Regression on drm-tip

Regression on drm-tip

[Borah, Chaitanya Kumar]

Hello Lu,

Hope you are doing well. I am Chaitanya from the linux graphics team in Intel.

This mail is regarding a regression we are seeing in our CI runs[1] on drm-tip repository.

`````````````````````````````````````````````````````````````````````````````````
<4>[    2.856622] WARNING: possible circular locking dependency detected
<4>[    2.856631] 6.14.0-rc5-CI_DRM_16217-gc55ef90b69d3+ #1 Tainted: G          I       
<4>[    2.856642] ------------------------------------------------------
<4>[    2.856650] swapper/0/1 is trying to acquire lock:
<4>[    2.856657] ffffffff8360ecc8 (iommu_probe_device_lock){+.+.}-{3:3}, at: iommu_probe_device+0x1d/0x70
<4>[    2.856679] 
                  but task is already holding lock:
<4>[    2.856686] ffff888102ab6fa8 (&device->physical_node_lock){+.+.}-{3:3}, at: intel_iommu_init+0xea1/0x1220
`````````````````````````````````````````````````````````````````````````````````
Details log can be found in [2].

After bisecting the tree, the following patch [3] seems to be the first "bad" commit

`````````````````````````````````````````````````````````````````````````````````````````````````````````
commit b150654f74bf0df8e6a7936d5ec51400d9ec06d8
Author: Lu Baolu mailto:baolu.lu@linux.intel.com
Date:   Fri Feb 28 18:27:26 2025 +0800

    iommu/vt-d: Fix suspicious RCU usage

`````````````````````````````````````````````````````````````````````````````````````````````````````````

We also verified that if we revert the patch the issue is not seen.

Could you please check why the patch causes this regression and provide a fix if necessary?

Gitlab issue for the regression is [4].

Thank you.

Regards

Chaitanya

[1] https://intel-gfx-ci.01.org/tree/drm-tip/combined-alt.html?
[2] https://intel-gfx-ci.01.org/tree/drm-tip/CI_DRM_16276/fi-kbl-8809g/boot0.txt
[3] https://cgit.freedesktop.org/drm-tip/commit/?id=b150654f74bf0df8e6a7936d5ec51400d9ec06d8
[4] https://gitlab.freedesktop.org/drm/i915/kernel/-/issues/13818

Regards

Chaitanya

Re: Regression on drm-tip

[Baolu Lu]

On 2025/3/13 16:51, Borah, Chaitanya Kumar wrote:
> Hello Lu,
> 
> Hope you are doing well. I am Chaitanya from the linux graphics team in Intel.
> 
> This mail is regarding a regression we are seeing in our CI runs[1] on drm-tip repository.
> 
> `````````````````````````````````````````````````````````````````````````````````
> <4>[    2.856622] WARNING: possible circular locking dependency detected
> <4>[    2.856631] 6.14.0-rc5-CI_DRM_16217-gc55ef90b69d3+ #1 Tainted: G          I
> <4>[    2.856642] ------------------------------------------------------
> <4>[    2.856650] swapper/0/1 is trying to acquire lock:
> <4>[    2.856657] ffffffff8360ecc8 (iommu_probe_device_lock){+.+.}-{3:3}, at: iommu_probe_device+0x1d/0x70
> <4>[    2.856679]
>                    but task is already holding lock:
> <4>[    2.856686] ffff888102ab6fa8 (&device->physical_node_lock){+.+.}-{3:3}, at: intel_iommu_init+0xea1/0x1220
> `````````````````````````````````````````````````````````````````````````````````
> Details log can be found in [2].
> 
> After bisecting the tree, the following patch [3] seems to be the first "bad" commit
> 
> `````````````````````````````````````````````````````````````````````````````````````````````````````````
> commit b150654f74bf0df8e6a7936d5ec51400d9ec06d8
> Author: Lu Baolumailto:baolu.lu@linux.intel.com
> Date:   Fri Feb 28 18:27:26 2025 +0800
> 
>      iommu/vt-d: Fix suspicious RCU usage
> 
> `````````````````````````````````````````````````````````````````````````````````````````````````````````
> 
> We also verified that if we revert the patch the issue is not seen.
> 
> Could you please check why the patch causes this regression and provide a fix if necessary?

Sure. I will look into this issue.

Thanks,
baolu

Re: Regression on drm-tip

[Baolu Lu]

On 2025/3/13 16:51, Borah, Chaitanya Kumar wrote:
> Hello Lu,
> 
> Hope you are doing well. I am Chaitanya from the linux graphics team in Intel.
> 
> This mail is regarding a regression we are seeing in our CI runs[1] on drm-tip repository.
> 
> `````````````````````````````````````````````````````````````````````````````````
> <4>[    2.856622] WARNING: possible circular locking dependency detected
> <4>[    2.856631] 6.14.0-rc5-CI_DRM_16217-gc55ef90b69d3+ #1 Tainted: G          I
> <4>[    2.856642] ------------------------------------------------------
> <4>[    2.856650] swapper/0/1 is trying to acquire lock:
> <4>[    2.856657] ffffffff8360ecc8 (iommu_probe_device_lock){+.+.}-{3:3}, at: iommu_probe_device+0x1d/0x70
> <4>[    2.856679]
>                    but task is already holding lock:
> <4>[    2.856686] ffff888102ab6fa8 (&device->physical_node_lock){+.+.}-{3:3}, at: intel_iommu_init+0xea1/0x1220
> `````````````````````````````````````````````````````````````````````````````````
> Details log can be found in [2].
> 
> After bisecting the tree, the following patch [3] seems to be the first "bad" commit
> 
> `````````````````````````````````````````````````````````````````````````````````````````````````````````
> commit b150654f74bf0df8e6a7936d5ec51400d9ec06d8
> Author: Lu Baolumailto:baolu.lu@linux.intel.com
> Date:   Fri Feb 28 18:27:26 2025 +0800
> 
>      iommu/vt-d: Fix suspicious RCU usage
> 
> `````````````````````````````````````````````````````````````````````````````````````````````````````````
> 
> We also verified that if we revert the patch the issue is not seen.
> 
> Could you please check why the patch causes this regression and provide a fix if necessary?

