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

[Khalid Aziz]

On 1/11/22 17:49, sean.wang@xxxxxxxxxxxx wrote:
> From: Sean Wang <sean.wang@xxxxxxxxxxxx>
>
> > 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@xxxxxxxxxxxxxxx>
> > >
> > > 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@xxxxxxxxxxxxxxx>
> > > ---
> > >    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@xxxxxxxxx/

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