On 08/20/2012 06:31 PM, Fengguang Wu wrote:
On Mon, Aug 20, 2012 at 06:10:57PM -0700, John Stultz wrote:
On 08/20/2012 06:04 PM, Fengguang Wu wrote:
Hi John,
The below oops happens in v3.5..v3.6-rc2 and it's bisected down to commit
2a8c0883c ("time: Move xtime_nsec adjustment underflow handling timekeeping_adjust").
However linux-next is working fine. Do you have any fixes not yet sent to Linus?
Yea, there's a fix pending in tip/timers/urgent
(4e8b14526ca7fb046a81c94002c1c43b6fdf0e9b) to catch crazy values
from settimeofday or the cmos clock that might overflow a ktime_t.
That's great!
Out of curiosity, how are you triggering/reproducing this?
I boot test lots of randconfig kernels in kvm, and this oops shows up
several times in one ranconfig and some of the test boxes. I find it
pretty hard to reproduce, but managed to bisect it down by counting
1000 good boots as bisect success and running dozens of KVM instances
in parallel in several test boxes to speed up the progress. Here is one step:
Oof. That's an really impressive setup!
That said, if this happens only at boot up, and you don't have systems
with crazy cmos values, I'm not sure I see how commit
4e8b14526ca7fb046a81c94002c1c43b6fdf0e9b might fix this. So that's not
very reassuring.
As a tangent, I think this sort of big-data style testing is a really
great contribution, so thank you for setting up and doing all this work.
-john
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