watchdog: Respect watchdog cpumask on CPU hotplug

KAGA-KOKO · KAGA-KOKO · commit 7dd476171149 · 2019-03-28T13:32:01.000+01:00
The rework of the watchdog core to use cpu_stop_work broke the watchdog cpumask on CPU hotplug. The watchdog_enable/disable() functions are now called unconditionally from the hotplug callback, i.e. even on CPUs which are not in the watchdog cpumask. As a consequence the watchdog can become unstoppable. Only invoke them when the plugged CPU is in the watchdog cpumask. Fixes: 9cf5773 ("watchdog/softlockup: Replace "watchdog/%u" threads with cpu_stop_work") Reported-by: Maxime Coquelin <maxime.coquelin@redhat.com> Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Tested-by: Maxime Coquelin <maxime.coquelin@redhat.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Oleg Nesterov <oleg@redhat.com> Cc: Michael Ellerman <mpe@ellerman.id.au> Cc: Nicholas Piggin <npiggin@gmail.com> Cc: Don Zickus <dzickus@redhat.com> Cc: Ricardo Neri <ricardo.neri-calderon@linux.intel.com> Cc: stable@vger.kernel.org Link: https://lkml.kernel.org/r/alpine.DEB.2.21.1903262245490.1789@nanos.tec.linutronix.de
diff --git a/kernel/watchdog.c b/kernel/watchdog.c
@@ -554,13 +554,15 @@ static void softlockup_start_all(void)
 
 int lockup_detector_online_cpu(unsigned int cpu)
 {
-	watchdog_enable(cpu);
+	if (cpumask_test_cpu(cpu, &watchdog_allowed_mask))
+		watchdog_enable(cpu);
 	return 0;
 }
 
 int lockup_detector_offline_cpu(unsigned int cpu)
 {
-	watchdog_disable(cpu);
+	if (cpumask_test_cpu(cpu, &watchdog_allowed_mask))
+		watchdog_disable(cpu);
 	return 0;
 }
 

Original file line number	Diff line number	Diff line change
`@@ -554,13 +554,15 @@ static void softlockup_start_all(void)`
`554`	`554`
`555`	`555`	`int lockup_detector_online_cpu(unsigned int cpu)`
`556`	`556`	`{`
`557`		`- watchdog_enable(cpu);`
	`557`	`+ if (cpumask_test_cpu(cpu, &watchdog_allowed_mask))`
	`558`	`+ watchdog_enable(cpu);`
`558`	`559`	`return 0;`
`559`	`560`	`}`
`560`	`561`
`561`	`562`	`int lockup_detector_offline_cpu(unsigned int cpu)`
`562`	`563`	`{`
`563`		`- watchdog_disable(cpu);`
	`564`	`+ if (cpumask_test_cpu(cpu, &watchdog_allowed_mask))`
	`565`	`+ watchdog_disable(cpu);`
`564`	`566`	`return 0;`
`565`	`567`	`}`
`566`	`568`