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!
thanks
-john
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