Re: stop_machine lockup issue in 3.9.y.

[Ben Greear]

On 06/05/2013 08:46 PM, Eric Dumazet wrote:
> On Wed, 2013-06-05 at 20:41 -0700, Ben Greear wrote:
> > On 06/05/2013 08:26 PM, Eric Dumazet wrote:
> > > On Wed, 2013-06-05 at 20:14 -0700, Tejun Heo wrote:
> > >
> > > > Ah, so, that's why it's showing up now.  We probably have had the same
> > > > issue all along but it used to be masked by the softirq limiting.  Do
> > > > you care to revive the 10 iterations limit so that it's limited by
> > > > both the count and timing?  We do wanna find out why softirq is
> > > > spinning indefinitely tho.
> > >
> > > Yes, no problem, I can do that.
> >
> > Limiting it to 5000 fixes my problem, so if you wanted it larger than 10, that would
> > be fine by me.
> >
> > I can send a version of my patch easily enough if we can agree on the max number of
> > loops (and if indeed my version of the patch is acceptable).
>
> Well, 10 was the prior limit and seems really fine.
>
> The non update on jiffies seems quite exceptional condition (I hope...)
>
> We use in Google a patch triggering warning is a thread holds the cpu
> without taking care to need_resched() for more than xx ms

Well, I'm sure that patch works nicely until the clock stops moving
forward :)

I'll post a patch with limit of 10 shortly.

Thanks,
Ben



--
Ben Greear <greearb@xxxxxxxxxxxxxxx>
Candela Technologies Inc  http://www.candelatech.com

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