Re: memory clobber in rx path, maybe related to ath9k.

[Ben Greear <greearb@candelatech.com>]

On 10/07/2010 11:42 AM, Luis R. Rodriguez wrote:
> On Thu, Oct 7, 2010 at 11:39 AM, Ben Greear<greearb@candelatech.com>  wrote:
>> On 10/07/2010 11:29 AM, Luis R. Rodriguez wrote:
>>>
>>> On Thu, Oct 7, 2010 at 11:14 AM, Johannes Berg
>>> <johannes@sipsolutions.net>    wrote:
>>>>
>>>> On Thu, 2010-10-07 at 10:33 -0700, Ben Greear wrote:
>>>>>
>>>>> In case it helps, here is a dump of where the corrupted SKB was deleted.
>>>>
>>>> I wonder, do you have a machine with a decent IOMMU? Adding IOMMU
>>>> debugging into the mix could help you figure out if it's a DMA problem.
>>>
>>> Ben, how much traffic are you RX'ing on these virtual interfaces?
>>
>> I disabled my user-space application, and this script alone can reproduce
>> the problem fairly quickly on my system.  You will need to change some
>> of those first variables.  Just start it and wait a few minutes and
>> watch the splats show on the console :)
>>
>> Note that I am not generating any traffic, but the wpa_supplicants are
>> doing their thing of course...
>>
>> I'm using the kernel found here:
>> http://dmz2.candelatech.com/git/gitweb.cgi?p=linux.wireless-testing.ct/.git;a=summary
>>
>> It's latest wireless-testing with some of my own patches, and some
>> I've gathered from here an there.  I doubt I'm causing this problem,
>> but if you can't reproduce it with this script on your kernels,
>> I can try with base wireless-testing or whatever you are using.
>
> I'll run this now, but can you try a vanilla wireless-testing? I hear
> the latest wireless-testing is borked so maybe try (git reset --hard
> master-2010-09-29), its what I'm on.

You are liable to hit a bunch of those crashes I've been reporting
before you hit the DMA thing if you don't use latest (with Johanne's scan
locking patch).

I'm going to poke at IOMMU debugging and see what I find.

I'll start a compile of vanilla wireless-testing + scan fix as well.

Thanks,
Ben

>
>    Luis


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