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I'm on Kubuntu 15.04 on a HP zBook 14. Every few days, my computer locks up completely - screen stays on, sound get stuck and plays the last few tenths of a second of what ever was playing over and over. The kernel doesn't respond to magic keys (alt+ctrl + prtsrc, r,e,i,s,u,b - this works at other times). The only way I can get out of it is to hard reset with the power button. If I do this, the sound stops after 1-2 seconds of holding down the button. If I let go, it starts again. If I hold it down for 5 seconds, the computer restarts.

The only real sign on rebooting, is that some files (open files, I guess?), have a new line at the end that consists of a bunch of non-printing characters that show up in vim like

@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@

The only reason I noticed this is that my .zsh_history usually gets corrupted, but I've seen this in other files too (e.g. a .git/log/HEAD file).

I've checked logs:

  • kernel.log - I can't see anything relevant in the time before the crash, but at the time, there's a line similar to the .zsh_history
  • syslog - also nothing, also with one of those lines
  • Xorg.*.log - can't see anything here, but I'm not sure what how to decode the log index...
  • demsg - ends with a lot of lines like [17590.906375] retire_capture_urb: 11 callbacks suppressed - no idea if that's relevant.
  • lastlog - consists of one very long line (25k chars) with the same characters as the .zsh_history as mentioned above.
  • faillog - as lastlog, but 35k characters.

I can't see any other relevant ones. If there's any more info I can provide, please let me know.

Has anyone ever seen a crash like this, and might be able to tell me where I could start looking for a fix?

  • 1. FYI, those ^@ are NUL bytes, \000. 2. do you have another machine on the local network that you can configure your syslogd to send kernel log entries to? that may help. – cas Nov 26 '15 at 1:15
  • @cas This is a laptop, I'm often moving around, but I could see if I could find a computer to set something like that up on... Is there a good tutorial for how to do it anywhere? – naught101 Nov 26 '15 at 1:18
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    here's how to do it if you're using rsyslog: rsyslog.com/sending-messages-to-a-remote-syslog-server - you probably want remote logging of kern.* rather than *.*. – cas Nov 26 '15 at 1:20
  • Thanks @cas. I will see if I can get that set up somewhere. – naught101 Nov 26 '15 at 2:07

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