Re: IOV iterator bug in net tree

From: Alexander Duyck
Date: Wed Jun 01 2016 - 20:54:14 EST

On Wed, Jun 1, 2016 at 5:42 PM, David Miller <davem@xxxxxxxxxxxxx> wrote:
> From: Alexander Duyck <alexander.duyck@xxxxxxxxx>
> Date: Fri, 27 May 2016 21:32:39 -0700
>> On Fri, May 27, 2016 at 11:21 AM, Alexander Duyck
>> <alexander.duyck@xxxxxxxxx> wrote:
>>> I started out this morning by trying to run DevStack on the latest
>>> "net' kernel and it looks like I am hanging on some sort of locking
>>> problem with RabbitMQ. Specifically I am seeing one CPU jump to 100%
>>> with perf showing that I am spinning on a lock.
>>> I'm working to bisect it now, but just thought I would put it out
>>> there if anybody had already root caused this issue. Below is a few
>>> traces to the spin lock call on the spinning CPU:
>> I misread the perf trace. I wasn't spinning on a lock I was spinning
>> on the IOV iterator. It just happened to push the lock to the top of
>> the perf trace. I bisected it down to the recent change in
>> iterate_and_advance which was already fixed in Linus's tree in commit
>> 19f18459330f "do 'fold checks into iterate_and_advance()" right'.
> Since I resynced both of my trees with Linus's, this should be resolved
> now, right?

Yes, I pulled the latest net tree a few hours ago and it is working
without any issues.


- Alex