Re: [Bug #13058] First hibernation attempt fails

Alan Jenkins
2009-04-17T10:46:21Z

Jens Axboe wrote:
> On Fri, Apr 17 2009, Alan Jenkins wrote:
>
>> Jens Axboe wrote:
>>
>>> On Fri, Apr 17 2009, Jens Axboe wrote:
>>>
>>>
>>>> On Fri, Apr 17 2009, Alan Jenkins wrote:
>>>>
>>>>
>>>>> Jens Axboe wrote:
>>>>>
>>>>>
>>>>>> On Thu, Apr 16 2009, Rafael J. Wysocki wrote:
>>>>>>
>>>>>>
>>>>>>
>>>>>>> This message has been generated automatically as a part of a report
>>>>>>> of recent regressions.
>>>>>>>
>>>>>>> The following bug entry is on the current list of known regressions
>>>>>>> from 2.6.29. Please verify if it still should be listed and let me know
>>>>>>> (either way).
>>>>>>>
>>>>>>>
>>>>>>> Bug-Entry : http://bugzilla.kernel.org/show_bug.cgi?id=13058
>>>>>>> Subject : First hibernation attempt fails
>>>>>>> Submitter : Alan Jenkins <alan-jenkins-cCz0Lq7MMjm9FHfhHBbuYA@public.gmane.org>
>>>>>>> Date : 2009-04-10 10:58 (7 days old)
>>>>>>> First-Bad-Commit: http://git.kernel.org/?p=linux/kernel/git/torvalds/linux-2.6.git;a=commit;h=1faa16d22877f4839bd433547d770c676d1d964c
>>>>>>> References : http://marc.info/?l=linux-kernel&m=123928022321917&w=2
>>>>>>>
>>>>>>>
>>>>>>>
>>>>>> Alan, is this still a problem?
>>>>>>
>>>>>>
>>>>>>
>>>>> Yup. Still present in v2.6.30-rc2-195-g9f76208.
>>>>>
>>>>>
>>>> Given the somewhat odd nature of the bug and the requirements to trigger
>>>> it, how confident are you in the bisection results?
>>>>
>>>> I'll try and reproduce it here.
>>>>
>>>>
>>> I can't reproduce it here. It seems very odd that an ENOMEM would happen
>>> as a consequence of the rq allocation change, it doesn't really change
>>> the allocation at all (and it'll never return -ENOMEM).
>>>
>>> Can you please recheck the git bisect results. It'd be nice if the
>>> hibernation failure would actually log where the problem occured...
>>>
>>>
>> Once I found the right conditions (wireless disabled and a specific KDE
>> session), it was 100% reproducible.
>>
>> Reverting your commit fixed the problem. I can do another test of that
>> if you like.
>>
>> My _bisection_ was not absolute, rock-solid certain because I only found
>> the right conditions half-way through. There's always the possibility I
>> would get different results if I redid it properly, from the start. But
>> I have some experience of this and took care to re-validate my upper &
>> lower bounds.
>>
>
> Well, if you can and have the time, reproducing the bisect results with
> the same conditions all the way through would definitely help.
>

I can do that, yes.

As another datapoint: I tried blindly applying the commit to 2.6.29.
The resulting kernel was able to hibernate fine the first time.

I'm going to be annoying and try something slightly different. In
theory, I should be able to find the "first bad commit" where
cherry-picking 1faa16d22 causes a problem.

> Or perhaps Rafael can suggest adding some printk()'s to catch where that
> ENOMEM is coming from. That would help, right now I basically have zero
> clue on where this might be.
>