file: /proc/sys/kernel/hardlockup_all_cpu_backtrace
variable: kernel.hardlockup_all_cpu_backtrace
Official reference

This value controls the hard lockup detector behavior when a hard lockup condition is detected as to whether or not to gather further debug information. If enabled, arch-specific all-CPU stack dumping will be initiated.

0: do nothing. This is the default behavior.

1: on detection capture more debug information.