Re: stop_machine lockup issue in 3.9.y.

From: Ben Greear
Date: Thu Jun 06 2013 - 17:16:13 EST

On 06/06/2013 01:55 PM, Tejun Heo wrote:
Hello, Ben.

On Wed, Jun 05, 2013 at 08:41:01PM -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.

First of all, kudos for tracking the issue down. While the removal of
looping limit in softirq handling was the direct cause for making the
problem visible, it's very bothering that we have softirq runaway.
Finding out the perpetrator shouldn't be hard. Something like the
following should work (untested). Once we know which softirq (prolly
the network one), we can dig deeper.

The patch below assumes my fix is not in the code, right?

I'll work on this, but it will probably be next week before
I have time...gotta catch up on some other things first.


Ben Greear <greearb@xxxxxxxxxxxxxxx>
Candela Technologies Inc

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