[LEAPSECS] Good description of Linux kernel bugs related to leap seconds

Hal Murray hmurray at megapathdsl.net
Mon Jul 2 22:53:59 EDT 2012

>From Steven Bellovin, on NANOG:

See http://landslidecoding.blogspot.com/2012/07/linuxs-leap-second-deadlocks

I've been hoping somebody would post a good summary like that. It covers 5
different bugs.

I'd split them into 3 clumps. The first clump is kernel deadlocks. As often
happens with hard problems, fixing it here breaks it over there. That's the
first 3 bugs.

The 4th bug explains the CPU load spikes. A kernel bug broke futex-es. They
are typically used in spin-lock like loops from user code. I don't
understand the details. Setting the time (to any value) fixes the kernel
problem so everything starts to work normally again. (No need to reboot.)

The 5th bug is still a mystery.

Also from NANOG:

> If folks have not read it, I would suggest reading Normal Accidents by

> Charles Perrow.

I agree. This is a good excuse to find my copy and read it again. Yes, it's
very good, but not directly related to leap seconds.

These are my opinions. I hate spam.

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