Can you please take a quick test to check if the following fix works?

diff --git a/drivers/iommu/intel/dmar.c b/drivers/iommu/intel/dmar.c
index e540092d664d..06debeaec643 100644
--- a/drivers/iommu/intel/dmar.c
+++ b/drivers/iommu/intel/dmar.c
@@ -2051,8 +2051,13 @@ int enable_drhd_fault_handling(unsigned int cpu)
                 if (iommu->irq || iommu->node != cpu_to_node(cpu))
                         continue;

+               /*
+                * Call dmar_alloc_hwirq() with dmar_global_lock held,
+                * could cause possible lock race condition.
+                */
+               up_read(&dmar_global_lock);
                 ret = dmar_set_interrupt(iommu);
-
+               down_read(&dmar_global_lock);
                 if (ret) {
                         pr_err("DRHD %Lx: failed to enable fault, 
interrupt, ret %d\n",
                                (unsigned long long)drhd->reg_base_addr, 
ret);

Thanks,
baolu

RE: Regression on drm-tip

[Borah, Chaitanya Kumar]

> -----Original Message-----
> From: Baolu Lu <baolu.lu@linux.intel.com>
> Sent: Thursday, March 13, 2025 7:53 PM
> To: Borah, Chaitanya Kumar <chaitanya.kumar.borah@intel.com>
> Cc: baolu.lu@linux.intel.com; intel-gfx@lists.freedesktop.org; intel-
> xe@lists.freedesktop.org; iommu@lists.linux.dev
> Subject: Re: Regression on drm-tip
> 
> On 2025/3/13 16:51, Borah, Chaitanya Kumar wrote:
> > Hello Lu,
> >
> > Hope you are doing well. I am Chaitanya from the linux graphics team in
> Intel.
> >
> > This mail is regarding a regression we are seeing in our CI runs[1] on drm-tip
> repository.
> >
> > ``````````````````````````````````````````````````````````````````````
> > ``````````` <4>[    2.856622] WARNING: possible circular locking
> > dependency detected <4>[    2.856631]
> > 6.14.0-rc5-CI_DRM_16217-gc55ef90b69d3+ #1 Tainted: G          I <4>[
> > 2.856642] ------------------------------------------------------
> > <4>[    2.856650] swapper/0/1 is trying to acquire lock:
> > <4>[    2.856657] ffffffff8360ecc8
> > (iommu_probe_device_lock){+.+.}-{3:3}, at:
> > iommu_probe_device+0x1d/0x70 <4>[    2.856679]
> >                    but task is already holding lock:
> > <4>[    2.856686] ffff888102ab6fa8
> > (&device->physical_node_lock){+.+.}-{3:3}, at:
> > intel_iommu_init+0xea1/0x1220
> > ``````````````````````````````````````````````````````````````````````
> > ```````````
> > Details log can be found in [2].
> >
> > After bisecting the tree, the following patch [3] seems to be the
> > first "bad" commit
> >
> > ``````````````````````````````````````````````````````````````````````
> > ```````````````````````````````````
> > commit b150654f74bf0df8e6a7936d5ec51400d9ec06d8
> > Author: Lu Baolumailto:baolu.lu@linux.intel.com
> > Date:   Fri Feb 28 18:27:26 2025 +0800
> >
> >      iommu/vt-d: Fix suspicious RCU usage
> >
> > ``````````````````````````````````````````````````````````````````````
> > ```````````````````````````````````
> >
> > We also verified that if we revert the patch the issue is not seen.
> >
> > Could you please check why the patch causes this regression and provide a
> fix if necessary?
> 
> Can you please take a quick test to check if the following fix works?
> 
> diff --git a/drivers/iommu/intel/dmar.c b/drivers/iommu/intel/dmar.c index
> e540092d664d..06debeaec643 100644
> --- a/drivers/iommu/intel/dmar.c
> +++ b/drivers/iommu/intel/dmar.c
> @@ -2051,8 +2051,13 @@ int enable_drhd_fault_handling(unsigned int cpu)
>                  if (iommu->irq || iommu->node != cpu_to_node(cpu))
>                          continue;
> 
> +               /*
> +                * Call dmar_alloc_hwirq() with dmar_global_lock held,
> +                * could cause possible lock race condition.
> +                */
> +               up_read(&dmar_global_lock);
>                  ret = dmar_set_interrupt(iommu);
> -
> +               down_read(&dmar_global_lock);
>                  if (ret) {
>                          pr_err("DRHD %Lx: failed to enable fault, interrupt, ret %d\n",
>                                 (unsigned long long)drhd->reg_base_addr, ret);
> 
> Thanks,
> baolu

We still see the issue with this change.

Regards

Chaitanya

Re: Regression on drm-tip

[Baolu Lu]

On 3/14/25 17:04, Borah, Chaitanya Kumar wrote:
> 
> 
>> -----Original Message-----
>> From: Baolu Lu <baolu.lu@linux.intel.com>
>> Sent: Thursday, March 13, 2025 7:53 PM
>> To: Borah, Chaitanya Kumar <chaitanya.kumar.borah@intel.com>
>> Cc: baolu.lu@linux.intel.com; intel-gfx@lists.freedesktop.org; intel-
>> xe@lists.freedesktop.org; iommu@lists.linux.dev
>> Subject: Re: Regression on drm-tip
>>
>> On 2025/3/13 16:51, Borah, Chaitanya Kumar wrote:
>>> Hello Lu,
>>>
>>> Hope you are doing well. I am Chaitanya from the linux graphics team in
>> Intel.
>>>
>>> This mail is regarding a regression we are seeing in our CI runs[1] on drm-tip
>> repository.
>>>
>>> ``````````````````````````````````````````````````````````````````````
>>> ``````````` <4>[    2.856622] WARNING: possible circular locking
>>> dependency detected <4>[    2.856631]
>>> 6.14.0-rc5-CI_DRM_16217-gc55ef90b69d3+ #1 Tainted: G          I <4>[
>>> 2.856642] ------------------------------------------------------
>>> <4>[    2.856650] swapper/0/1 is trying to acquire lock:
>>> <4>[    2.856657] ffffffff8360ecc8
>>> (iommu_probe_device_lock){+.+.}-{3:3}, at:
>>> iommu_probe_device+0x1d/0x70 <4>[    2.856679]
>>>                     but task is already holding lock:
>>> <4>[    2.856686] ffff888102ab6fa8
>>> (&device->physical_node_lock){+.+.}-{3:3}, at:
>>> intel_iommu_init+0xea1/0x1220
>>> ``````````````````````````````````````````````````````````````````````
>>> ```````````
>>> Details log can be found in [2].
>>>
>>> After bisecting the tree, the following patch [3] seems to be the
>>> first "bad" commit
>>>
>>> ``````````````````````````````````````````````````````````````````````
>>> ```````````````````````````````````
>>> commit b150654f74bf0df8e6a7936d5ec51400d9ec06d8
>>> Author: Lu Baolumailto:baolu.lu@linux.intel.com
>>> Date:   Fri Feb 28 18:27:26 2025 +0800
>>>
>>>       iommu/vt-d: Fix suspicious RCU usage
>>>
>>> ``````````````````````````````````````````````````````````````````````
>>> ```````````````````````````````````
>>>
>>> We also verified that if we revert the patch the issue is not seen.
>>>
>>> Could you please check why the patch causes this regression and provide a
>> fix if necessary?
>>
>> Can you please take a quick test to check if the following fix works?
>>
>> diff --git a/drivers/iommu/intel/dmar.c b/drivers/iommu/intel/dmar.c index
>> e540092d664d..06debeaec643 100644
>> --- a/drivers/iommu/intel/dmar.c
>> +++ b/drivers/iommu/intel/dmar.c
>> @@ -2051,8 +2051,13 @@ int enable_drhd_fault_handling(unsigned int cpu)
>>                   if (iommu->irq || iommu->node != cpu_to_node(cpu))
>>                           continue;
>>
>> +               /*
>> +                * Call dmar_alloc_hwirq() with dmar_global_lock held,
>> +                * could cause possible lock race condition.
>> +                */
>> +               up_read(&dmar_global_lock);
>>                   ret = dmar_set_interrupt(iommu);
>> -
>> +               down_read(&dmar_global_lock);
>>                   if (ret) {
>>                           pr_err("DRHD %Lx: failed to enable fault, interrupt, ret %d\n",
>>                                  (unsigned long long)drhd->reg_base_addr, ret);
>>
>> Thanks,
>> baolu
> 
> We still see the issue with this change.

