Kernel 'bisection'

Chris cpollock at embarqmail.com
Sun Feb 15 01:23:30 UTC 2015


On Sat, 2015-02-14 at 15:40 -0800, Bob wrote:
> ** Reply to message from Chris <cpollock at embarqmail.com> on Sat, 14 Feb 2015
> 16:20:25 -0600
> 
> > On Sat, 2015-02-14 at 13:42 -0500, Scott Blair wrote:
> > > On 02/14/2015 08:19 AM, Chris wrote:
> > > > On Sat, 2015-02-14 at 13:05 +0000, Peter Waller wrote:
> > > >> Briefly, bisection is a way of taking a long list of 1000's of
> > > >> changes, and arranging things so that you only have to test more like
> > > >> 10 of them, because you test midpoints. (and 2^10 ~ 1000).
> > > >>
> > > >>
> > > >> More detail:
> > > >>
> > > >>
> > > >> http://alblue.bandlem.com/2011/07/git-tip-of-week-git-bisect.html
> > > >>
> > > >>
> > > >> On 14 February 2015 at 12:57, Liam Proven <lproven at gmail.com> wrote:
> > > >>          On 14 February 2015 at 02:59, Chris <cpollock at embarqmail.com>
> > > >>          wrote:
> > > >>          > Who can give me some pointers on doing a kernel bisection on
> > > >>          either
> > > >>          > 3.13.0-35 or -36 kernels? Ever since one of those two were
> > > >>          installed,
> > > >>          > I'm on -45 now, my system will lockup (black screen, cursor
> > > >>          moves, but
> > > >>          > CTRL-ALT-F1 will not take me to a terminal log-in. This is
> > > >>          the error I
> > > >>          > see - Feb 13 19:05:22 localhost kernel: [807775.808019]
> > > >>          > [drm:i915_hangcheck_elapsed] *ERROR* Hangcheck timer
> > > >>          elapsed... render
> > > >>          > ring idle. I've reported this last year on Launchpad as bug
> > > >>          -
> > > >>          > https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1402331
> > > >>          I've jumped
> > > >>          > through all the hoops that have been suggested there except
> > > >>          doing a
> > > >>          > kernel bisection which seems to have me confused. I'm really
> > > >>          getting a
> > > >>          > bit tired of these continued 'lockups'.
> > > >>          
> > > >>          
> > > >>          I have to ask. WTF is a "kernel bisection"?
> > > >>          
> > > >>          You want to... cut your kernel in half? Is this some kind of
> > > >>          Solomonic
> > > >>          judgement? Because, you know, like half a baby doesn't work,
> > > >>          half a
> > > >>          kernel won't, either.
> > > >>          
> > > > That, to me, is as clear as mud just as these instructions on doing it
> > > > are - https://wiki.ubuntu.com/Kernel/KernelBisection I can't live with
> > > > having these 'lockups' every 2-10 days, more or less and I say that
> > > > because it's so very random I have no idea what even triggers it.
> > > >
> > > >
> > > Chris, I just had a lock up about 3 minutes go. I saw that my memory sky 
> > > rocketed, physical 99% and swap 90%. Normally they run low. CPU was 
> > > running normal when it happened. I was logging into a flash page when it 
> > > happened. The flash page finally crashed and everything went back to 
> > > normal. I am using Ubuntu 14. 04 kernel 3.13.0-45-generic and Chrome 
> > > 40.0.2214.111 64 bit. Don't know if this will help in your problem.
> > > 
> > > -- 
> > > 
> > > Scott Blair
> > > 
> > > Save on back up time BackupDevice=Null
> > > 
> > > 
> > I've had flash crash a few times since the latest update. Did the system
> > 'lockup'?
> 
> I have had my computer lockup twice the past few weeks.  I was not using a
> browser the last time the lockup occurred and don't remember what I was doing
> the first time it locked up.
> 
> 
> > For instance I have my clock showing seconds when this happens
> > to me the screen locks up however all background operations such as
> > fetchmail, procmail, spamassassin and so forth continue to run.
> 
> These are the symptoms I also see.  There are no screen updates and the cursor
> moves but the system will not accept any other input and anything already
> running continues to run.
> 
> 
> > If you
> > didn't see that type of a lockup then it must have just been flash.
> > However you can check your syslog for kernel: [ 8248.820016]
> > [drm:i915_hangcheck_elapsed] *ERROR* Hangcheck timer elapsed... render
> > ring idle to see if you have the same issue.
> 
> The last time I had the system lockup I left it running over night to see if
> anything would happen.  After a reboot I looked in the logs and could not find
> anything that happened at the time the lockup  occurred.  Checking my syslog I
> can not find the string "hangcheck".
> 
> 
> > 
> > On another note I just tried to regress to the 3.13.0-35 kernel, system
> > would boot but had no cursor and login screen didn't look right. Could
> > not login so I removed it. 
> > 
> > So basically I'm back to where I was before just waiting for someone
> > from either of the two bug reports to tell me what to do next and
> > waiting for the next lockup.
> 
> -- 
> Robert Blair
> 
Bob, possibly you can go here -
https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1402331 or here -
https://bugs.freedesktop.org/show_bug.cgi?id=75394 and make a comment,
probably both places would be best even if you don't see the 'hangcheck'
error you're experiencing the lockup. .

Hmm, at 19:06:06 I experienced another 'lockup'. I was able to CTRL>ALT>F1 login
and sudo reboot. Below is all that shows up in my syslog:

Feb 14 19:04:53 localhost kernel: [10683.755797] systemd-hostnamed[9328]: Warning: nss-myhostname is not installed. Changing the local hostname might make it unresolveable. Please install nss-myhostname!
Feb 14 19:04:53 localhost dbus[382]: [system] Successfully activated service 'org.freedesktop.hostname1'
Feb 14 19:09:48 localhost kernel: [10978.591143] [drm:intel_crtc_cursor_set], cursor off

I'm totally out of ideas but this will get added as a comment to the two bugs.

-- 
Chris
KeyID 0xE372A7DA98E6705C
31.11°N 97.89°W (Elev. 1092 ft)
19:18:12 up 7 min, 1 user, load average: 1.98, 0.83, 0.37
Ubuntu 14.04.1 LTS, kernel 3.13.0-45-generic




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