Whoopsie, looks like I sent the updated logs twice. Oh well.

I’ll test upstream next.

@d3mia7, maybe you could try 3.3 too? FWIW, I haven’t seen this since installing 3.3.0-030300rc4-generic a month ago now. If your system’s prone to freeze this way, testing 3.3 could provide further evidence as to whether the issue’s fixed upstream.

Alright, I think this is safe to rule as invalid because the cause is most likely hardware failure: Oneiric boot media now also fails to boot here despite being the one used to install this system initially. I even went so far back as installing Jaunty (didn’t have anything more recent at hand, before Oneiric) and it also segfaults when X should start (though the graphical installer did work). I’ll still do tests if @Joseph disagrees (and has new ideas to test), but for now I’ll just settle for using fbdev (which seems to not trigger the issue).

I went back in Precise kernels [1] all the way back to 3.0.0-12.20. There seem to be no easy answers: now even 3.0.0-12.20 crashes with -intel.

I think this either means that the hardware’s broken, or that the issue has been lurking in kernels all the way back to (at least) 3.0.0-12.20, and was only triggered by some early Precise updates (during the time window I described above). As I said, it (definitely) wasn’t there when I filed Bug #903831 on 2011-12-13 (because I couldn’t have gotten far enough to trigger that bug with this on the way).

I’ll attach shots of current results with the early Precise kernels below just in case there’s anything useful there.

I think I’ll try ruling out hardware failure with Oneiric, either with the live disc (if that uses -intel) or by reinstalling.

* [1] https://launchpad.net/ubuntu/precise/+source/linux/

V3.3-rc6 still crashes, irregardless of RC6 being enabled/disabled.

My summary’s crap because this is difficult to summarize, hopefully the explanation below makes it clearer. I have little understanding of kernel internals, so I’ll first just try and describe the symptom as it appears.

I’ve come across an issue on my Fujitsu Siemens Amilo M7400 laptop with wistron_btns that is triggered by certain kernels, and once triggered, seems to affect all subsequent attempts to reboot with -pae kernels until a non-pae kernel is booted. I initially reported this on Launchpad [1].

I can currently trigger the issue by (cold or re-) booting 3.2.0-14-pae (these are Ubuntu’s packaged kernels) or by booting (for example) 3.3.0-030300rc4-generic-pae in recovery mode (= ”ro recovery nomodeset”). The recovery boot seems to work normally, but the 3.2.0-14-pae boot already exhibits the failure: it seemingly freezes. (More about the exact nature of ”failure” below.)

Once I’ve triggered the issue, rebooting with any -pae kernel fails similar to how 3.2.0-14-pae behaves irregardless of preceding boots.

I can ”fix” this by booting a non-pae kernel (which never fails). After that subsequent reboots with -pae kernels (apart from 3.2.0-14-pae) no longer fail — not until I do any of the triggering actions again.

Now, the ”failure” looks like a freeze, but it’s actually just an extreme slowdown. With patience, I can actually have the boot finish and can inspect logs. Dmesg reveals that wistron_btns is repeating ”Unknown key code 10” over and over.

If I comment wistron_btns out of /etc/modules so that it isn’t loaded, the issue goes away, meaning I can no longer trigger it.

As I said, I have little understanding of kernel bugs, so what I say next may be completely off, but the way I’ve interpreted this is that the ”brokenness” is actually hidden in the hardware, in something controlled by wistron_btns. Booting 3.2.0-14-pae/recovery booting any -pay puts the controller(?) in a ”broken” state from which a -pae kernel can’t recover, but a non-pae kernel can. And although -pae kernels later than 3.2.0-14 can’t recover a ”broken” controller, they also cannot put it into that ”broken” state (which is a good turn of development).

I’ll be happy to provide more info as requested. I’m attaching dmesg output for
starters.

* [1] https://bugs.launchpad.net/ubuntu/+source/linux/+bug/926012

With persistent booting I was able to get a panic [1] showing with 3.3.0-030300rc4, and it looks the same as what the dmesg I posted in #29 [2] showed: print_bad_pte+0x187/0x1e0 is on top the Trace. Despite the numerous boots I was still unable to reproduce the initial printk+0x2d/0x2f, so it may be fixed in Main or masked by the print_bad_pte+0x187/0x1e0 (though this still is based only on two datapoints in a frustratingly random issue).

Whether RC6 is enabled or disabled doesn’t seem to have bearing on this. 3.2.0-17 produces printk+0x2d/0x2f either way [3], and 3.2.0-18.28 also panics, though less consistently: I was only able to produce a sure printk+0x2d/0x2f once [4], with 3.2.0-18.28 non-pae. Mostly the errors fail to reveal themselves, and when they do, they are different from printk+0x2d/0x2f but also from each other: a couple of times a warn_slowpath_common+0x72/0xa0 (as in Bug #917668, though the hardware and pointers are different) occurred [5], and once it was a Bad page map [6] in unity-greeter.

* [1] https://bugs.launchpad.net/ubuntu/+source/linux/+bug/926007/comments/32
* [2] https://bugs.launchpad.net/ubuntu/+source/linux/+bug/926007/comments/29
* [3] https://bugs.launchpad.net/ubuntu/+source/linux/+bug/926007/comments/33
* [4] https://bugs.launchpad.net/ubuntu/+source/linux/+bug/926007/comments/34
* [5] https://bugs.launchpad.net/ubuntu/+source/linux/+bug/926007/comments/35
* [6] https://bugs.launchpad.net/ubuntu/+source/linux/+bug/926007/comments/36

I’ll upload a bunch of new screenshots for reference. They’re all related to testing this so bear with me, I’ll explain them further after uploading.

Still present in upstream 3.3.0-030300rc4 as it was in 3.2.0-17.27.

I tested 3.3.0-030300rc4 and couldn’t verify that the panic that all the 3.2’s above have is still present. Unfortunately I couldn’t prove it doesn’t either: with -intel, the first boot resulted in the ’low graphics mode’ failsafe dialog with Traces in dmesg (I’m attaching it). All subsequent boots resulted in panics that didn’t reveal a Trace, so they may or may not have been the one at hand. The panics still occurred when LDM should’ve launched, visually it either just showed the last lines of boot log or that with the mouse cursor. (The what’s-that-key was also blinking on the keyboard.)