I am attempting to reproduce this issue with my MTL machine. I pulled
the test branch from:

https://anongit.freedesktop.org/git/drm-tip.git

and built the test kernel image using the configuration file from:

https://intel-gfx-ci.01.org/tree/drm-tip/CI_DRM_16217/kconfig.txt

But I did not observe the lockdep splat mentioned above after booting.

Is there anything I might have missed?

Thanks,
baolu

RE: Regression on drm-tip

[Borah, Chaitanya Kumar]

> -----Original Message-----
> From: Baolu Lu <baolu.lu@linux.intel.com>
> Sent: Sunday, March 16, 2025 8:04 AM
> To: Borah, Chaitanya Kumar <chaitanya.kumar.borah@intel.com>
> Cc: intel-gfx@lists.freedesktop.org; intel-xe@lists.freedesktop.org;
> iommu@lists.linux.dev
> Subject: Re: Regression on drm-tip
> 
> On 3/14/25 17:04, Borah, Chaitanya Kumar wrote:
> >
> >
> >> -----Original Message-----
> >> From: Baolu Lu <baolu.lu@linux.intel.com>
> >> Sent: Thursday, March 13, 2025 7:53 PM
> >> To: Borah, Chaitanya Kumar <chaitanya.kumar.borah@intel.com>
> >> Cc: baolu.lu@linux.intel.com; intel-gfx@lists.freedesktop.org; intel-
> >> xe@lists.freedesktop.org; iommu@lists.linux.dev
> >> Subject: Re: Regression on drm-tip
> >>
> >> On 2025/3/13 16:51, Borah, Chaitanya Kumar wrote:
> >>> Hello Lu,
> >>>
> >>> Hope you are doing well. I am Chaitanya from the linux graphics team
> >>> in
> >> Intel.
> >>>
> >>> This mail is regarding a regression we are seeing in our CI runs[1]
> >>> on drm-tip
> >> repository.
> >>>
> >>> ````````````````````````````````````````````````````````````````````
> >>> `` ``````````` <4>[    2.856622] WARNING: possible circular locking
> >>> dependency detected <4>[    2.856631]
> >>> 6.14.0-rc5-CI_DRM_16217-gc55ef90b69d3+ #1 Tainted: G          I <4>[
> >>> 2.856642] ------------------------------------------------------
> >>> <4>[    2.856650] swapper/0/1 is trying to acquire lock:
> >>> <4>[    2.856657] ffffffff8360ecc8
> >>> (iommu_probe_device_lock){+.+.}-{3:3}, at:
> >>> iommu_probe_device+0x1d/0x70 <4>[    2.856679]
> >>>                     but task is already holding lock:
> >>> <4>[    2.856686] ffff888102ab6fa8
> >>> (&device->physical_node_lock){+.+.}-{3:3}, at:
> >>> intel_iommu_init+0xea1/0x1220
> >>> ````````````````````````````````````````````````````````````````````
> >>> ``
> >>> ```````````
> >>> Details log can be found in [2].
> >>>
> >>> After bisecting the tree, the following patch [3] seems to be the
> >>> first "bad" commit
> >>>
> >>> ````````````````````````````````````````````````````````````````````
> >>> ``
> >>> ```````````````````````````````````
> >>> commit b150654f74bf0df8e6a7936d5ec51400d9ec06d8
> >>> Author: Lu Baolumailto:baolu.lu@linux.intel.com
> >>> Date:   Fri Feb 28 18:27:26 2025 +0800
> >>>
> >>>       iommu/vt-d: Fix suspicious RCU usage
> >>>
> >>> ````````````````````````````````````````````````````````````````````
> >>> ``
> >>> ```````````````````````````````````
> >>>
> >>> We also verified that if we revert the patch the issue is not seen.
> >>>
> >>> Could you please check why the patch causes this regression and
> >>> provide a
> >> fix if necessary?
> >>
> >> Can you please take a quick test to check if the following fix works?
> >>
> >> diff --git a/drivers/iommu/intel/dmar.c b/drivers/iommu/intel/dmar.c
> >> index
> >> e540092d664d..06debeaec643 100644
> >> --- a/drivers/iommu/intel/dmar.c
> >> +++ b/drivers/iommu/intel/dmar.c
> >> @@ -2051,8 +2051,13 @@ int enable_drhd_fault_handling(unsigned int
> cpu)
> >>                   if (iommu->irq || iommu->node != cpu_to_node(cpu))
> >>                           continue;
> >>
> >> +               /*
> >> +                * Call dmar_alloc_hwirq() with dmar_global_lock held,
> >> +                * could cause possible lock race condition.
> >> +                */
> >> +               up_read(&dmar_global_lock);
> >>                   ret = dmar_set_interrupt(iommu);
> >> -
> >> +               down_read(&dmar_global_lock);
> >>                   if (ret) {
> >>                           pr_err("DRHD %Lx: failed to enable fault, interrupt, ret
> %d\n",
> >>                                  (unsigned long
> >> long)drhd->reg_base_addr, ret);
> >>
> >> Thanks,
> >> baolu
> >
> > We still see the issue with this change.
> 
> I am attempting to reproduce this issue with my MTL machine. I pulled the
> test branch from:
> 
> https://anongit.freedesktop.org/git/drm-tip.git
> 
> and built the test kernel image using the configuration file from:
> 
> https://intel-gfx-ci.01.org/tree/drm-tip/CI_DRM_16217/kconfig.txt
> 
> But I did not observe the lockdep splat mentioned above after booting.
> 
> Is there anything I might have missed?
> 

