Slow to wake: watchdog: BUG: soft lockup - CPU#3

I’m running a Mid-2012 MacBook Pro 13 and Fedora is taking upwards of a couple minutes to wake from a black screen to the login screen. The system is dual booting with Mac OS and the issue only affects Fedora.

The full error is from the logs app is: watchdog: BUG: soft lockup - CPU#3 stuck for 22s! [cpuhp/3:30]

This has been happening for the past year or so but I’ve just now gotten frustrated enough to try to resolve it. If anybody has an idea as to how to solve this I’d be grateful!


Hi Steve,
I have the same problem (CPU3 waking up slowly). Have you solved the problem?
I’m afraid I’ll have to change distros because of this annoying problem.

Thank you.

Hello Steve,

i have temporary solved the problem disabling the 4th core:

In “/etc/default/grub” I have added “isolcpus=3” to “GRUB_CMDLINE_LINUX” after “…splash”

After a reboot the wake up time is now normal. But of course I lost 1 core…

P.S. Repeating the process doesn’t work anymore, I have to edit manually the /sys/devices/system/cpu/cpu3/online file putting 0 inside


Related topic

I have MBP 17" early 2011, and in my case that was CPU 5, 6, 7. Maybe it is better to switch on/off all of them(1-7) ?
See this post

I wrote this gist: