I have a quick, (maybe naive),question about Linux kernel's output. When I issue a command, the system (Ubuntu 12.04) freezes, the serial port output of this system is as follows:

[  373.805067] BUG: soft lockup - CPU#1 stuck for 23s! [migration/1:14]
[  373.805069] BUG: soft lockup - CPU#2 stuck for 23s! [migration/2:19]
[  373.805070] BUG: soft lockup - CPU#3 stuck for 23s! [migration/3:24]

My question is:

What does [migration/1:14] mean?

I know 1 stands for the CPU#1, but I'm confused at the meaning of 14.

1 Answer 1


Processes identified as [...] are threads that run inside the kernel. Without looking too much closer, something gets stuck when migrating tasks from one CPU core to the other. This is a serious kernel problem (as you see, the machine get stuck).

If not LTS, upgrade to the latest Ubuntu. If LTS, update all, and consider upgrading. If the problem persists, collect all relevant data (exact machine model, CPU model, kernel version) and report it at the relevant Ubuntu bugtracker.

  • Hi, @vonbrand, thank you very much for your explain! Actually, I knew that. But I don't understand the meaning of 14 in the [...]. This may not be a problem of Ubuntu, because I'm hot-plugging cpus for the OS. As you pointed out, a kernel thread is migrating tasks from one cpu to anther, but the problem is how I can know which one it is migrating to?
    – Mike
    Jun 23, 2014 at 12:56

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