On Fri, 2 Jul 2021 at 21:05, Mauro Carvalho Chehab <mchehab+huawei@xxxxxxxxxx> wrote: [System hanging after DVB receivers fail] > This is a very weird behavior. Never saw anything like that happening > with an upstream Kernel. Are you using anything else like some > proprietary driver or dvbloopback? > > Are there any messages printed by the Kernel when the machine starts > to die? > > If you're not using dvbloopback or a proprietary driver, I would > suspect that your PC hardware could have some issue... perhaps it > is overheating or there are some power issues on it, as it doesn't > make much sense that a fail to tune would cause a system hang. It's an ARch Linux system, and everything is vanilla. I get the impression the hanging is caused by blocking I/O on the device descriptors, but at least on the last time I happened it hung on shutdown after I had stopped all programs using the devices. So one of the modules could have been still holding the bad descriptor open, but I got the impression more than 90 seconds had passed before I pulled the plug, so systemd should have killed it by then, if that was what was blocking the shutdown. Another symptom I've seen is that it can cause tvheadend to busy loop with 100% on one CPU core, and become extremely slow to respond on its web server and to shut down, so overheating is a remote possibility. But as it's only affecting one core out of four, it's unlikely. Perhaps too much power is being drawn from the USB subsytem, but I would have thought Intel would have made sure their NUC PSUs are good quality. Years ago I saw something similar with a cheap Chinese IR receiver for a Windows Media remote control, it would make the system hang when plugged in. That may have been so long ago that it was kernel 2.x, let alone 3.x. Next time I notice the problem starting I'll check the logs straight away, but the trouble with system hangs is that they tend to destroy their evidence. I'll also see if unplugging the troublesome device and re-inserting it without rebooting is enough to revive it, because that could provide a better idea of hardware vs driver issues. -- TH
