FAILED: patch "[PATCH] kprobes: Fix to protect kick_kprobe_optimizer() by" failed to apply to 4.4-stable tree

The patch below does not apply to the 4.4-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]>.

thanks,

greg k-h

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

From 1a0aa991a6274161c95a844c58cfb801d681eb59 Mon Sep 17 00:00:00 2001
From: Masami Hiramatsu <[email protected]>
Date: Tue, 12 May 2020 17:02:56 +0900
Subject: [PATCH] kprobes: Fix to protect kick_kprobe_optimizer() by
kprobe_mutex

In kprobe_optimizer() kick_kprobe_optimizer() is called without kprobe_mutex, but this can race with other caller which is protected by kprobe_mutex.

To fix that, expand kprobe_mutex protected area to protect kick_kprobe_optimizer() call.

index ceb0e273bd69..0e185763578b 100644
@@ -592,11 +592,12 @@ static void kprobe_optimizer(struct work_struct *work)
 	mutex_unlock(&module_mutex);
 	mutex_unlock(&text_mutex);
 	cpus_read_unlock();
-	mutex_unlock(&kprobe_mutex);
 
 	/* Step 5: Kick optimizer again if needed */
 	if (!list_empty(&optimizing_list) || !list_empty(&unoptimizing_list))
 		kick_kprobe_optimizer();
+
+	mutex_unlock(&kprobe_mutex);
 }
 
 /* Wait for completing optimization and unoptimization */