+Suresh, Jani, Lucas

We are seeing this only the skykale and kabylake on our CI runs.

https://intel-gfx-ci.01.org/tree/drm-tip/igt@runner@aborted.html

Regards

Chaitanya

> Thanks,
> baolu

Re: Regression on drm-tip

[Baolu Lu]

On 3/16/25 15:27, Borah, Chaitanya Kumar wrote:
> 
>> -----Original Message-----
>> From: Baolu Lu<baolu.lu@linux.intel.com>
>> Sent: Sunday, March 16, 2025 8:04 AM
>> To: Borah, Chaitanya Kumar<chaitanya.kumar.borah@intel.com>
>> Cc:intel-gfx@lists.freedesktop.org;intel-xe@lists.freedesktop.org;
>> iommu@lists.linux.dev
>> Subject: Re: Regression on drm-tip
>>
>> On 3/14/25 17:04, Borah, Chaitanya Kumar wrote:
>>>
>>>> -----Original Message-----
>>>> From: Baolu Lu<baolu.lu@linux.intel.com>
>>>> Sent: Thursday, March 13, 2025 7:53 PM
>>>> To: Borah, Chaitanya Kumar<chaitanya.kumar.borah@intel.com>
>>>> Cc:baolu.lu@linux.intel.com;intel-gfx@lists.freedesktop.org; intel-
>>>> xe@lists.freedesktop.org;iommu@lists.linux.dev
>>>> Subject: Re: Regression on drm-tip
>>>>
>>>> On 2025/3/13 16:51, Borah, Chaitanya Kumar wrote:
>>>>> Hello Lu,
>>>>>
>>>>> Hope you are doing well. I am Chaitanya from the linux graphics team
>>>>> in
>>>> Intel.
>>>>> This mail is regarding a regression we are seeing in our CI runs[1]
>>>>> on drm-tip
>>>> repository.
>>>>> ````````````````````````````````````````````````````````````````````
>>>>> `` ``````````` <4>[    2.856622] WARNING: possible circular locking
>>>>> dependency detected <4>[    2.856631]
>>>>> 6.14.0-rc5-CI_DRM_16217-gc55ef90b69d3+ #1 Tainted: G          I <4>[
>>>>> 2.856642] ------------------------------------------------------
>>>>> <4>[    2.856650] swapper/0/1 is trying to acquire lock:
>>>>> <4>[    2.856657] ffffffff8360ecc8
>>>>> (iommu_probe_device_lock){+.+.}-{3:3}, at:
>>>>> iommu_probe_device+0x1d/0x70 <4>[    2.856679]
>>>>>                      but task is already holding lock:
>>>>> <4>[    2.856686] ffff888102ab6fa8
>>>>> (&device->physical_node_lock){+.+.}-{3:3}, at:
>>>>> intel_iommu_init+0xea1/0x1220
>>>>> ````````````````````````````````````````````````````````````````````
>>>>> ``
>>>>> ```````````
>>>>> Details log can be found in [2].
>>>>>
>>>>> After bisecting the tree, the following patch [3] seems to be the
>>>>> first "bad" commit
>>>>>
>>>>> ````````````````````````````````````````````````````````````````````
>>>>> ``
>>>>> ```````````````````````````````````
>>>>> commit b150654f74bf0df8e6a7936d5ec51400d9ec06d8
>>>>> Author: LuBaolumailto:baolu.lu@linux.intel.com
>>>>> Date:   Fri Feb 28 18:27:26 2025 +0800
>>>>>
>>>>>        iommu/vt-d: Fix suspicious RCU usage
>>>>>
>>>>> ````````````````````````````````````````````````````````````````````
>>>>> ``
>>>>> ```````````````````````````````````
>>>>>
>>>>> We also verified that if we revert the patch the issue is not seen.
>>>>>
>>>>> Could you please check why the patch causes this regression and
>>>>> provide a
>>>> fix if necessary?
>>>>
>>>> Can you please take a quick test to check if the following fix works?
>>>>
>>>> diff --git a/drivers/iommu/intel/dmar.c b/drivers/iommu/intel/dmar.c
>>>> index
>>>> e540092d664d..06debeaec643 100644
>>>> --- a/drivers/iommu/intel/dmar.c
>>>> +++ b/drivers/iommu/intel/dmar.c
>>>> @@ -2051,8 +2051,13 @@ int enable_drhd_fault_handling(unsigned int
>> cpu)
>>>>                    if (iommu->irq || iommu->node != cpu_to_node(cpu))
>>>>                            continue;
>>>>
>>>> +               /*
>>>> +                * Call dmar_alloc_hwirq() with dmar_global_lock held,
>>>> +                * could cause possible lock race condition.
>>>> +                */
>>>> +               up_read(&dmar_global_lock);
>>>>                    ret = dmar_set_interrupt(iommu);
>>>> -
>>>> +               down_read(&dmar_global_lock);
>>>>                    if (ret) {
>>>>                            pr_err("DRHD %Lx: failed to enable fault, interrupt, ret
>> %d\n",
>>>>                                   (unsigned long
>>>> long)drhd->reg_base_addr, ret);
>>>>
>>>> Thanks,
>>>> baolu
>>> We still see the issue with this change.
>> I am attempting to reproduce this issue with my MTL machine. I pulled the
>> test branch from:
>>
>> https://anongit.freedesktop.org/git/drm-tip.git
>>
>> and built the test kernel image using the configuration file from:
>>
>> https://intel-gfx-ci.01.org/tree/drm-tip/CI_DRM_16217/kconfig.txt
>>
>> But I did not observe the lockdep splat mentioned above after booting.
>>
>> Is there anything I might have missed?
>>
> +Suresh, Jani, Lucas
> 
> We are seeing this only the skykale and kabylake on our CI runs.

