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