Re: [possible regression] 2.6.22 reiserfs/libata sporadically hangs on resume from hibernation

["Rafael J. Wysocki" <rjw@sisk.pl>]

On Saturday, 30 June 2007 23:34, Andrey Borzenkov wrote:
> On Sunday 01 July 2007, Rafael J. Wysocki wrote:
> > On Saturday, 30 June 2007 06:59, Andrey Borzenkov wrote:
> > > Since 2.6.18 I do not have suspend to RAM; now I am starting to lose
> > > suspend to disk :)
> > >
> > > Environment - vanilla kernel (2.6.22-rc6 currently + squashfs + single
> > > pata_ali patch to switch off DMA on CD-ROM), single root on reiserfs,
> > > libata with pata_ali driver.
> > >
> > > Until 2.6.22-rc I never had problems with hibernation. With 2.6.22-rc
> > > system hung at least once in every rcX. Up to rc6 those lockups were
> > > absolutely silent (black screen without reaction to any key). In rc6 I
> > > just got something different. After resume I got on screem:
> > >
> > > swsusp: Marking nosave pages: 000000000009f000-0000000000100000
> > > swsusp: Basic memory bitmaps created
> > > swsusp: Basic memory bitmaps freed
> > >
> > > After that it just sits there doing nothing. Ther was brief sound of HDD
> > > but I suspect it was related more to power-on. System was responding to
> > > power-on button press:
> > >
> > > ACPI Error (event-0305): No installed handler for fixed event [00000002
> > > 20070125]
> > >
> > > And SysRq was functioning.
> >
> > That probably means that there's a deadlock somewhere in there.
> >
> > > Unfortunately I do not have serial console so I
> > > copy manually stacks from several last screens of output; I have tried to
> > > make a photo but right now my kbluetooth is refusing to work at all so I
> > > cannot transfer them :( (but I suspect quality would be too bad anyway)
> > >
> > > laptop_mode D
> > > 	io_schedule+0xe/0x20
> >
> > Looks suspicious to me.  Can you identify what line of code this points to?
> >
> 
> If you could explain how to ... 

Michal has already done that. :-)

[--snip--]
> >
> > I see you're using CFQ as the default IO scheduler.  Can you please switch
> > to AS and see if that changes anything?
> >
> 
> Sure, but given that I have no idea how to reproduce the lockup, we may never 
> know whether it actually helped.

Well, if the lockup never happens with AS, that will indicate something ...

Greetings,
Rafael


-- 
"Premature optimization is the root of all evil." - Donald Knuth