| From | Greg Kroah-Hartman <> | Subject | [PATCH 5.0 139/146] watchdog: Respect watchdog cpumask on CPU hotplug | Date | Mon, 1 Apr 2019 19:02:31 +0200 |
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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.linutronix.de 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; }
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