linux-kernel - Re: CONFIG_ANDROID (was: rcu_sched detected expedited stalls in amdgpu after suspend)

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Date:   Mon, 4 Jul 2022 13:30:50 +0200
From:   Christian König <christian.koenig@....com>
To:     Uladzislau Rezki <urezki@...il.com>,
        "Alex Xu (Hello71)" <alex_y_xu@...oo.ca>
Cc:     wireguard@...ts.zx2c4.com, "Jason A. Donenfeld" <Jason@...c4.com>,
        Joel Fernandes <joel@...lfernandes.org>, paulmck@...nel.org,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Xinhui.Pan@....com, linux-kernel@...r.kernel.org,
        amd-gfx@...ts.freedesktop.org,
        Suren Baghdasaryan <surenb@...gle.com>, rcu@...r.kernel.org,
        Hridya Valsaraju <hridya@...gle.com>,
        Arve Hjønnevåg <arve@...roid.com>,
        Theodore Ts'o <tytso@....edu>, alexander.deucher@....com,
        Todd Kjos <tkjos@...roid.com>, uladzislau.rezki@...y.com,
        Martijn Coenen <maco@...roid.com>, christian.koenig@....com,
        Christian Brauner <christian@...uner.io>
Subject: Re: CONFIG_ANDROID (was: rcu_sched detected expedited stalls in
 amdgpu after suspend)

Hi guys,

Am 28.06.22 um 22:11 schrieb Uladzislau Rezki:
>> Excerpts from Paul E. McKenney's message of June 28, 2022 2:54 pm:
>>> All you need to do to get the previous behavior is to add something like
>>> this to your defconfig file:
>>>
>>> CONFIG_RCU_EXP_CPU_STALL_TIMEOUT=21000
>>>
>>> Any reason why this will not work for you?

sorry for jumping in so later, I was on vacation for a week.

Well when any RCU period is longer than 20ms and amdgpu in the backtrace 
my educated guess is that we messed up some timeout waiting for the hw.

We usually do wait a few us, but it can be that somebody is waiting for 
ms instead.

So there are some todos here as far as I can see and It would be helpful 
to get a cleaner backtrace if possible.

Regards,
Christian.