Re: WARNING: CPU: 1 PID: 23668 at drivers/net/wireless/intel/iwlwifi/mvm/sta.c:1539 iwl_mvm_rm_sta+0x3ce/0x450

[Luca Coelho <luca@coelho.fi>]

On Fri, 2017-03-10 at 08:41 -0700, Jens Axboe wrote:
> On 03/10/2017 08:36 AM, Luca Coelho wrote:
> > On Fri, 2017-03-10 at 08:23 -0700, Jens Axboe wrote:
> > > On 03/10/2017 05:01 AM, Luca Coelho wrote:
> > > > Hi Jens,
> > > > 
> > > > On Thu, 2017-03-09 at 21:41 -0700, Jens Axboe wrote:
> > > > > On 03/01/2017 09:10 PM, Jens Axboe wrote:
> > > > > > On 03/01/2017 08:33 PM, Luca Coelho wrote:
> > > > > > > Hi Jens,
> > > > > > > 
> > > > > > > On Mar 1, 2017 20:25, Jens Axboe <axboe@kernel.dk> wrote:
> > > > > > > 
> > > > > > >     Not that folks have been jumping all over this, but in case someone is
> > > > > > >     curious, it triggered twice here today. For those two times, the value
> > > > > > >     of mvm->pending_frames[sta_id] was 80 and 39, respectively.
> > > > > > > 
> > > > > > > Sorry for the delay, I'm on vacation now with limited internet access.
> > > > > > > But we'll take a look into this early next week at the latest.
> > > > > > > 
> > > > > > > Thanks a lot for the detailed report!
> > > > > > 
> > > > > > No worries, thanks for responding. I just wanted to ensure this wasn't
> > > > > > dropped on the floor.
> > > > > > 
> > > > > > BTW, a few more values of ->pending_frames[sta_id]:
> > > > > > 
> > > > > > $ dmesg | grep "ret="
> > > > > > [ 2334.308254] ret=39
> > > > > > [ 7915.311828] ret=80
> > > > > > [31602.317204] ret=41
> > > > > > [32139.510993] ret=54
> > > > > > [33292.917759] ret=96
> > > > > > 
> > > > > > it seems to often happen around resume.
> > > > > 
> > > > > This is still happening all the time in current -git.
> > > > 
> > > > Could you collect traces with trace-cmd, as explained in our wiki[1]?
> > > > This will probably help point out the problem.  I know it's a bit
> > > > difficult because it appears to happen randomly for you, but it's worth
> > > > trying.
> > > 
> > > Sure I can, but honestly I'm a little puzzled that nobody else can
> > > reproduce this, it happens every time I resume of switch access points.
> > > Is anyone trying to reproduce this?
> > > 
> > > I'll have to recompile with iwlwifi tracing enabled, then I'll send a trace
> > > when it happens.
> > 
> > Are you using 4.11-rc1? Or linus' master? Or...?
> 
> The trace I just sent is tip of Linus' tree. It's happened continually
> since the commit I mentioned in my initial report was merged:
> 
> commit 94c3e614df2117626fccfac8f821c66e30556384
> Author: Sara Sharon <sara.sharon@intel.com>
> Date:   Wed Dec 7 15:04:37 2016 +0200
> 
>     iwlwifi: mvm: fix pending frame counter calculation

I found the patch that fixes this issue in our internal tree.  I'll send
it out for you to try now.

The reason is that in DQA (Dynamic Queue Allocation) mode that we
introduced recently, we should not be counting the frames in the same
way as before.  The warning was introduced exactly to catch this kind of
problems.

Please let me know if it works for you!

--
Cheers,
Luca.