Re: [PATCH 00/11] 3.2-stable: Fix for leapsecond caused hrtimer/futexissue

From: John Stultz
Date: Mon Jul 23 2012 - 15:51:53 EST

On 07/19/2012 01:48 PM, Christoph Biedl wrote:
John Stultz wrote...

Attached is the test case I used to reproduce and test the solution
to the hard-hang deadlock.
I was wondering whether anybody managed to crash a virtualbox guest
using your program. No avail, using version 4.1.18 on the host and the
guest kernel running several 3.0.x (x < 38) kernels on both x32 and
x64, the guest utilies were stopped. Rather a fun fact I guess but I
wanted to let you know.

I've been able to crash a kvm guest with an unpatched kernel with my test. The issue requires that the adding of the hrtimer causes the clockevent to be reprogrammed. This usually happens if there's no timers that expire sooner then the leapsecond timer. So if there are drivers that set frequent timers, or set timers right before the leapsecond, it may be difficult to trigger this issue.

Lowering HZ or adding more vcpus might help if you really want to be able to trigger the issue.

All real hardware tested, including a dockstar on armel, crashed as
predicted, while 3.0.38-rc1 was immune.
Great to hear!


To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at
Please read the FAQ at