[Novalug] Bug: soft lockup.

John Holland jholland@vin-dit.org
Sun Jul 12 18:53:37 EDT 2015


Try booting into single user mode.

Or,see if you can get a rescue shell from the installation disc.

If you can do either of those, maybe look at messages or dmesg in /var/log for clues. Maybe install a newer or older kernel and choose that  at boot time.

Yes you can mount your /home in another system, you can do it as root using the mount command without making it permanent in fstab. Choose a location on the other system you don't need, or make a new location for it. Or else the gui may just find the disk and shoe it to you. Don't hot-remove.



On Jul 12, 2015, 6:25 PM, at 6:25 PM, Gary Knott via Novalug <novalug@firemountain.net> wrote:
>We have a KDE Linux system with 2 disks; /home is
>in /dev/sdb1  which is all of /dev/sdb  as an ext3 filesystem.
>/, swap, /boot is on /dev/sda
>
>All of a sudden  (and after an update of a few packages
>that I paid no attention to) we can no longer
>use this system:  we get "Bug:  soft lockup - CPU#1 stuck for 23s
>[modprobe]"  And there seems to be no way
>around this.   Googling tells us that modprobe is
>running on CPU1 and is not relinquishing it!
>
>When we stick in a knoppix disk, we do not have
>this problem.
>
>Someone said changing their power supply fixed this, but
>as Knoppix runs, I am skepical.
>
>I guess we will try to install a new Linux system on
>/dev/sda  and loose all configuations, alias's etc,
>and special installed programs. Alas.
>
>But my question is, can I take the /home drive, put it
>in an LXDE Lubuntu system and mount it
>- say as /odsk and read/write it?   i.e. is there
>any special stuff - disk label etc, I am going to
>have to know about it?
>
>sub-question 1:  I think I plug the old drive in, and then
>boot and login.  Then I edit /etc/fstab and add a line for this
>disk,  copying how the other disk was specified, giving the
>"mount-point" /odsk. Then I do [cd / and mkdir odsk],
>and then give the command [mount /odsk] - all as root of course,
>and I'm ready to read/write in /odsk/home/user/...
>Is that right?
>
>sub-question 2:  When I shutdown and
>then reboot, will the added disk be there under /odsk
>and ready?
>
>sub-question number 3: If I pull the added disk back out,
>and reboot with a /etc/fstab entry for it, what will
>happen?   My guess is Linux will hang for awhile
>looking for this device and then give-up and keep
>booting, ignoring that fstab entry.  Is that right?
>
>sub-sub-question 3.1  If I remove the added disk
>while running  ( a "hot" unplug,) what will happen?
>Will the OS pay no attention as long as I never
>mention /odsk?  (Of course I'm not going to do this, I
>just want to know how Linux handles it.)
>
>subquestion 4:  Can I now put the disk back in
>and boot and find the disk under /odsk as before?
>
>penultimate question: I think modprobe is used
>to locate a "device driver" module and load it into
>kernel space.  how can I find out what device
>modprobe is hanging for?  (modem, speakers, CD-drive, etc?
>This is an old machine, circa 2003?.)
>If it is some non-essential device, I could just remove it, and
>see if I can boot.  But more to the point what's the
>cause of the failure?
>
>final question:  Does anybody know what else
>I could do about this kernel bug?  (There are some short
>googlable writeups explaining that this is really a kluge
>in linux with a special process devoted to checking
>for other processes that don't relinquish a cpu in a timely manner.
>
>Is there any reason to think the power supply or a capacitor
>could be the cause?
>
>Thanks,   gary knott, knott@civilized.com
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