netdev - Re: IOV iterator bug in net tree

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Message-Id: <20160601.174225.2184872288386003765.davem@davemloft.net>
Date:	Wed, 01 Jun 2016 17:42:25 -0700 (PDT)
From:	David Miller <davem@...emloft.net>
To:	alexander.duyck@...il.com
Cc:	netdev@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: IOV iterator bug in net tree

From: Alexander Duyck <alexander.duyck@...il.com>
Date: Fri, 27 May 2016 21:32:39 -0700

> On Fri, May 27, 2016 at 11:21 AM, Alexander Duyck
> <alexander.duyck@...il.com> 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?