The kernel writes about more than disks: when a program touches memory that is not its own, the kernel ends it and leaves a line in the same buffer.
In ~/crash-lab the thumbgen program makes thumbnails of the photos in photos/. Run it.
Run thumbgen
In ~/crash-lab, run thumbgen, check its exit status and find it in the kernel buffer.
First, predict
thumbgen will crash on the first photo. What will echo $? print?
Now start the exercise, run the command and compare your prediction with the output.