If so, will below change make any difference?

diff --git a/drivers/iommu/intel/iommu.c b/drivers/iommu/intel/iommu.c
index 85aa66ef4d61..ec2f385ae25b 100644
--- a/drivers/iommu/intel/iommu.c
+++ b/drivers/iommu/intel/iommu.c
@@ -3049,6 +3049,7 @@ static int __init probe_acpi_namespace_devices(void)
                         if (dev->bus != &acpi_bus_type)
                                 continue;

+                       up_read(&dmar_global_lock);
                         adev = to_acpi_device(dev);
                         mutex_lock(&adev->physical_node_lock);
                         list_for_each_entry(pn,
@@ -3058,6 +3059,7 @@ static int __init probe_acpi_namespace_devices(void)
                                         break;
                         }
                         mutex_unlock(&adev->physical_node_lock);
+                       down_read(&dmar_global_lock);

                         if (ret)
                                 return ret;

Thanks,
baolu

RE: Regression on drm-tip

[Borah, Chaitanya Kumar]

> -----Original Message-----
> From: Baolu Lu <baolu.lu@linux.intel.com>
> Sent: Sunday, March 16, 2025 1:33 PM
> To: Borah, Chaitanya Kumar <chaitanya.kumar.borah@intel.com>
> Cc: intel-gfx@lists.freedesktop.org; intel-xe@lists.freedesktop.org;
> iommu@lists.linux.dev; Kurmi, Suresh Kumar
> <suresh.kumar.kurmi@intel.com>; Saarinen, Jani <jani.saarinen@intel.com>;
> De Marchi, Lucas <lucas.demarchi@intel.com>
> Subject: Re: Regression on drm-tip
> 
> On 3/16/25 15:27, Borah, Chaitanya Kumar wrote:
> >
> >> -----Original Message-----
> >> From: Baolu Lu<baolu.lu@linux.intel.com>
> >> Sent: Sunday, March 16, 2025 8:04 AM
> >> To: Borah, Chaitanya Kumar<chaitanya.kumar.borah@intel.com>
> >> Cc:intel-gfx@lists.freedesktop.org;intel-xe@lists.freedesktop.org;
> >> iommu@lists.linux.dev
> >> Subject: Re: Regression on drm-tip
> >>
> >> On 3/14/25 17:04, Borah, Chaitanya Kumar wrote:
> >>>
> >>>> -----Original Message-----
> >>>> From: Baolu Lu<baolu.lu@linux.intel.com>
> >>>> Sent: Thursday, March 13, 2025 7:53 PM
> >>>> To: Borah, Chaitanya Kumar<chaitanya.kumar.borah@intel.com>
> >>>> Cc:baolu.lu@linux.intel.com;intel-gfx@lists.freedesktop.org; intel-
> >>>> xe@lists.freedesktop.org;iommu@lists.linux.dev
> >>>> Subject: Re: Regression on drm-tip
> >>>>
> >>>> On 2025/3/13 16:51, Borah, Chaitanya Kumar wrote:
> >>>>> Hello Lu,
> >>>>>
> >>>>> Hope you are doing well. I am Chaitanya from the linux graphics
> >>>>> team in
> >>>> Intel.
> >>>>> This mail is regarding a regression we are seeing in our CI
> >>>>> runs[1] on drm-tip
> >>>> repository.
> >>>>> ``````````````````````````````````````````````````````````````````
> >>>>> `` `` ``````````` <4>[    2.856622] WARNING: possible circular
> >>>>> locking dependency detected <4>[    2.856631]
> >>>>> 6.14.0-rc5-CI_DRM_16217-gc55ef90b69d3+ #1 Tainted: G          I
> >>>>> <4>[ 2.856642]
> >>>>> ------------------------------------------------------
> >>>>> <4>[    2.856650] swapper/0/1 is trying to acquire lock:
> >>>>> <4>[    2.856657] ffffffff8360ecc8
> >>>>> (iommu_probe_device_lock){+.+.}-{3:3}, at:
> >>>>> iommu_probe_device+0x1d/0x70 <4>[    2.856679]
> >>>>>                      but task is already holding lock:
> >>>>> <4>[    2.856686] ffff888102ab6fa8
> >>>>> (&device->physical_node_lock){+.+.}-{3:3}, at:
> >>>>> intel_iommu_init+0xea1/0x1220
> >>>>> ``````````````````````````````````````````````````````````````````
> >>>>> ``
> >>>>> ``
> >>>>> ```````````
> >>>>> Details log can be found in [2].
> >>>>>
> >>>>> After bisecting the tree, the following patch [3] seems to be the
> >>>>> first "bad" commit
> >>>>>
> >>>>> ``````````````````````````````````````````````````````````````````
> >>>>> ``
> >>>>> ``
> >>>>> ```````````````````````````````````
> >>>>> commit b150654f74bf0df8e6a7936d5ec51400d9ec06d8
> >>>>> Author: LuBaolumailto:baolu.lu@linux.intel.com
> >>>>> Date:   Fri Feb 28 18:27:26 2025 +0800
> >>>>>
> >>>>>        iommu/vt-d: Fix suspicious RCU usage
> >>>>>
> >>>>> ``````````````````````````````````````````````````````````````````
> >>>>> ``
> >>>>> ``
> >>>>> ```````````````````````````````````
> >>>>>
> >>>>> We also verified that if we revert the patch the issue is not seen.
> >>>>>
> >>>>> Could you please check why the patch causes this regression and
> >>>>> provide a
> >>>> fix if necessary?
> >>>>
> >>>> Can you please take a quick test to check if the following fix works?
> >>>>
> >>>> diff --git a/drivers/iommu/intel/dmar.c
> >>>> b/drivers/iommu/intel/dmar.c index
> >>>> e540092d664d..06debeaec643 100644
> >>>> --- a/drivers/iommu/intel/dmar.c
> >>>> +++ b/drivers/iommu/intel/dmar.c
> >>>> @@ -2051,8 +2051,13 @@ int enable_drhd_fault_handling(unsigned int
> >> cpu)
> >>>>                    if (iommu->irq || iommu->node != cpu_to_node(cpu))
> >>>>                            continue;
> >>>>
> >>>> +               /*
> >>>> +                * Call dmar_alloc_hwirq() with dmar_global_lock held,
> >>>> +                * could cause possible lock race condition.
> >>>> +                */
> >>>> +               up_read(&dmar_global_lock);
> >>>>                    ret = dmar_set_interrupt(iommu);
> >>>> -
> >>>> +               down_read(&dmar_global_lock);
> >>>>                    if (ret) {
> >>>>                            pr_err("DRHD %Lx: failed to enable
> >>>> fault, interrupt, ret
> >> %d\n",
> >>>>                                   (unsigned long
> >>>> long)drhd->reg_base_addr, ret);
> >>>>
> >>>> Thanks,
> >>>> baolu
> >>> We still see the issue with this change.
> >> I am attempting to reproduce this issue with my MTL machine. I pulled
> >> the test branch from:
> >>
> >> https://anongit.freedesktop.org/git/drm-tip.git
> >>
> >> and built the test kernel image using the configuration file from:
> >>
> >> https://intel-gfx-ci.01.org/tree/drm-tip/CI_DRM_16217/kconfig.txt
> >>
> >> But I did not observe the lockdep splat mentioned above after booting.
> >>
> >> Is there anything I might have missed?
> >>
> > +Suresh, Jani, Lucas
> >
> > We are seeing this only the skykale and kabylake on our CI runs.
> 
> If so, will below change make any difference?
> 
> diff --git a/drivers/iommu/intel/iommu.c b/drivers/iommu/intel/iommu.c
> index 85aa66ef4d61..ec2f385ae25b 100644
> --- a/drivers/iommu/intel/iommu.c
> +++ b/drivers/iommu/intel/iommu.c
> @@ -3049,6 +3049,7 @@ static int __init
> probe_acpi_namespace_devices(void)
>                          if (dev->bus != &acpi_bus_type)
>                                  continue;
> 
> +                       up_read(&dmar_global_lock);
>                          adev = to_acpi_device(dev);
>                          mutex_lock(&adev->physical_node_lock);
>                          list_for_each_entry(pn, @@ -3058,6 +3059,7 @@ static int __init
> probe_acpi_namespace_devices(void)
>                                          break;
>                          }
>                          mutex_unlock(&adev->physical_node_lock);
> +                       down_read(&dmar_global_lock);
> 
>                          if (ret)
>                                  return ret;
> 

