[v4.12-rc1 regression] mount ext4 fs results in kernel crash on PPC64le host

[Balbir Singh]

On Thu, Jun 29, 2017 at 1:41 PM, Eryu Guan <eguan at redhat.com> wrote:
> On Thu, Jun 29, 2017 at 03:16:10AM +1000, Balbir Singh wrote:
>> On Wed, Jun 28, 2017 at 6:32 PM, Eryu Guan <eguan at redhat.com> wrote:
<snip>
>> Thanks for the excellent bug report, I am a little lost on the stack
>> trace, it shows a bad page access that we think is triggered by the
>> mmap changes? The patch changed the return type to integrate the call
>> into trace-cmd. Could you point me to the tests that can help
>> reproduce the crash. Could you also suggest how long to try the test
>> cases for?
>
> Sorry, I should have provided it in the first place. It's as simple as
> mounting an ext4 filesystem on my test ppc64le host, i.e.
>
> mkdir -p /mnt/ext4
> mkfs -t ext4 -F /dev/sda5
> mount /dev/sda5 /mnt/ext4
>

I tried this test a few times with the kernel and could not reproduce it.
Could you please share the config and compiler details, I'll retry with -rc7.

In the meanwhile, does enabling kmemleak, DEBUG_PAGE_ALLOC,
slub/slab debug, list corruption, etc catch anything at the time of the
corruption?

Thanks,
Balbir Singh.