Re: [Bug #13058] First hibernation attempt fails

[Jens Axboe]

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@xxxxxxxxxxxxxx>
> >>>>> 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.

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.

-- 
Jens Axboe

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