Your submission was sent successfully! Close

Thank you for signing up for our newsletter!
In these regular emails you will find the latest updates from Canonical and upcoming events where you can meet our team.Close

Thank you for contacting our team. We will be in touch shortly.Close

  1. Blog
  2. Article

Robin Winslow
on 28 September 2015

Prepare for when Ubuntu freezes

I routinely have at least 20 tabs open in Chrome, 10 files open in Atom (my editor of choice) and I’m often running virtual machines as well. This means my poor little X1 Carbon often runs out of memory, at which point Ubuntu completely freezes up, preventing me from doing anything at all.

Just a few days ago I had written a long post which I lost completely when my system froze, because Atom doesn’t yet recover documents after crashes.

If this sounds at all familiar to you, I now have a solution! (Although it didn’t save me in this case because it needs to be enabled first – see below.)


The magic SysRq key can run a bunch of kernel-level commands. One of these commands is called oom_kill. OOM stands for “Out of memory”, so oom_kill will kill the process taking up the most memory, to free some up. In most cases this should unfreeze Ubuntu.

You can run oom_kill from the keyboard with the following shortcut:

Except that this is disabled by default on Ubuntu:

Enabling SysRq functions

For security reasons, SysRq keyboard functions are disabled by default. To enable them, change the value in the file /etc/sysctl.d/10-magic-sysrq.conf to 1:

And to enable the new config run:

SysRq shortcut for the Thinkpad X1

Most laptops don’t have a physical SysRq key. Instead they offer a keyboard combination to emulate the key. On my Thinkpad, this is fn + s. However, there’s a quirk that the SysRq key is only “pressed” when you release.

So to run oom_kill on a Thinkpad, after enabling it, do the following:

  • Press and hold alt
  • To emulate SysRq, press fn and s keys together, then release them (keep holding alt)
  • Press f

This will kill the most expensive process (usually the browser tab running in my case), and freeup some memory.

Now, if your computer ever freezes up, you can just do this, and hopefully fix it.

(Also posted on

Related posts

Igor Ljubuncic
24 January 2024

Canonical’s recipe for High Performance Computing


In essence, High Performance Computing (HPC) is quite simple. Speed and scale. In practice, the concept is quite complex and hard to achieve. It is not dissimilar to what happens when you go from a regular car to a supercar or a hypercar – the challenges and problems you encounter at 100 km/h are vastly ...

Anthony Dillon
25 October 2023

Web team – hack week 2023

Design Article

Today, around 96% of software projects utilize open source in some way. The web team here at Canonical is passionate about Open source. We lead with an open-by-default approach and so almost everything we do and work on can be found publicly on the Canonical Github org. It is not enough to simply open our ...

Bartek Szopka
18 July 2023

Vanilla 4.0 release

Design Article

Last week we released a new major version of the Vanilla framework. Vanilla 4.0 introduces the elements of the new style used for a current rebranding of Canonical’s brochure websites, including typography changes of headings utilising new variable Ubuntu font, wider grid width, removed rounded corners, some updated colours, and updates t ...