[PATCH] fix gpu/drm/nouveau: fix return type in nouveau_dmem_migrate_to_ram()

[PATCH] fix gpu/drm/nouveau: fix return type in nouveau_dmem_migrate_to_ram()

[Balbir Singh]

ret of type vm_fault_t is reused to capture the return value of
nouveau_dmem_copy_folio(), which returns an int. Use a new copy_ret
to fix the issue. The issue is not new, prior to this the function
called was called nouveau_dmem_copy_one() and ret was used to capture
it's value.

Reported-by: kernel test robot <lkp@intel.com>
Closes: https://lore.kernel.org/oe-kbuild-all/202511121922.oP20Lzb8-lkp@intel.com/

Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: David Hildenbrand <david@redhat.com>
Cc: Zi Yan <ziy@nvidia.com>
Cc: Joshua Hahn <joshua.hahnjy@gmail.com>
Cc: Rakie Kim <rakie.kim@sk.com>
Cc: Byungchul Park <byungchul@sk.com>
Cc: Gregory Price <gourry@gourry.net>
Cc: Ying Huang <ying.huang@linux.alibaba.com>
Cc: Alistair Popple <apopple@nvidia.com>
Cc: Oscar Salvador <osalvador@suse.de>
Cc: Lorenzo Stoakes <lorenzo.stoakes@oracle.com>
Cc: Baolin Wang <baolin.wang@linux.alibaba.com>
Cc: "Liam R. Howlett" <Liam.Howlett@oracle.com>
Cc: Nico Pache <npache@redhat.com>
Cc: Ryan Roberts <ryan.roberts@arm.com>
Cc: Dev Jain <dev.jain@arm.com>
Cc: Barry Song <baohua@kernel.org>
Cc: Lyude Paul <lyude@redhat.com>
Cc: Danilo Krummrich <dakr@kernel.org>
Cc: David Airlie <airlied@gmail.com>
Cc: Simona Vetter <simona@ffwll.ch>
Cc: Ralph Campbell <rcampbell@nvidia.com>
Cc: Mika Penttilä <mpenttil@redhat.com>
Cc: Matthew Brost <matthew.brost@intel.com>
Cc: Francois Dugast <francois.dugast@intel.com>

Signed-off-by: Balbir Singh <balbirs@nvidia.com>
---
 drivers/gpu/drm/nouveau/nouveau_dmem.c | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/drivers/gpu/drm/nouveau/nouveau_dmem.c b/drivers/gpu/drm/nouveau/nouveau_dmem.c
index 244812e7dd69..06f2c544c2cb 100644
--- a/drivers/gpu/drm/nouveau/nouveau_dmem.c
+++ b/drivers/gpu/drm/nouveau/nouveau_dmem.c
@@ -188,6 +188,7 @@ static vm_fault_t nouveau_dmem_migrate_to_ram(struct vm_fault *vmf)
 	struct nouveau_svmm *svmm;
 	struct page *dpage;
 	vm_fault_t ret = 0;
+	int copy_ret;
 	struct migrate_vma args = {
 		.vma		= vmf->vma,
 		.pgmap_owner	= drm->dev,
@@ -256,9 +257,9 @@ static vm_fault_t nouveau_dmem_migrate_to_ram(struct vm_fault *vmf)
 	svmm = folio_zone_device_data(sfolio);
 	mutex_lock(&svmm->mutex);
 	nouveau_svmm_invalidate(svmm, args.start, args.end);
-	ret = nouveau_dmem_copy_folio(drm, sfolio, dfolio, &dma_info);
+	copy_ret = nouveau_dmem_copy_folio(drm, sfolio, dfolio, &dma_info);
 	mutex_unlock(&svmm->mutex);
-	if (ret) {
+	if (copy_ret) {
 		ret = VM_FAULT_SIGBUS;
 		goto done;
 	}
-- 
2.51.1

Re: [PATCH] fix gpu/drm/nouveau: fix return type in nouveau_dmem_migrate_to_ram()

[David Hildenbrand (Red Hat)]

On 13.11.25 06:13, Balbir Singh wrote:
> ret of type vm_fault_t is reused to capture the return value of
> nouveau_dmem_copy_folio(), which returns an int. Use a new copy_ret
> to fix the issue. The issue is not new, prior to this the function
> called was called nouveau_dmem_copy_one() and ret was used to capture
> it's value.
> 
> Reported-by: kernel test robot <lkp@intel.com>
> Closes: https://lore.kernel.org/oe-kbuild-all/202511121922.oP20Lzb8-lkp@intel.com/

It's a sparse warning, is there any runtime effect?

> 
> Cc: Andrew Morton <akpm@linux-foundation.org>
> Cc: David Hildenbrand <david@redhat.com>
> Cc: Zi Yan <ziy@nvidia.com>
> Cc: Joshua Hahn <joshua.hahnjy@gmail.com>
> Cc: Rakie Kim <rakie.kim@sk.com>
> Cc: Byungchul Park <byungchul@sk.com>
> Cc: Gregory Price <gourry@gourry.net>
> Cc: Ying Huang <ying.huang@linux.alibaba.com>
> Cc: Alistair Popple <apopple@nvidia.com>
> Cc: Oscar Salvador <osalvador@suse.de>
> Cc: Lorenzo Stoakes <lorenzo.stoakes@oracle.com>
> Cc: Baolin Wang <baolin.wang@linux.alibaba.com>
> Cc: "Liam R. Howlett" <Liam.Howlett@oracle.com>
> Cc: Nico Pache <npache@redhat.com>
> Cc: Ryan Roberts <ryan.roberts@arm.com>
> Cc: Dev Jain <dev.jain@arm.com>
> Cc: Barry Song <baohua@kernel.org>
> Cc: Lyude Paul <lyude@redhat.com>
> Cc: Danilo Krummrich <dakr@kernel.org>
> Cc: David Airlie <airlied@gmail.com>
> Cc: Simona Vetter <simona@ffwll.ch>
> Cc: Ralph Campbell <rcampbell@nvidia.com>
> Cc: Mika Penttilä <mpenttil@redhat.com>
> Cc: Matthew Brost <matthew.brost@intel.com>
> Cc: Francois Dugast <francois.dugast@intel.com>
> 

Fixes: ? Or is does this just fix a sparse warning and nothing "real" we 
could run into and cause problems?


