Hello again,
I just finished a bisect of amd-staging-drm-next and it looks like
the hang is first introduced in edad8312cbbf9a33c86873fc4093664f150dd5c1
("drm/amdgpu: fix system hang issue during GPU reset").
It is a bit tricky, because it is commited on top of my first faulty patch
7173949df45482 ("drm/amdgpu: Fix NULL dereference in dpm sysfs handlers") so
it needs to be reverted fix the premature -INVAL.
Test case:
sudo sh -c 'echo "s 0 305 750" > /sys/class/drm/card0/device/pp_od_clk_voltage'
Results:
edad8312cbbf9a3 + revert 7173949df45482 = hang
edad8312cbbf9a3~1 + revert 7173949df45482 = no hang
Could you confirm that you get the same results?
Thanks,
Paweł Gronowski
On Fri, Jul 31, 2020 at 03:34:40PM +0200, Paweł Gronowski wrote:
> Hey Matt,
>
> I have just tested the amd-staging-drm-next branch
> (dd654c76d6e854afad716ded899e4404734aaa10) with my patches reverted
> and I can reproduce your issue with:
>
> sudo sh -c 'echo "s 0 305 750" > /sys/class/drm/card0/device/pp_od_clk_voltage'
>
> Which makes the sh hang with 100% usage.
>
> The issue does not happen on the mainline (d8b9faec54ae4bc2fff68bcd0befa93ace8256ce)
> both without and with my patches reapplied.
> So the problem must be related to some commit that is present in the
> amd-staging-drm-next but not in the mainline.
>
>
> Paweł Gronowski
>
> On Thu, Jul 30, 2020 at 06:34:14PM -0600, Matt Coffin wrote:
> > Hey Pawel,
> >
> > I did confirm that this patch *introduced* the issue both with the
> > bisect, and by testing reverting it.
> >
> > Now, there's a lot of fragile pieces in the dpm handling, so it could be
> > this patch's interaction with something else that's causing it and it
> > may well not be the fault of this code, but this is the patch that
> > introduced the issue.
> >
> > I'll have some more time tomorrow to try to get down to root cause here,
> > so maybe I'll have more to offer then.
> >
> > Thanks for taking a look,
> > Matt
> >
> > On 7/30/20 6:31 PM, Paweł Gronowski wrote:
> > > Hello Matt,
> > >
> > > Thank you for your testing. It seems that my gpu (RX 570) does not support the
> > > vc setting so I can not exactly reproduce the issue. However I did trace the
> > > code path the test case takes and it seems to correctly pass through the while
> > > loop that parses the input and fails only in amdgpu_dpm_odn_edit_dpm_table.
> > > The 'parameter' array is populated the same way as the original code did. Since
> > > the amdgpu_dpm_odn_edit_dpm_table is reached, I think that your problem is
> > > unfortunately caused by something else.
> > >
> > >
> > > Paweł Gronowski
> > >
> > > On Thu, Jul 30, 2020 at 08:49:41AM -0600, Matt Coffin wrote:
> > >> Hello all, I just did some testing with this applied, and while it no
> > >> longer returns -EINVAL, running `sudo sh -c 'echo "vc 2 2150 1195" >
> > >> /sys/class/drm/card1/device/pp_od_clk_voltage'` results in `sh` spiking
> > >> to, and staying at 100% CPU usage, with no indicating information in
> > >> `dmesg` from the kernel.
> > >>
> > >> It appeared to work at least ONCE, but potentially not after.
> > >>
> > >> This is not unique to Navi, and caused the problem on a POLARIS10 card
> > >> as well.
> > >>
> > >> Sorry for the bad news, and thanks for any insight you may have,
> > >> Matt Coffin
> > >>
> > >> On 7/29/20 8:53 PM, Alex Deucher wrote:
> > >>> On Wed, Jul 29, 2020 at 10:20 PM Paweł Gronowski <me@xxxxxxxxxx> wrote:
> > >>>>
> > >>>> Regression was introduced in commit 38e0c89a19fd
> > >>>> ("drm/amdgpu: Fix NULL dereference in dpm sysfs handlers") which
> > >>>> made the set_pp_od_clk_voltage and set_pp_power_profile_mode return
> > >>>> -EINVAL for previously valid input. This was caused by an empty
> > >>>> string (starting at the \0 character) being passed to the kstrtol.
> > >>>>
> > >>>> Signed-off-by: Paweł Gronowski <me@xxxxxxxxxx>
> > >>>
> > >>> Applied. Thanks!
> > >>>
> > >>> Alex
> > >>>
> > >>>> ---
> > >>>> drivers/gpu/drm/amd/amdgpu/amdgpu_pm.c | 9 +++++++--
> > >>>> 1 file changed, 7 insertions(+), 2 deletions(-)
> > >>>>
> > >>>> diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_pm.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_pm.c
> > >>>> index ebb8a28ff002..cbf623ff03bd 100644
> > >>>> --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_pm.c
> > >>>> +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_pm.c
> > >>>> @@ -778,12 +778,14 @@ static ssize_t amdgpu_set_pp_od_clk_voltage(struct device *dev,
> > >>>> tmp_str++;
> > >>>> while (isspace(*++tmp_str));
> > >>>>
> > >>>> - while ((sub_str = strsep(&tmp_str, delimiter)) != NULL) {
> > >>>> + while ((sub_str = strsep(&tmp_str, delimiter)) && *sub_str) {
> > >>>> ret = kstrtol(sub_str, 0, ¶meter[parameter_size]);
> > >>>> if (ret)
> > >>>> return -EINVAL;
> > >>>> parameter_size++;
> > >>>>
> > >>>> + if (!tmp_str)
> > >>>> + break;
> > >>>> while (isspace(*tmp_str))
> > >>>> tmp_str++;
> > >>>> }
> > >>>> @@ -1635,11 +1637,14 @@ static ssize_t amdgpu_set_pp_power_profile_mode(struct device *dev,
> > >>>> i++;
> > >>>> memcpy(buf_cpy, buf, count-i);
> > >>>> tmp_str = buf_cpy;
> > >>>> - while ((sub_str = strsep(&tmp_str, delimiter)) != NULL) {
> > >>>> + while ((sub_str = strsep(&tmp_str, delimiter)) && *sub_str) {
> > >>>> ret = kstrtol(sub_str, 0, ¶meter[parameter_size]);
> > >>>> if (ret)
> > >>>> return -EINVAL;
> > >>>> parameter_size++;
> > >>>> +
> > >>>> + if (!tmp_str)
> > >>>> + break;
> > >>>> while (isspace(*tmp_str))
> > >>>> tmp_str++;
> > >>>> }
> > >>>> --
> > >>>> 2.25.1
> > >>>>
> > >>>> _______________________________________________
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> > >>>
> > >>
> > >
> > >
> > >
> >
>
>
>
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