linux-kernel - Re: [PATCH] drm/ttm: fix error handling in ttm_bo_handle_move

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Message-ID: <7354cd94-06bf-ec36-4539-c3570c1775ae@gmail.com>
Date:   Wed, 16 Jun 2021 13:00:38 +0200
From:   Christian König <ckoenig.leichtzumerken@...il.com>
To:     Dan Carpenter <dan.carpenter@...cle.com>
Cc:     Thomas Hellstr <C3@...nda>, B6@...nda,
        m <thomas.hellstrom@...ux.intel.com>,
        Huang Rui <ray.huang@....com>, David Airlie <airlied@...ux.ie>,
        Daniel Vetter <daniel@...ll.ch>,
        dri-devel@...ts.freedesktop.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] drm/ttm: fix error handling in ttm_bo_handle_move_mem()



Am 16.06.21 um 11:36 schrieb Dan Carpenter:
> On Wed, Jun 16, 2021 at 10:47:14AM +0200, Christian König wrote:
>>
>> Am 16.06.21 um 10:37 schrieb Dan Carpenter:
>>> On Wed, Jun 16, 2021 at 08:46:33AM +0200, Christian König wrote:
>>>> Sending the first message didn't worked, so let's try again.
>>>>
>>>> Am 16.06.21 um 08:30 schrieb Dan Carpenter:
>>>>> There are three bugs here:
>>>>> 1) We need to call unpopulate() if ttm_tt_populate() succeeds.
>>>>> 2) The "new_man = ttm_manager_type(bdev, bo->mem.mem_type);" assignment
>>>>>       was wrong and it was really assigning "new_mem = old_mem;".  There
>>>>>       is no need for this assignment anyway as we already have the value
>>>>>       for "new_mem".
>>>>> 3) The (!new_man->use_tt) condition is reversed.
>>>>>
>>>>> Fixes: ba4e7d973dd0 ("drm: Add the TTM GPU memory manager subsystem.")
>>>>> Signed-off-by: Dan Carpenter <dan.carpenter@...cle.com>
>>>>> ---
>>>>> This is from reading the code and I can't swear that I have understood
>>>>> it correctly.  My nouveau driver is currently unusable and this patch
>>>>> has not helped.  But hopefully if I fix enough bugs eventually it will
>>>>> start to work.
>>>> Well NAK, the code previously looked quite well and you are breaking it now.
>>>>
>>>> What's the problem with nouveau?
>>>>
>>> The new Firefox seems to excersize nouveau more than the old one so
>>> when I start 10 firefox windows it just hangs the graphics.
>>>
>>> I've added debug code and it seems like the problem is that
>>> nv50_mem_new() is failing.
>> Sounds like it is running out of memory to me.
>>
>> Do you have a dmesg?
>>
> At first there was a very straight forward use after free bug which I
> fixed.
> https://lore.kernel.org/nouveau/YMinJwpIei9n1Pn1@mwanda/T/#u
>
> But now the use after free is gone the only thing in dmesg is:
> "[TTM] Buffer eviction failed".  And I have some firmware missing.
>
> [  205.489763] rfkill: input handler disabled
> [  205.678292] nouveau 0000:01:00.0: Direct firmware load for nouveau/nva8_fuc084 failed with error -2
> [  205.678300] nouveau 0000:01:00.0: Direct firmware load for nouveau/nva8_fuc084d failed with error -2
> [  205.678302] nouveau 0000:01:00.0: msvld: unable to load firmware data
> [  205.678304] nouveau 0000:01:00.0: msvld: init failed, -19
> [  296.150632] [TTM] Buffer eviction failed
> [  417.084265] [TTM] Buffer eviction failed
> [  447.295961] [TTM] Buffer eviction failed
> [  510.800231] [TTM] Buffer eviction failed
> [  556.101384] [TTM] Buffer eviction failed
> [  616.495790] [TTM] Buffer eviction failed
> [  692.014007] [TTM] Buffer eviction failed
>
> The eviction failed message only shows up a minute after the hang so it
> seems more like a symptom than a root cause.

Yeah, look at the timing. What happens is that the buffer eviction timed 
out because the hardware is locked up.

No idea what that could be. It might not even be kernel related at all.

Regards,
Christian.

>
> regards,
> dan carpenter
>