Created attachment 22922 [details] lspci for hardware details. How bug was caused? I did run apt-get upgrade in background while starting up firefox and pidgin. Now there went something wrong in ext4. So I don't know exactly how to reproduce this. Reproducing? Only once just a few minutes ago. Version where this was seen? Vanilla kernel v2.6.31-rc7 just a commit before tagging rc8 with a via agp driver bug patch. User land is Ubuntu Karmic. Disk file system was upgraded from ext3 partition. Debug info? Sorry. all was lost because file system crashed so I could write it locally or upload anywhere. I did try to upload it using ssh but that killed my last working console so I have to do forced shutdown. So all you have now left is my bad memory that remembers back trace in ext4 mb_*cache*. Which then caused a lot of warnings about scheduling while atomic. If I can reproduce this I will next time take a photo before trying anything else. I'm just about to upgrade to the latest code even tough list of changes don't look like affecting this.