Re: Regression: memory corruption on Atmel SAMA5D31

From: <Tudor.Ambarus@microchip.com>
To: <regressions@leemhuis.info>, <peda@axentia.se>,
	<Nicolas.Ferre@microchip.com>, <alexandre.belloni@bootlin.com>
Cc: <du@axentia.se>, <Patrice.Vilchez@microchip.com>,
	<Cristian.Birsan@microchip.com>,
	<Ludovic.Desroches@microchip.com>, <linux-kernel@vger.kernel.org>,
	<linux-arm-kernel@lists.infradead.org>,
	<gregkh@linuxfoundation.org>, <saravanak@google.com>
Subject: Re: Regression: memory corruption on Atmel SAMA5D31
Date: Mon, 20 Jun 2022 08:43:51 +0000	[thread overview]
Message-ID: <6b1bae01-d8fb-1676-3dee-9d5d376e37f1@microchip.com> (raw)
In-Reply-To: <bfb4cb27-e2e1-e709-1c27-d938e4d30eab@leemhuis.info>

On 6/20/22 10:04, Thorsten Leemhuis wrote:
> EXTERNAL EMAIL: Do not click links or open attachments unless you know the content is safe
> 
> On 18.05.22 09:51, Peter Rosin wrote:
>> 2022-05-18 at 08:21, Tudor.Ambarus@microchip.com wrote:
>>> On 5/17/22 17:50, Peter Rosin wrote:
>>>> EXTERNAL EMAIL: Do not click links or open attachments unless you know the content is safe
>>>>
>>>> 2022-04-11 at 08:21, Tudor.Ambarus@microchip.com wrote:
>>>>> There are some concurrency bugs in the at-hdmac (DMA) driver, I'm handling them
>>>>> and will come with a resolution. Disabling the DMA showed the bug is no more
>>>>> reproducible.
>>>>
>>>> Any news?
>>>
>>> I'm now allocated on this, so I started looking around what has to be done.
>>> I'm thinking of using virt-dma to manage the channels and the request queues.
>>> Will get back to you after I'll have something working.
>>
>> Sounds good, thanks!
> 
> That was about a month ago. Has any progress been made to get this
> regression fixed?

Hi, Thorsten, Peter,

I was mostly out of office last month, and I'll still be offline this week.
I made some progress, tried to address the bugs in an incremental way. I  now
encounter the memory corruption less often, but I still hit it. I made some
drafts at [1] if someone is curios. Anyway, I'm modifying the driver to use
virt-dma and also I'm trying to move the election of a new transfer in the
irq handler instead of in tasklet. I couldn't find a quick non-invasive fix,
so still in progress.

Cheers,
ta

git@github.com:ambarus/linux-0day.git, branch dma-regression-hdmac-v5.18-rc7-4th-attempt

> 
> Ciao, Thorsten (wearing his 'the Linux kernel's regression tracker' hat)
> 
> P.S.: As the Linux kernel's regression tracker I deal with a lot of
> reports and sometimes miss something important when writing mails like
> this. If that's the case here, don't hesitate to tell me in a public
> reply, it's in everyone's interest to set the public record straight.
> 
> #regzbot poke
> 
> 