[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] [Xen-devel] xend crash/hang scenario
I inadvertently found a way to crash/hang xend and almost completely lock oneself out of a domain. I was testing a new domain, and without thinking I did 'cat /dev/urandom' (rather than head or tail, oopsie) to make sure it was functioning. The resulting flood of output pegged xend at 99% cpu, where it stayed for 10 minutes before I killed it off. The real issue came after a restart, when I attempted to console back into the running domain. Either I had not managed to ctrl+c the `cat` prior to hanging xend or the output buffer was so full that it continued to spew garbage at me when I would restart xend and console in (I'm guessing). I got back on the the console a minute or so later by either managing to ctrl+c at the right time, or the output buffer finally emptied. This specific situation is not so scary since only people who didn't sleep enough *cough* would be cat-ing /dev/urandom, but I found that the event is not limited to something that silly. It seems that any large output of binary to the console will hang xend. I can reproduce the exact situation with "cat /usr/bin/vim" or any other decent-sized binary. Xend managed to recover from cat-ing binaries up to about 1.5mb, but anything larger than 2mb had xend using 99% cpu anywhere from 5 minutes to indefinitely (longer than I could wait anyway). Memory usage during the hangs does not go up appreciably. Strategic ctrl+c gets me back to console with relative ease, but it still requires a xend restart (sometimes 2 or 3) before I can get back in. In contrast to the binary output, even extremely large text files (500mb+) appear to have no ill effect, even when cat'd in a while loop. I have not tried outside of my setup so I don't know if it's reproducable, but it is very concerning to me that any user in any domain could, with a typo, crush the CPU and take out all management capability as well. I'll provide any additional info if it will help. Running Xen 2.0.3 Hardware: Dual Athlon XP 1900+ (1.6g) 512mb RAM Domain0: Gentoo 2004.3 running 2.6.10-xen0 128mb RAM allocated CPU0 DomainU: Gentoo 2004.3 2.6.10-xenU / default config / 128mb RAM allocated CPU1 -- +--------------------------------+ Mike Culbertson Senior Systems Administrator DiD : 646-230-8752/(M)646-382-4779 Mail: mike@xxxxxxxxxxxx +--------------------------------+ ------------------------------------------------------- This SF.Net email is sponsored by: IntelliVIEW -- Interactive Reporting Tool for open source databases. Create drag-&-drop reports. Save time by over 75%! Publish reports on the web. Export to DOC, XLS, RTF, etc. Download a FREE copy at http://www.intelliview.com/go/osdn_nl _______________________________________________ Xen-devel mailing list Xen-devel@xxxxxxxxxxxxxxxxxxxxx https://lists.sourceforge.net/lists/listinfo/xen-devel
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