Thank you for the change. This seems to be working. Can we expect a fix patch soon?

Regards

Chaitanya

> Thanks,
> baolu

Re: Regression on drm-tip

[Baolu Lu]

On 3/16/25 18:01, Borah, Chaitanya Kumar wrote:
> 
>> -----Original Message-----
>> From: Baolu Lu<baolu.lu@linux.intel.com>
>> Sent: Sunday, March 16, 2025 1:33 PM
>> To: Borah, Chaitanya Kumar<chaitanya.kumar.borah@intel.com>
>> Cc:intel-gfx@lists.freedesktop.org;intel-xe@lists.freedesktop.org;
>> iommu@lists.linux.dev; Kurmi, Suresh Kumar
>> <suresh.kumar.kurmi@intel.com>; Saarinen, Jani<jani.saarinen@intel.com>;
>> De Marchi, Lucas<lucas.demarchi@intel.com>
>> Subject: Re: Regression on drm-tip
>>
>> On 3/16/25 15:27, Borah, Chaitanya Kumar wrote:
>>>> -----Original Message-----
>>>> From: Baolu Lu<baolu.lu@linux.intel.com>
>>>> Sent: Sunday, March 16, 2025 8:04 AM
>>>> To: Borah, Chaitanya Kumar<chaitanya.kumar.borah@intel.com>
>>>> Cc:intel-gfx@lists.freedesktop.org;intel-xe@lists.freedesktop.org;
>>>> iommu@lists.linux.dev
>>>> Subject: Re: Regression on drm-tip
>>>>
>>>> On 3/14/25 17:04, Borah, Chaitanya Kumar wrote:
>>>>>> -----Original Message-----
>>>>>> From: Baolu Lu<baolu.lu@linux.intel.com>
>>>>>> Sent: Thursday, March 13, 2025 7:53 PM
>>>>>> To: Borah, Chaitanya Kumar<chaitanya.kumar.borah@intel.com>
>>>>>> Cc:baolu.lu@linux.intel.com;intel-gfx@lists.freedesktop.org; intel-
>>>>>> xe@lists.freedesktop.org;iommu@lists.linux.dev
>>>>>> Subject: Re: Regression on drm-tip
>>>>>>
>>>>>> On 2025/3/13 16:51, Borah, Chaitanya Kumar wrote:
>>>>>>> Hello Lu,
>>>>>>>
>>>>>>> Hope you are doing well. I am Chaitanya from the linux graphics
>>>>>>> team in
>>>>>> Intel.
>>>>>>> This mail is regarding a regression we are seeing in our CI
>>>>>>> runs[1] on drm-tip
>>>>>> repository.
>>>>>>> ``````````````````````````````````````````````````````````````````
>>>>>>> `` `` ``````````` <4>[    2.856622] WARNING: possible circular
>>>>>>> locking dependency detected <4>[    2.856631]
>>>>>>> 6.14.0-rc5-CI_DRM_16217-gc55ef90b69d3+ #1 Tainted: G          I
>>>>>>> <4>[ 2.856642]
>>>>>>> ------------------------------------------------------
>>>>>>> <4>[    2.856650] swapper/0/1 is trying to acquire lock:
>>>>>>> <4>[    2.856657] ffffffff8360ecc8
>>>>>>> (iommu_probe_device_lock){+.+.}-{3:3}, at:
>>>>>>> iommu_probe_device+0x1d/0x70 <4>[    2.856679]
>>>>>>>                       but task is already holding lock:
>>>>>>> <4>[    2.856686] ffff888102ab6fa8
>>>>>>> (&device->physical_node_lock){+.+.}-{3:3}, at:
>>>>>>> intel_iommu_init+0xea1/0x1220
>>>>>>> ``````````````````````````````````````````````````````````````````
>>>>>>> ``
>>>>>>> ``
>>>>>>> ```````````
>>>>>>> Details log can be found in [2].
>>>>>>>
>>>>>>> After bisecting the tree, the following patch [3] seems to be the
>>>>>>> first "bad" commit
>>>>>>>
>>>>>>> ``````````````````````````````````````````````````````````````````
>>>>>>> ``
>>>>>>> ``
>>>>>>> ```````````````````````````````````
>>>>>>> commit b150654f74bf0df8e6a7936d5ec51400d9ec06d8
>>>>>>> Author:LuBaolumailto:baolu.lu@linux.intel.com
>>>>>>> Date:   Fri Feb 28 18:27:26 2025 +0800
>>>>>>>
>>>>>>>         iommu/vt-d: Fix suspicious RCU usage
>>>>>>>
>>>>>>> ``````````````````````````````````````````````````````````````````
>>>>>>> ``
>>>>>>> ``
>>>>>>> ```````````````````````````````````
>>>>>>>
>>>>>>> We also verified that if we revert the patch the issue is not seen.
>>>>>>>
>>>>>>> Could you please check why the patch causes this regression and
>>>>>>> provide a
>>>>>> fix if necessary?
>>>>>>
>>>>>> Can you please take a quick test to check if the following fix works?
>>>>>>
>>>>>> diff --git a/drivers/iommu/intel/dmar.c
>>>>>> b/drivers/iommu/intel/dmar.c index
>>>>>> e540092d664d..06debeaec643 100644
>>>>>> --- a/drivers/iommu/intel/dmar.c
>>>>>> +++ b/drivers/iommu/intel/dmar.c
>>>>>> @@ -2051,8 +2051,13 @@ int enable_drhd_fault_handling(unsigned int
>>>> cpu)
>>>>>>                     if (iommu->irq || iommu->node != cpu_to_node(cpu))
>>>>>>                             continue;
>>>>>>
>>>>>> +               /*
>>>>>> +                * Call dmar_alloc_hwirq() with dmar_global_lock held,
>>>>>> +                * could cause possible lock race condition.
>>>>>> +                */
>>>>>> +               up_read(&dmar_global_lock);
>>>>>>                     ret = dmar_set_interrupt(iommu);
>>>>>> -
>>>>>> +               down_read(&dmar_global_lock);
>>>>>>                     if (ret) {
>>>>>>                             pr_err("DRHD %Lx: failed to enable
>>>>>> fault, interrupt, ret
>>>> %d\n",
>>>>>>                                    (unsigned long
>>>>>> long)drhd->reg_base_addr, ret);
>>>>>>
>>>>>> Thanks,
>>>>>> baolu
>>>>> We still see the issue with this change.
>>>> I am attempting to reproduce this issue with my MTL machine. I pulled
>>>> the test branch from:
>>>>
>>>> https://anongit.freedesktop.org/git/drm-tip.git
>>>>
>>>> and built the test kernel image using the configuration file from:
>>>>
>>>> https://intel-gfx-ci.01.org/tree/drm-tip/CI_DRM_16217/kconfig.txt
>>>>
>>>> But I did not observe the lockdep splat mentioned above after booting.
>>>>
>>>> Is there anything I might have missed?
>>>>
>>> +Suresh, Jani, Lucas
>>>
>>> We are seeing this only the skykale and kabylake on our CI runs.
>> If so, will below change make any difference?
>>
>> diff --git a/drivers/iommu/intel/iommu.c b/drivers/iommu/intel/iommu.c
>> index 85aa66ef4d61..ec2f385ae25b 100644
>> --- a/drivers/iommu/intel/iommu.c
>> +++ b/drivers/iommu/intel/iommu.c
>> @@ -3049,6 +3049,7 @@ static int __init
>> probe_acpi_namespace_devices(void)
>>                           if (dev->bus != &acpi_bus_type)
>>                                   continue;
>>
>> +                       up_read(&dmar_global_lock);
>>                           adev = to_acpi_device(dev);
>>                           mutex_lock(&adev->physical_node_lock);
>>                           list_for_each_entry(pn, @@ -3058,6 +3059,7 @@ static int __init
>> probe_acpi_namespace_devices(void)
>>                                           break;
>>                           }
>>                           mutex_unlock(&adev->physical_node_lock);
>> +                       down_read(&dmar_global_lock);
>>
>>                           if (ret)
>>                                   return ret;
>>
> Thank you for the change. This seems to be working. Can we expect a fix patch soon?

