My computer has a problem where occasionally it will become completely unresponsive. (Mouse cursor doesn’t move. Keys have no apparently effect. Whatever app is running freezes. I think its a hardware problem with the graphics card, but I don’t know what. Logs at the time it freezes say “the GPU has fallen off the bus”.)
Anyway… I recently learnt about Magic SysRq. And I’ve been able to shutdown the computer from this unresponsive state with SysRq, R E I S U O. Where as I understand it, the “E” tells processes the end nicely if they can; and then the “I” just ends them by force.
(At this point, I’m realising that the E is SIGTERM, not SIGINT - so that screws up the relevance of my story; but I figure I’ll keep going anyway.)
The point is, I’ve been using key combo with a nice pause between each key, thinking there was some chance that processes might be ending gracefully. But when I tried it while the computer wasn’t frozen, the computer was able to inform me that the E and I commands were disabled. (I don’t know why.) So even though I wanted to give a nice “please end” signal, in the end that just wasn’t happening.
I’m not sure what you mean. Stop my computer from hanging like that? Or make it so that SIGTERM and SIGKILL work with those magic keys? I don’t know what an OOM killer is.
I’d definitely be interested in something that stopped the computer from crashing. But I kind of doubt that’s going to happen; because as I said, I’m pretty sure it’s a hardware thing. (But I suppose appropriate software might allow it to successful recover from the problem without having to restart.) It’s pretty rare by the way. I use the computer almost every day, and I haven’t had this problem happen for a few weeks. I’ve basically given up trying to fix it.
Yeah the hanging is being caused by your RAM being filled. Systemd-oomd will kill things more aggressively than the kernel out-of-memory handler that should stop it from locking up.
Alright, then that sounds like its definitely worth trying. Thanks for the suggestion. I guess it will be hard for me to tell whether or not it is working, because in the ideal case: nothing happens. But I’ll definitely try it out and hope for the best.
Have you tried other TTYs? When I press Ctrl+Alt+F3, for example, I switch to a ‘real’ terminal that (I assume) doesn’t require the GPU to work. From there you might be able to recover.
On Linux Mint the default, graphical userface is on TTY7 (CTRL+Alt+F7).
Yes, I have tried that. But it has no apparent effect when the computer is in that frozen state. (i.e. pressing ctrl+alt+F3 or whatever doesn’t change what is on the screen.
One time I tried imagining that the terminal came up, and so I ‘signed in’ and tried to shut down without seeing anything on the screen. But it didn’t work. … but since I couldn’t see anything, it’s quite possible I just mistyped something. So I guess that’s inconclusive.
My computer has a problem where occasionally it will become completely unresponsive. (Mouse cursor doesn’t move. Keys have no apparently effect. Whatever app is running freezes. I think its a hardware problem with the graphics card, but I don’t know what. Logs at the time it freezes say “the GPU has fallen off the bus”.)
Anyway… I recently learnt about Magic SysRq. And I’ve been able to shutdown the computer from this unresponsive state with
SysRq, R E I S U O. Where as I understand it, the “E” tells processes the end nicely if they can; and then the “I” just ends them by force.(At this point, I’m realising that the
Eis SIGTERM, not SIGINT - so that screws up the relevance of my story; but I figure I’ll keep going anyway.)The point is, I’ve been using key combo with a nice pause between each key, thinking there was some chance that processes might be ending gracefully. But when I tried it while the computer wasn’t frozen, the computer was able to inform me that the E and I commands were disabled. (I don’t know why.) So even though I wanted to give a nice “please end” signal, in the end that just wasn’t happening.
You could try enabling systemd-oomd. It’s a userspace OOM killer and seems to be aggressive enough to mostly stop that from happening.
I’m not sure what you mean. Stop my computer from hanging like that? Or make it so that SIGTERM and SIGKILL work with those magic keys? I don’t know what an OOM killer is.
I’d definitely be interested in something that stopped the computer from crashing. But I kind of doubt that’s going to happen; because as I said, I’m pretty sure it’s a hardware thing. (But I suppose appropriate software might allow it to successful recover from the problem without having to restart.) It’s pretty rare by the way. I use the computer almost every day, and I haven’t had this problem happen for a few weeks. I’ve basically given up trying to fix it.
Yeah the hanging is being caused by your RAM being filled. Systemd-oomd will kill things more aggressively than the kernel out-of-memory handler that should stop it from locking up.
Alright, then that sounds like its definitely worth trying. Thanks for the suggestion. I guess it will be hard for me to tell whether or not it is working, because in the ideal case: nothing happens. But I’ll definitely try it out and hope for the best.
Have you tried other TTYs? When I press Ctrl+Alt+F3, for example, I switch to a ‘real’ terminal that (I assume) doesn’t require the GPU to work. From there you might be able to recover.
On Linux Mint the default, graphical userface is on TTY7 (CTRL+Alt+F7).
Yes, I have tried that. But it has no apparent effect when the computer is in that frozen state. (i.e. pressing ctrl+alt+F3 or whatever doesn’t change what is on the screen.
One time I tried imagining that the terminal came up, and so I ‘signed in’ and tried to shut down without seeing anything on the screen. But it didn’t work. … but since I couldn’t see anything, it’s quite possible I just mistyped something. So I guess that’s inconclusive.