4.19-stable review patch. If anyone has any objections, please let me know.
------------------ From: Thomas Gleixner <[email protected]> commit 7dd47617114921fdd8c095509e5e7b4373cc44a1 upstream. 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: 9cf57731b63e ("watchdog/softlockup: Replace "watchdog/%u" threads with cpu_stop_work") Reported-by: Maxime Coquelin <[email protected]> Signed-off-by: Thomas Gleixner <[email protected]> Tested-by: Maxime Coquelin <[email protected]> Cc: Peter Zijlstra <[email protected]> Cc: Oleg Nesterov <[email protected]> Cc: Michael Ellerman <[email protected]> Cc: Nicholas Piggin <[email protected]> Cc: Don Zickus <[email protected]> Cc: Ricardo Neri <[email protected]> Cc: [email protected] Link: https://lkml.kernel.org/r/[email protected] Signed-off-by: Greg Kroah-Hartman <[email protected]> --- kernel/watchdog.c | 6 ++++-- 1 file changed, 4 insertions(+), 2 deletions(-) --- a/kernel/watchdog.c +++ b/kernel/watchdog.c @@ -547,13 +547,15 @@ 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; }
