One day after announcing the availability of the first Beta images of the forthcoming Ubuntu Snappy Core 16 operating system for IoT and embedded devices, Canonical's Michael Vogt informed us about the release of the Snapd 2.14.2 Snappy daemon.
Snapd is the brain behind the Snappy technologies used for installing and running Snap universal binary packages in Ubuntu Linux and other GNU/Linux distributions that support it, and Snapd 2.14.2 is currently the most stable and advanced version, available now for Ubuntu 16.04 LTS (Xenial Xerus) and Fedora 24 (in the COPR repos).
FreedomPenguin: If you've used Solus at all in the past couple of months you have probably noticed a deluge of changes and bug fixes.
The Logical Volume Manager can create virtual block devices that refer to specific parts of other block devices, right? I got curious what happens if you were to create a virtual block device that refers to itself. So I decided to give it a try.
First, I did ls -l /dev/dm* to find the highest-numbered LVM device; dm-2 was the last one, with major:minor 254:2. I figured that the next one would most likely be 254:3. I typed dmsetup create circular, meaning to create a virtual block device with the identifier circular. I entered 0 1 linear 254:3 0 for the table.
What happened was kind of interesting. I hit Ctrl+D to tell it I was done inputting, but nothing happened. I tried pressing it a few more times, still nothing. So I hit Ctrl+C to exit and did it again. This time Ctrl+D worked, but it gave me a "device or resource busy" error.
Apparently one of those times the command actually did complete successfully, however. Because I soon noticed my system freeze completely, with the mouse cursor not working. A while later I noticed the cursor moved a little bit, so I knew the system wasn't completely frozen. I hit Ctrl+Alt+F1 to switch to a TTY so I could figure out what was going on. The screen turned black, but the login prompt didn't appear. Shortly after, I noticed a blinking light on my laptop. It was the caps lock light. Kernel panic, I'm guessing a stack overflow.
I rebooted and looked at /var/log/syslog. There was no mention of a kernel panic (I looked it up and apparently these aren't logged because writing to the file system in that situation would be risky) but I did see a line saying that "'devices/virtual/block/dm-3' is taking a long time", and a few lines higher I saw the unnecessarily-evil-sounding "Out of memory: kill process 12164 (firefox) score 10 or sacrifice child". (The message was from a daemon, so I can't say I'm surprised.)
Has anyone else ever tried this, or am I the first?
EDIT: Just came across this message. Looks like someone else had tried the same thing via a similar method.submitted by /u/flarn2006