netdev - Re: [Bug] mt7921e driver in 5.16 causes kernel panic

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Date:   Tue, 11 Jan 2022 19:16:26 -0700
From:   Khalid Aziz <khalid@...ehiking.org>
To:     sean.wang@...iatek.com
Cc:     greearb@...delatech.com, nbd@....name,
        lorenzo.bianconi83@...il.com, Ryder.Lee@...iatek.com,
        Shayne.Chen@...iatek.com, kvalo@...nel.org, davem@...emloft.net,
        kuba@...nel.org, matthias.bgg@...il.com,
        linux-kernel@...r.kernel.org, netdev@...r.kernel.org,
        linux-wireless@...r.kernel.org, linux-mediatek@...ts.infradead.org
Subject: Re: [Bug] mt7921e driver in 5.16 causes kernel panic

On 1/11/22 17:49, sean.wang@...iatek.com wrote:
> From: Sean Wang <sean.wang@...iatek.com>
> 
>> On 1/11/22 16:31, Ben Greear wrote:
>>> On 1/11/22 3:17 PM, Khalid Aziz wrote:
>>>> I am seeing an intermittent bug in mt7921e driver. When the driver
>>>> module is loaded and is being initialized, almost every other time it
>>>> seems to write to some wild memory location. This results in driver
>>>> failing to initialize with message "Timeout for driver own" and at
>>>> the same time I start to see "Bad page state" messages for random
>>>> processes. Here is the relevant part of dmesg:
>>>
>>> Please see if this helps?
>>>
>>> From: Ben Greear <greearb@...delatech.com>
>>>
>>> If the nic fails to start, it is possible that the reset_work has
>>> already been scheduled.  Ensure the work item is canceled so we do not
>>> have use-after-free crash in case cleanup is called before the work
>>> item is executed.
>>>
>>> This fixes crash on my x86_64 apu2 when mt7921k radio fails to work.
>>> Radio still fails, but OS does not crash.
>>>
>>> Signed-off-by: Ben Greear <greearb@...delatech.com>
>>> ---
>>>    drivers/net/wireless/mediatek/mt76/mt7921/main.c | 1 +
>>>    1 file changed, 1 insertion(+)
>>>
>>> diff --git a/drivers/net/wireless/mediatek/mt76/mt7921/main.c
>>> b/drivers/net/wireless/mediatek/mt76/mt7921/main.c
>>> index 6073bedaa1c08..9b33002dcba4a 100644
>>> --- a/drivers/net/wireless/mediatek/mt76/mt7921/main.c
>>> +++ b/drivers/net/wireless/mediatek/mt76/mt7921/main.c
>>> @@ -272,6 +272,7 @@ static void mt7921_stop(struct ieee80211_hw *hw)
>>>
>>>        cancel_delayed_work_sync(&dev->pm.ps_work);
>>>        cancel_work_sync(&dev->pm.wake_work);
>>> +    cancel_work_sync(&dev->reset_work);
>>>        mt76_connac_free_pending_tx_skbs(&dev->pm, NULL);
>>>
>>>        mt7921_mutex_acquire(dev);
>>
>> Hi Ben,
>>
>> Unfortunately that did not help. I still saw the same messages and a kernel panic. I do not see this bug if I power down the laptop before booting it up, so mt7921_stop() would make sense as the reasonable place to fix it.
> 
> Hi, Khalid
> 
> Could you try the patch below? It should be helpful to your issue
> 
> https://patchwork.kernel.org/project/linux-wireless/patch/70e27cbc652cbdb78277b9c691a3a5ba02653afb.1641540175.git.objelf@gmail.com/

Hi Sean,

That worked! I tried 5 reboots back-to-back after applying your patch 
without powering down my laptop. There were no error messages, kernel 
came up every time and wifi worked.

Thanks,
Khalid