Re: [PATCH] mac80211: Fix deadlock in ieee80211_do_stop.

[Ben Greear <greearb@candelatech.com>]

On 12/09/2010 08:17 AM, Tejun Heo wrote:
> On 12/09/2010 03:46 PM, Tejun Heo wrote:
>>> Right, so we're flushing here under RTNL ... I believe this is the one
>>> that Ben hacked up to not flush or so?
>>
>> He made it to cancel instead of flush.
>
> This makes me think that it's more likely to be a problem in the
> flush_work() implementation.  I went over the code carefully again but
> couldn't find anything suspicious.  Plus, most of the implementation
> is shared between cancel and flush.
>
> I'm gonna write some test code and see whether the flush code behaves
> as expected but in the mean time can you please apply the following
> patch, trigger the problem and report the kernel log?  Also, please
> include the sysrq task dump.  Let's see whether the worker is always
> stuck at the same spot.

I saw a brief hang today, and did a sysrq-t, and then saw the timer
printout you added here.  But, I think that was caused by sysrq-t.
The system recovered and ran fine.

The second time (after several hours of rebooting), the hang was worse
and the system ran OOM after maybe 30 seconds.  I did a sysrq-t then.

I see quite a few printouts from your debug message, but all of them
after things start going OOM, and after sysrq-t.

Here's the console capture:


http://www.candelatech.com/~greearb/minicom_ath9k_log4.txt


Let me know if you need more traces like this if I hit it again.

Thanks,
Ben

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