Re: [Bisected Regression in 2.6.35] A full tmpfs filesystem causeshibernation to hang

From: KOSAKI Motohiro
Date: Thu Sep 02 2010 - 21:53:39 EST


> On Friday, September 03, 2010, KOSAKI Motohiro wrote:
> > Hello,
> >
> > > > > > Like in the patch below, perhaps?
> > > > >
> > > > > Looks like fine. but I have one question. hibernate_preallocate_memory() call
> > > > > preallocate_image_memory() two times. Why do you only care latter one?
> > > > > former one seems similar risk.
> > > >
> > > > The first one is mandatory, ie. if we can't allocate the requested number of
> > > > pages at this point, we fail the entire hibernation. In that case the
> > > > performance hit doesn't matter.
> > >
> > > IOW, your patch at http://lkml.org/lkml/2010/9/2/262 is still necessary to
> > > protect against the infinite loop in that case.
> >
> > As far as I understand, we need distinguish two allocation failure.
> > 1) failure because no enough memory
> > -> yes, hibernation should fail
> > 2) failure because already allocated enough lower zone memory
> > -> why should we fail?
> >
> > If the system has a lot of memory, scenario (2) is happen frequently than (1).
> > I think we need check alloc_highmem and alloc_normal variable and call
> > preallocate_image_highmem() again instead preallocate_image_memory()
> > if we've alread allocated enough lots normal memory.
> >
> > nit?
>
> Actually I thought about that, but we don't really see hibernation fail for
> this reason. In all of the tests I carried out the requested 50% of highmem
> had been allocated before allocations from the normal zone started to be
> made, even if highmem was 100% full at that point. So this appears to be
> a theoretical issue and covering it would require us to change the algorithm
> entirely (eg. it doesn't make sense to call preallocate_highmem_fraction() down
> the road if that happens).

ok, thanks. probably I've catched your point. please feel free to use my reviewed-by
for your fix.

thanks.



--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/