Messages in this thread | | | Date | Mon, 20 Aug 2012 18:46:05 -0700 | From | John Stultz <> | Subject | Re: BUG: NULL pointer dereference in shmem_evict_inode() |
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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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