On Tue, 2017-09-12 at 09:20 +1000, Morgan Reed wrote: > In all likelihood the process wasn't "hung" per-se, more likely > random > hadn't been seeded yet and as such you *can't* get 4096b of entropy > out of > it (so the process was attempting to do its job, just nothing on the > device). > > The issue is basically that there are very few "good" entropy sources > in a > VM environment, and as such (particularly on a machine which is only > running SSH) there's not enough data available to seed random. > > Check 'man 4 random' for some discussion. >
The save-entropy files get written from a crontab entry. That means the system is already up and running, which means it's well past the point of hanging because it needs to be seeded. Once it is seeded, it can never "run out of entropy". So all in all, this is a genuine problem of some sort. The fact that the save-entropy process has accumulated 48+ minutes of cpu time is another problem indicator. The process state is RL, runnable and waiting to acquire a lock, which seems contradictory (unless that means it's waiting for a spinlock maybe). -- Ian > On Tue, Sep 12, 2017 at 12:02 AM, Vick Khera <vi...@khera.org> wrote: > > > > > I just had a VM running in Google's cloud become totally useless, > > and I > > tracked it down to the save-entropy operation. > > > > Basically this process was sucking up all CPU, even when nothing > > else > > running other than my ssh shell: > > > > % ps axuw803 > > USER PID %CPU %MEM VSZ RSS TT STAT STARTED TIME COMMAND > > operator 803 100.0 0.1 8336 2096 - RL 08:55 48:20.14 dd > > if=/dev/random of=saved-entropy.1 bs=4096 count=1 > > > > > > The process is unkillable, and I cannot even get the system to shut > > down. > > That has been hanging for about 10 minutes so far, with the last > > output > > being > > > > System shutdown time has arrive90 second watchdSep 11 09:50:02 > > yertle init: > > /bin/sh on /etc/rc.shutdown terminated abnormally, going to single > > user > > mode > > Sep 11 09:50:47 init: some processes would not die; ps axl advised > > Waiting (max 60 seconds) for system process `vnlru' to stop... done > > Waiting (max 60 seconds) for system process `bufdaemon' to stop... > > done > > Waiting (max 60 seconds) for system process `syncer' to stop... > > Syncing disks, vnodes remaining... 4 4 4 4 4 4 4 timed out > > 2 2 2 2 2 2 2 > > > > > > Running FreeBSD 11.1-p1 on a 1CPU standard machine in GCE. > > > > What's the proper recovery from this kind of lockup, or how to > > prevent it? > > I've never encountered this on a bare metal system, or other KVM > > based > > machines. > > _______________________________________________ > > freebsd-stable@freebsd.org mailing list > > https://lists.freebsd.org/mailman/listinfo/freebsd-stable > > To unsubscribe, send any mail to "freebsd-stable-unsubscribe@freebs > > d.org" > > > > _______________________________________________ freebsd-stable@freebsd.org mailing list https://lists.freebsd.org/mailman/listinfo/freebsd-stable To unsubscribe, send any mail to "freebsd-stable-unsubscr...@freebsd.org"