Sure. I have posted a fix patch here,

https://lore.kernel.org/linux-iommu/20250317035714.1041549-1-baolu.lu@linux.intel.com/

Thanks,
baolu

Re: Regression on drm-tip

[Lucas De Marchi]

On Mon, Mar 17, 2025 at 12:04:40PM +0800, Baolu Lu wrote:
>On 3/16/25 18:01, Borah, Chaitanya Kumar wrote:
>>
>>>-----Original Message-----
>>>From: Baolu Lu<baolu.lu@linux.intel.com>
>>>Sent: Sunday, March 16, 2025 1:33 PM
>>>To: Borah, Chaitanya Kumar<chaitanya.kumar.borah@intel.com>
>>>Cc:intel-gfx@lists.freedesktop.org;intel-xe@lists.freedesktop.org;
>>>iommu@lists.linux.dev; Kurmi, Suresh Kumar
>>><suresh.kumar.kurmi@intel.com>; Saarinen, Jani<jani.saarinen@intel.com>;
>>>De Marchi, Lucas<lucas.demarchi@intel.com>
>>>Subject: Re: Regression on drm-tip
>>>
>>>On 3/16/25 15:27, Borah, Chaitanya Kumar wrote:
>>>>>-----Original Message-----
>>>>>From: Baolu Lu<baolu.lu@linux.intel.com>
>>>>>Sent: Sunday, March 16, 2025 8:04 AM
>>>>>To: Borah, Chaitanya Kumar<chaitanya.kumar.borah@intel.com>
>>>>>Cc:intel-gfx@lists.freedesktop.org;intel-xe@lists.freedesktop.org;
>>>>>iommu@lists.linux.dev
>>>>>Subject: Re: Regression on drm-tip
>>>>>
>>>>>On 3/14/25 17:04, Borah, Chaitanya Kumar wrote:
>>>>>>>-----Original Message-----
>>>>>>>From: Baolu Lu<baolu.lu@linux.intel.com>
>>>>>>>Sent: Thursday, March 13, 2025 7:53 PM
>>>>>>>To: Borah, Chaitanya Kumar<chaitanya.kumar.borah@intel.com>
>>>>>>>Cc:baolu.lu@linux.intel.com;intel-gfx@lists.freedesktop.org; intel-
>>>>>>>xe@lists.freedesktop.org;iommu@lists.linux.dev
>>>>>>>Subject: Re: Regression on drm-tip
>>>>>>>
>>>>>>>On 2025/3/13 16:51, Borah, Chaitanya Kumar wrote:
>>>>>>>>Hello Lu,
>>>>>>>>
>>>>>>>>Hope you are doing well. I am Chaitanya from the linux graphics
>>>>>>>>team in
>>>>>>>Intel.
>>>>>>>>This mail is regarding a regression we are seeing in our CI
>>>>>>>>runs[1] on drm-tip
>>>>>>>repository.
>>>>>>>>``````````````````````````````````````````````````````````````````
>>>>>>>>`` `` ``````````` <4>[    2.856622] WARNING: possible circular
>>>>>>>>locking dependency detected <4>[    2.856631]
>>>>>>>>6.14.0-rc5-CI_DRM_16217-gc55ef90b69d3+ #1 Tainted: G          I
>>>>>>>><4>[ 2.856642]
>>>>>>>>------------------------------------------------------
>>>>>>>><4>[    2.856650] swapper/0/1 is trying to acquire lock:
>>>>>>>><4>[    2.856657] ffffffff8360ecc8
>>>>>>>>(iommu_probe_device_lock){+.+.}-{3:3}, at:
>>>>>>>>iommu_probe_device+0x1d/0x70 <4>[    2.856679]
>>>>>>>>                      but task is already holding lock:
>>>>>>>><4>[    2.856686] ffff888102ab6fa8
>>>>>>>>(&device->physical_node_lock){+.+.}-{3:3}, at:
>>>>>>>>intel_iommu_init+0xea1/0x1220
>>>>>>>>``````````````````````````````````````````````````````````````````
>>>>>>>>``
>>>>>>>>``
>>>>>>>>```````````
>>>>>>>>Details log can be found in [2].
>>>>>>>>
>>>>>>>>After bisecting the tree, the following patch [3] seems to be the
>>>>>>>>first "bad" commit
>>>>>>>>
>>>>>>>>``````````````````````````````````````````````````````````````````
>>>>>>>>``
>>>>>>>>``
>>>>>>>>```````````````````````````````````
>>>>>>>>commit b150654f74bf0df8e6a7936d5ec51400d9ec06d8
>>>>>>>>Author:LuBaolumailto:baolu.lu@linux.intel.com
>>>>>>>>Date:   Fri Feb 28 18:27:26 2025 +0800
>>>>>>>>
>>>>>>>>        iommu/vt-d: Fix suspicious RCU usage
>>>>>>>>
>>>>>>>>``````````````````````````````````````````````````````````````````
>>>>>>>>``
>>>>>>>>``
