Judging only from the kernel messages you attached, there is no obvious crash seen indeed. The only point showing the line in 4.2: [ 152.197966] NMI watchdog: BUG: soft lockup - CPU#3 stuck for 22s! [swapper/3:0] that appears after a few warnings [ 125.714560] rtl8821ae:rtl8821ae_download_fw():<0-0> Firmware is not ready to run! So, something does actually block the kernel, but not in a form of the usual kernel Oops.