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Message-ID: <20250731030125.3817484-1-senozhatsky@chromium.org>
Date: Thu, 31 Jul 2025 12:01:08 +0900
From: Sergey Senozhatsky <senozhatsky@...omium.org>
To: "Rafael J. Wysocki" <rafael@...nel.org>,
Pavel Machek <pavel@...nel.org>
Cc: Tomasz Figa <tfiga@...omium.org>,
linux-pm@...r.kernel.org,
linux-kernel@...r.kernel.org,
Sergey Senozhatsky <senozhatsky@...omium.org>
Subject: [PATCH] PM: dpm: add module param to backtrace all CPUs
Add dpm_all_cpu_backtrace module parameter which controls
all CPU backtrace dump before DPM panics the system. This
is expected to help understanding what might have caused
device timeout.
Signed-off-by: Sergey Senozhatsky <senozhatsky@...omium.org>
---
drivers/base/power/main.c | 8 ++++++++
1 file changed, 8 insertions(+)
diff --git a/drivers/base/power/main.c b/drivers/base/power/main.c
index dbf5456cd891..23abad9f039f 100644
--- a/drivers/base/power/main.c
+++ b/drivers/base/power/main.c
@@ -34,6 +34,7 @@
#include <linux/cpufreq.h>
#include <linux/devfreq.h>
#include <linux/timer.h>
+#include <linux/nmi.h>
#include "../base.h"
#include "power.h"
@@ -517,6 +518,9 @@ struct dpm_watchdog {
#define DECLARE_DPM_WATCHDOG_ON_STACK(wd) \
struct dpm_watchdog wd
+static bool __read_mostly dpm_all_cpu_backtrace;
+module_param(dpm_all_cpu_backtrace, bool, 0644);
+
/**
* dpm_watchdog_handler - Driver suspend / resume watchdog handler.
* @t: The timer that PM watchdog depends on.
@@ -532,8 +536,12 @@ static void dpm_watchdog_handler(struct timer_list *t)
unsigned int time_left;
if (wd->fatal) {
+ unsigned int this_cpu = smp_processor_id();
+
dev_emerg(wd->dev, "**** DPM device timeout ****\n");
show_stack(wd->tsk, NULL, KERN_EMERG);
+ if (dpm_all_cpu_backtrace)
+ trigger_allbutcpu_cpu_backtrace(this_cpu);
panic("%s %s: unrecoverable failure\n",
dev_driver_string(wd->dev), dev_name(wd->dev));
}
--
2.50.1.565.gc32cd1483b-goog
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