Comment 12 for bug 226397

I am having a similar fan problem since I upgraded to Intrepid -- didn't happen in previous versions of Ubuntu, which I use since 7.04. In my case it doesn't happen all that often --about 5 times in 5 weeks of using Intrepid-- but it is a problem nonetheless. There seems to be no particular circumstance triggering the fan behaviour, and it can start happening hours after having turned the computer on.

What I noticed in dmesg is the following:

Normal fan
==========
The "CPUx attaching sched-domain" message occurs shortly after starting the desktop session:
...
[ 70.571768] CPU0 attaching NULL sched-domain.
[ 70.571785] CPU1 attaching NULL sched-domain.
[ 70.574586] CPU0 attaching sched-domain:
[ 70.574597] domain 0: span 0-1 level MC
[ 70.574602] groups: 0 1
[ 70.574613] CPU1 attaching sched-domain:
[ 70.574617] domain 0: span 0-1 level MC
[ 70.574622] groups: 1 0
...

Fan goes bad
============
The "CPUx attaching sched-domain" message does not occur at the start of the desktop session. However, later I get:
...
[ 2034.964654] CPU0 attaching NULL sched-domain.
[ 2034.964673] CPU1 attaching NULL sched-domain.
[ 2034.972117] CPU0 attaching sched-domain:
[ 2034.972129] domain 0: span 0-1 level MC
[ 2034.972134] groups: 0 1
[ 2034.972146] CPU1 attaching sched-domain:
[ 2034.972150] domain 0: span 0-1 level MC
[ 2034.972154] groups: 1 0
[ 2037.704837] wlan0: authenticate with AP 00:1b:2f:50:cf:94
[more wlan authentication messages]
[ 2399.907705] wlan0: associated
[ 2402.525669] padlock: VIA PadLock not detected.

And later on:

[ 3157.907395] CE: hpet increasing min_delta_ns to 15000 nsec
[ 8011.064170] usb 4-1: USB disconnect, address 3
[ 8016.725661] CPU0 attaching NULL sched-domain.
[ 8016.725676] CPU1 attaching NULL sched-domain.
[ 8016.727606] CPU0 attaching sched-domain:
[ 8016.727616] domain 0: span 0-1 level MC
[ 8016.727621] groups: 0 1
[ 8016.727632] domain 1: span 0-1 level CPU
[ 8016.727637] groups: 0-1
[ 8016.727645] CPU1 attaching sched-domain:
[ 8016.727650] domain 0: span 0-1 level MC
[ 8016.727654] groups: 1 0
[ 8016.727675] domain 1: span 0-1 level CPU
[ 8016.727680] groups: 0-1
[ 8054.188887] CPU0 attaching NULL sched-domain.
[ 8054.188905] CPU1 attaching NULL sched-domain.
[ 8054.193246] CPU0 attaching sched-domain:
[ 8054.193257] domain 0: span 0-1 level MC
[ 8054.193263] groups: 0 1
[ 8054.193273] CPU1 attaching sched-domain:
[ 8054.193277] domain 0: span 0-1 level MC
[ 8054.193282] groups: 1 0
[end]

I don't know how the wlan or usb events above relate to the sched-domain messages (other than coinciding in time within a margin of a few seconds in an otherwise clean dmesg). I don't know when the fan went wrong, since it wasn't I who was using the computer and only noticed it later (22000 seconds after boot), but my bet is that it was at either 2000 or 8000 seconds.

Perhaps the above logs may be meaningful to someone else?

BTW, my laptop is similar to eldragon's. Also, I'm using the unmodified 2.6.27-8.17 kernel which was in the intrepid-proposed repository (haven't upgraded because of bug #294667). 2.6.27-7 behaved the same.