system hang with backports-20150511/20150525

Michal Kazior michal.kazior at
Mon Jun 1 22:20:05 PDT 2015

On 1 June 2015 at 21:42, Marty Faltesek <mfaltesek at> wrote:
> I disabled IEEE80211_HW_SUPPORT_FAST_XMIT before, and still saw the
> hang. I repeated today to confirm.

Thanks for checking.

> I added the extra ath10k debug flags you requested, and it causes a
> system reset without any messages, very soon after the last hbeat
> timestamp. I've uploaded  log "crash." to

I guess serial console gave up which isn't really surprising :( Thanks
for checking anyway.

> Any advice on how to bisect when using backports?

Sure. Generally you'll need to do the bisect on your linux-next tree
which you use to generate backports:

 git clone git://
 git clone git://
 cd linux-next
 git bisect start
 git bisect good a3da0fb6
 git bisect bad f17107c
 # repeat:
 cd ../backports
 ./ --clean --git-revision HEAD ../linux-next ../backports-output/
 cd ../backports-output
 # configure, make, test
 cd ../linux-next
 git bisect <good|bad> # "good" if problem doesn't reproduce, "bad" if it does
 # goto repeat


> On Mon, Jun 1, 2015 at 4:27 AM, Michal Kazior <michal.kazior at> wrote:
>> On 1 June 2015 at 09:13, Kalle Valo <kvalo at> wrote:
>>> Michal Kazior <michal.kazior at> writes:
>>>> +ath10k list
>>>> On 1 June 2015 at 03:37, Marty Faltesek <mfaltesek at> wrote:
>>>>> Starting with backports-20150511, and continuing with
>>>>> backports-20150525, we see frequent system hangs. backports-20150424
>>>>> had no issue.
>>>> I don't see such binary releases on
>>>> Hence I don't know what kernel you've backported the drivers from and
>>>> I can't compare anything.
>>>> Can you provide more details, please?
>>> I suspect it's from here:
>>> The backports project pages are a bit confusing and that location is
>>> hard to find.
>> Oh, thanks!
>> Hmm.. There was a ton of changes between 20150424 and 20150511. For
>> one, ath10k started to use chanctx API and FAST_XMIT. But it's not a
>> given these two are to blame.
>> The latter can be easily disabled by removing
>> IEEE80211_HW_SUPPORT_FAST_XMIT from ar->hw->flags in ath10k's mac.c.
>> The former.. not so easy. I'd be awesome if you could do a git bisect.
>> The commit ids are a3da0fb6(good) f17107c(bad) (you need linux-next
>> git repo including its tags for these ids to be resolvable).
>> Michał

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