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

This value controls the soft lockup detector thread’s behavior when a soft lockup condition is detected as to whether or not to gather further debug information. If enabled, each cpu will be issued an NMI and instructed to capture stack trace.

This feature is only applicable for architectures which support NMI.

0: do nothing. This is the default behavior.

1: on detection capture more debug information.