Date: Thu, 1 Apr 2010 09:50:56 -0700
From: Greg KH <gregkh@suse.de>
To: Daniel Mack <daniel@caiaq.de>
Cc: LKML <linux-kernel@vger.kernel.org>,
	AKML <linux-arm-kernel@lists.infradead.org>,
	linux-wireless@vger.kernel.org,
	Sven Neumann <s.neumann@raumfeld.com>
Subject: Re: Memory corruption with 2.6.32.10, but not with 2.6.34-rc3
Message-ID: <20100401165056.GA1138@suse.de>
References: <20100401132156.GJ30807@buzzloop.caiaq.de>
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On Thu, Apr 01, 2010 at 03:21:56PM +0200, Daniel Mack wrote:
> Hi,
> 
> we observed repeated occurances of memory corruptions (Ooopes somewhere
> deep down in the memory mangement code) on ARM PXA300 based boards.
> 
> The systems we see this on (arch/arm/mach-pxa/raumfeld.c) feature a
> libertas chipset for WiFi, an ethernet controller (smsc9220), a USB
> fullspeed host, and NAND flash which is used as UBIFS storage.
> 
> Currently, these boards run a 2.6.32.10 kernel. After collecting
> evidences for a week or so about when and how and why the memory
> corruptions happen, I tried a 2.6.34-rc3 today and the issue seems fixed
> there. So - appearantly some important fix since 2.6.32 didn't get
> enough care to be backported to the stable branch.
> 
> The bug is rather hard to trigger. What I currently do is: after the
> system booted from NAND (UBIFS root partition), I wait for the WPA2
> secured WiFi link to get active and then download a file (~8MB) over
> WiFi to local storage. This download is done in an endless loop. Once in
> a while this crashes the 2.6.32.10 kernel instantly, sometimes it takes
> up to ~5hrs to happen.
> 
> Some findings I collected over the last weeks:
> 
>  - when calling wget with '-O /dev/null' to not write any file
>    -> does NOT crash
> 
>  - downloading via Ethernet instead of WiFi
>    -> does NOT crash
> 
>  - writing the file to either a tmpfs parition or a fatfs (on USB
>    connected external media)
>    -> DOES still crash (so it is most likely not an UBIFS issue)
> 
>  - passing --download-rate=50000 to wget (to limit the traffic
>    thruput to 50kb/s) _in_creases the probability of the crash
> 
>  - running userspace applications which heavily allocate and
>    deallocate memory doesn't seem to make the bug more likely or
>    unlikely
> 
> So my current summary is that this is related to WiFi, but OTOH it still
> only happens when file system traffic is issued.
> 
> We would like to have a fix for this annoying bug in the stable series
> (especially 2.6.32.x) as well, but I don't have much ideas about where
> to search for it. Hence, I would appreciate if maintainers could think
> about any possible commits in the described time window which haven't
> reached stable. Does the description ring anyone's bell?

I can't think of any USB specific patches that would be related to this,
sorry.

good luck,

greg k-h