucket_lock);
 retry:
+	/* return ERR_PTR(-EAGAIN) when it fails */
+	b = ERR_PTR(-EAGAIN);
 	if (__bch_bucket_alloc_set(c, RESERVE_BTREE, &k.key, wait))
 		goto err;