5.0-stable review patch. If anyone has any objections, please let me know.
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From: Thomas Gleixner tglx@linutronix.de
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 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.linut... Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org
--- 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; }