Re: [net/bpf] 3051bf36c2 BUG: unable to handle kernel paging request at 0000a7cf

From: Laura Abbott
Date: Wed Mar 08 2017 - 19:24:03 EST

On 03/08/2017 02:36 PM, Kees Cook wrote:
> On Wed, Mar 8, 2017 at 2:27 PM, Daniel Borkmann <daniel@xxxxxxxxxxxxx> wrote:
>> [ 28.474232] rodata_test: test data was not read only
>> [...]
> In my tests so far, I've never been able to get rodata_test to fail
> (Qemu 2.5.0, Ubuntu). I'll retry with your .config and see if I can
> recheck under Qemu 2.7.1. Do you see these failures on real hardware?
> -Kees

FWIW, I'm seeing the same issue with qemu 2.6.2 and 2.8.0 on Fedora 24
and rawhide respectively.

I also notice that CONFIG_X86_PAE is turned off in the defconfig. If
I set CONFIG_HIGHMEM_64G which turns on CONFIG_X86_PAE the problem
goes away. I can't tell if this is an indication of magically hiding
the TLB problem or if there is an issue with !X86_PAE invalidation.