ubsan and Dejagnu not having a big enough buffer in some cases

[Jeff Law]

On 07/20/2016 03:09 PM, Andrew Pinski wrote:
> On Wed, Jul 20, 2016 at 2:02 PM, Andrew Pinski <pinskia@gmail.com> wrote:
>> On Wed, Jul 20, 2016 at 1:32 PM, Jeff Law <law@redhat.com> wrote:
>>> On 07/20/2016 02:21 PM, Segher Boessenkool wrote:
>>>>
>>>> On Wed, Jul 20, 2016 at 12:48:09PM +0530, Senthil Kumar Selvaraj wrote:
>>>>>>
>>>>>> I see this for some of the larger C frontend tests with lots of expected
>>>>>> errors/warnings as well.
>>>>
>>>>
>>>> I also see this for tests with small output, but it happens more
>>>> often for tests with big output.
>>>>
>>>>> Are you guys getting this everytime or is it sporadic?
>>>>
>>>>
>>>> Not always, but usually.  It seems related to how busy the system is,
>>>> but that could be my imagination.
>>>>
>>>> It usually happens for a bunch of tests at the same time.
>>>>
>>>> Not always is the output just cut short: some random characters
>>>> are inserted sometimes (in the individual log files, the consolidated
>>>> log file does not have those; it looks like pointers).
>>>
>>> Hmm, there was a kernel bug a while back which had similar behavior. What
>>> kernel version are you running?
>>
>> I am running with 4.2.  Let me find the old email and see I should
>> include it in our tree (I thought we did).
>
> Found it.  It looks like it was not put in yet:
> https://bugzilla.kernel.org/show_bug.cgi?id=96311
>
> I know Jakub asked about a year ago saying it was not 4.1-rc1 yet.
> Can someone look to see if it even made it into newer kernels?
I know "a" fix is in modern Fedora kernels and I thought it came from 
upstream.

Jeff