>>>>>>>>```````````````````````````````````
>>>>>>>>
>>>>>>>>We also verified that if we revert the patch the issue is not seen.
>>>>>>>>
>>>>>>>>Could you please check why the patch causes this regression and
>>>>>>>>provide a
>>>>>>>fix if necessary?
>>>>>>>
>>>>>>>Can you please take a quick test to check if the following fix works?
>>>>>>>
>>>>>>>diff --git a/drivers/iommu/intel/dmar.c
>>>>>>>b/drivers/iommu/intel/dmar.c index
>>>>>>>e540092d664d..06debeaec643 100644
>>>>>>>--- a/drivers/iommu/intel/dmar.c
>>>>>>>+++ b/drivers/iommu/intel/dmar.c
>>>>>>>@@ -2051,8 +2051,13 @@ int enable_drhd_fault_handling(unsigned int
>>>>>cpu)
>>>>>>>                    if (iommu->irq || iommu->node != cpu_to_node(cpu))
>>>>>>>                            continue;
>>>>>>>
>>>>>>>+               /*
>>>>>>>+                * Call dmar_alloc_hwirq() with dmar_global_lock held,
>>>>>>>+                * could cause possible lock race condition.
>>>>>>>+                */
>>>>>>>+               up_read(&dmar_global_lock);
>>>>>>>                    ret = dmar_set_interrupt(iommu);
>>>>>>>-
>>>>>>>+               down_read(&dmar_global_lock);
>>>>>>>                    if (ret) {
>>>>>>>                            pr_err("DRHD %Lx: failed to enable
>>>>>>>fault, interrupt, ret
>>>>>%d\n",
>>>>>>>                                   (unsigned long
>>>>>>>long)drhd->reg_base_addr, ret);
>>>>>>>
>>>>>>>Thanks,
>>>>>>>baolu
>>>>>>We still see the issue with this change.
>>>>>I am attempting to reproduce this issue with my MTL machine. I pulled
>>>>>the test branch from:
>>>>>
>>>>>https://anongit.freedesktop.org/git/drm-tip.git
>>>>>
>>>>>and built the test kernel image using the configuration file from:
>>>>>
>>>>>https://intel-gfx-ci.01.org/tree/drm-tip/CI_DRM_16217/kconfig.txt
>>>>>
>>>>>But I did not observe the lockdep splat mentioned above after booting.
>>>>>
>>>>>Is there anything I might have missed?
>>>>>
>>>>+Suresh, Jani, Lucas
>>>>
>>>>We are seeing this only the skykale and kabylake on our CI runs.
>>>If so, will below change make any difference?
>>>
>>>diff --git a/drivers/iommu/intel/iommu.c b/drivers/iommu/intel/iommu.c
>>>index 85aa66ef4d61..ec2f385ae25b 100644
>>>--- a/drivers/iommu/intel/iommu.c
>>>+++ b/drivers/iommu/intel/iommu.c
>>>@@ -3049,6 +3049,7 @@ static int __init
>>>probe_acpi_namespace_devices(void)
>>>                          if (dev->bus != &acpi_bus_type)
>>>                                  continue;
>>>
>>>+                       up_read(&dmar_global_lock);
>>>                          adev = to_acpi_device(dev);
>>>                          mutex_lock(&adev->physical_node_lock);
>>>                          list_for_each_entry(pn, @@ -3058,6 +3059,7 @@ static int __init
>>>probe_acpi_namespace_devices(void)
>>>                                          break;
>>>                          }
>>>                          mutex_unlock(&adev->physical_node_lock);
>>>+                       down_read(&dmar_global_lock);
>>>
>>>                          if (ret)
>>>                                  return ret;
>>>
>>Thank you for the change. This seems to be working. Can we expect a fix patch soon?
>
>Sure. I have posted a fix patch here,
>
>https://lore.kernel.org/linux-iommu/20250317035714.1041549-1-baolu.lu@linux.intel.com/

Thanks. FWIW I added this patch to our test branch in CI and the issue
is indeed not reproducing anymore.

Lucas De Marchi