linux-kernel - [PATCH v4 4/5] tracing/kprobes: Make setup_boot_kprobe_events() asynchronous when trace_async

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Message-Id: <20260128125518.1715682-1-tianyaxiong@kylinos.cn>
Date: Wed, 28 Jan 2026 20:55:18 +0800
From: Yaxiong Tian <tianyaxiong@...inos.cn>
To: mhiramat@...nel.org,
	rostedt@...dmis.org,
	axboe@...nel.dk,
	mathieu.desnoyers@...icios.com,
	corbet@....net,
	skhan@...uxfoundation.org
Cc: linux-trace-kernel@...r.kernel.org,
	linux-block@...r.kernel.org,
	linux-kernel@...r.kernel.org,
	linux-doc@...r.kernel.org,
	Yaxiong Tian <tianyaxiong@...inos.cn>
Subject: [PATCH v4 4/5] tracing/kprobes: Make setup_boot_kprobe_events() asynchronous when trace_async_init set

During kernel boot, the setup_boot_kprobe_events() function causes
significant delays, increasing overall startup time.

The root cause is a lock contention chain: its child function
enable_boot_kprobe_events() requires the event_mutex, which is
already held by early_event_add_tracer(). early_event_add_tracer()
itself is blocked waiting for the trace_event_sem  read-write lock,
which is held for an extended period by trace_event_update_all().

To resolve this, when the trace_async_init parameter is enabled,
the execution of setup_boot_kprobe_events() is moved to the
trace_init_wq workqueue, allowing it to run asynchronously.

Signed-off-by: Yaxiong Tian <tianyaxiong@...inos.cn>
---
 kernel/trace/trace_kprobe.c | 14 +++++++++++++-
 1 file changed, 13 insertions(+), 1 deletion(-)

diff --git a/kernel/trace/trace_kprobe.c b/kernel/trace/trace_kprobe.c
index 89d2740f7bb5..fe69fc03018b 100644
--- a/kernel/trace/trace_kprobe.c
+++ b/kernel/trace/trace_kprobe.c
@@ -2031,6 +2031,13 @@ static __init int init_kprobe_trace_early(void)
 }
 core_initcall(init_kprobe_trace_early);
 
+static struct work_struct kprobe_trace_work __initdata;
+
+static void __init kprobe_trace_works_func(struct work_struct *work)
+{
+	setup_boot_kprobe_events();
+}
+
 /* Make a tracefs interface for controlling probe points */
 static __init int init_kprobe_trace(void)
 {
@@ -2052,7 +2059,12 @@ static __init int init_kprobe_trace(void)
 	if (kprobe_boot_events_buf[0] == '\0')
 		return 0;
 
-	setup_boot_kprobe_events();
+	if (trace_init_wq && trace_async_init) {
+		INIT_WORK(&kprobe_trace_work, kprobe_trace_works_func);
+		queue_work(trace_init_wq, &kprobe_trace_work);
+	} else {
+		setup_boot_kprobe_events();
+	}
 
 	return 0;
 }
-- 
2.25.1