On 03/01/2018 11:36, Thomas Gleixner wrote:
On Wed, 3 Jan 2018, Guillaume Tucker wrote:
On 03/01/18 09:48, Thomas Gleixner wrote:
Well, it turns out this is not exactly a conflict as there's a subtle difference between the qemu devices in lab-mhart and in lab-collabora. The ones in lab-collabora are configured to use KVM, and it looks like the ones in lab-mhart aren't.
So this job with KVM enabled passes in lab-collabora:
https://lava.collabora.co.uk/scheduler/job/1032358
but it fails if I tell LAVA (qemu) to disable KVM:
https://lava.collabora.co.uk/scheduler/job/1032359
with the same panic as in lab-mhart. It seems like it's failing to return from an interrupt:
http://lava.streamtester.net/scheduler/job/87308
[ 2.678828] ? native_iret+0x7/0x7 [ 2.679208] WARNING: can't dereference iret registers at 00000000ffc66068 for ip page_fault+0x11/0x60
This triggered an automated bisection on kernelci.org, please see the results below.
I may run another bisection with this config enabled earlier in the history to track down the actual change in the code that introduced the issue, let me know if it's worth doing.
No, because before that commit not all pieces are in place.
Can you please try the failing kernel with pti=off on the command line?
It does boot with pti=off (and KVM disabled):
So it's a qemu issue. Added qemu folks on Cc.
Reproduced, thanks. I will look into it.
Paolo