Commit 6bdf0730 authored Jan 21, 2026 by Steven Rostedt Committed by Steven Rostedt (Google) Jan 26, 2026

tracing: Disable trace_printk buffer on warning too

When /proc/sys/kernel/traceoff_on_warning is set to 1, the top level
tracing buffer is disabled when a warning happens. This is very useful
when debugging and want the tracing buffer to stop taking new data when a
warning triggers keeping the events that lead up to the warning from being
overwritten.

Now that there is also a persistent ring buffer and an option to have
trace_printk go to that buffer, the same holds true for that buffer. A
warning could happen just before a crash but still write enough events to
lose the events that lead up to the first warning that was the reason for
the crash.

When /proc/sys/kernel/traceoff_on_warning is set to 1 and a warning is
triggered, not only disable the top level tracing buffer, but also disable
the buffer that trace_printk()s are written to.

Cc: Masami Hiramatsu <mhiramat@kernel.org>
Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Cc: Mark Rutland <mark.rutland@arm.com>
Link: https://patch.msgid.link/20260121093858.5c5d7e7b@gandalf.local.home


Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>

parent a9e0c589

kernel/trace/trace.c

+9 −0

Original line number	Diff line number	Diff line
		@@ -1666,9 +1666,18 @@ EXPORT_SYMBOL_GPL(tracing_off);
		void disable_trace_on_warning(void)
		{
		if (__disable_trace_on_warning) {
		struct trace_array *tr = READ_ONCE(printk_trace);

		trace_array_printk_buf(global_trace.array_buffer.buffer, _THIS_IP_,
		"Disabling tracing due to warning\n");
		tracing_off();

		/* Disable trace_printk() buffer too */
		if (tr != &global_trace) {
		trace_array_printk_buf(tr->array_buffer.buffer, _THIS_IP_,
		"Disabling tracing due to warning\n");
		tracer_tracing_off(tr);
		}
		}
		}