Starting with the first 4.18 RC kernel, my system experiences general protection faults leading to kernel panic shortly after the login prompt appears on most boots. Occasionally that doesn't happen and instead numerous other seemingly random stack traces are printed (bad page map, scheduling while atomic, null pointer deref, etc), but either way the system is unusable. This bug remains up through the latest mainline kernel 4.19-rc2.
Booting with my USB ATSC tv tuner disconnected prevents the bug from happening.
Kernel bisection between v4.17 and 4.18-rc1 shows problem is caused by:
1a0c10ed7bb1 media: dvb-usb-v2: stop using coherent memory for URBs
Building both 4.18.6 and 4.19-rc2 with that commit reverted resolves the bug for me.
My DVB hardware uses driver mxl111sf:
Bus 002 Device 003: ID 2040:c61b Hauppauge
idVendor 0x2040 Hauppauge
iManufacturer 1 Hauppauge
iProduct 2 WinTV Aero-M
Other system info:
Arch Linux x86_64
16 GB ram
You could try to see if it fixes the issue for you.