-- 
Cheers

David

Re: [PATCH] fix gpu/drm/nouveau: fix return type in nouveau_dmem_migrate_to_ram()

[Balbir Singh]

On 11/13/25 20:09, David Hildenbrand (Red Hat) wrote:
> On 13.11.25 06:13, Balbir Singh wrote:
>> ret of type vm_fault_t is reused to capture the return value of
>> nouveau_dmem_copy_folio(), which returns an int. Use a new copy_ret
>> to fix the issue. The issue is not new, prior to this the function
>> called was called nouveau_dmem_copy_one() and ret was used to capture
>> it's value.
>>
>> Reported-by: kernel test robot <lkp@intel.com>
>> Closes: https://lore.kernel.org/oe-kbuild-all/202511121922.oP20Lzb8-lkp@intel.com/
> 
> It's a sparse warning, is there any runtime effect?
> 

No impact really, it's just a sparse warning

>>
>> Cc: Andrew Morton <akpm@linux-foundation.org>
>> Cc: David Hildenbrand <david@redhat.com>
>> Cc: Zi Yan <ziy@nvidia.com>
>> Cc: Joshua Hahn <joshua.hahnjy@gmail.com>
>> Cc: Rakie Kim <rakie.kim@sk.com>
>> Cc: Byungchul Park <byungchul@sk.com>
>> Cc: Gregory Price <gourry@gourry.net>
>> Cc: Ying Huang <ying.huang@linux.alibaba.com>
>> Cc: Alistair Popple <apopple@nvidia.com>
>> Cc: Oscar Salvador <osalvador@suse.de>
>> Cc: Lorenzo Stoakes <lorenzo.stoakes@oracle.com>
>> Cc: Baolin Wang <baolin.wang@linux.alibaba.com>
>> Cc: "Liam R. Howlett" <Liam.Howlett@oracle.com>
>> Cc: Nico Pache <npache@redhat.com>
>> Cc: Ryan Roberts <ryan.roberts@arm.com>
>> Cc: Dev Jain <dev.jain@arm.com>
>> Cc: Barry Song <baohua@kernel.org>
>> Cc: Lyude Paul <lyude@redhat.com>
>> Cc: Danilo Krummrich <dakr@kernel.org>
>> Cc: David Airlie <airlied@gmail.com>
>> Cc: Simona Vetter <simona@ffwll.ch>
>> Cc: Ralph Campbell <rcampbell@nvidia.com>
>> Cc: Mika Penttilä <mpenttil@redhat.com>
>> Cc: Matthew Brost <matthew.brost@intel.com>
>> Cc: Francois Dugast <francois.dugast@intel.com>
>>
> 
> Fixes: ? Or is does this just fix a sparse warning and nothing "real" we could run into and cause problems?
> 
> 


There is no "real" impact, it's a warning about the type mismatch.
The return value is checked as a boolean. There is no need to backport
to stable, IMHO

Balbir

Re: [PATCH] fix gpu/drm/nouveau: fix return type in nouveau_dmem_migrate_to_ram()

[David Hildenbrand (Red Hat)]

On 13.11.25 11:31, Balbir Singh wrote:
> On 11/13/25 20:09, David Hildenbrand (Red Hat) wrote:
>> On 13.11.25 06:13, Balbir Singh wrote:
>>> ret of type vm_fault_t is reused to capture the return value of
>>> nouveau_dmem_copy_folio(), which returns an int. Use a new copy_ret
>>> to fix the issue. The issue is not new, prior to this the function
>>> called was called nouveau_dmem_copy_one() and ret was used to capture
>>> it's value.
>>>
>>> Reported-by: kernel test robot <lkp@intel.com>
>>> Closes: https://lore.kernel.org/oe-kbuild-all/202511121922.oP20Lzb8-lkp@intel.com/
>>
>> It's a sparse warning, is there any runtime effect?
>>
> 
> No impact really, it's just a sparse warning

Okay, then please

1) Make that clear in the patch description

2) Make that clear in the patch subject.

In particular, the current subject is weird. Should probably be

"nouveau/dmem: fix sparse warning in nouveau_dmem_migrate_to_ram()"

Change itself LGTM, although I would probably call it "int err" or 
something like that instead.

-- 
Cheers

David

Re: [PATCH] fix gpu/drm/nouveau: fix return type in nouveau_dmem_migrate_to_ram()

[Balbir Singh]

On 11/13/25 22:50, David Hildenbrand (Red Hat) wrote:
> On 13.11.25 11:31, Balbir Singh wrote:
>> On 11/13/25 20:09, David Hildenbrand (Red Hat) wrote:
>>> On 13.11.25 06:13, Balbir Singh wrote:
>>>> ret of type vm_fault_t is reused to capture the return value of
>>>> nouveau_dmem_copy_folio(), which returns an int. Use a new copy_ret
>>>> to fix the issue. The issue is not new, prior to this the function
>>>> called was called nouveau_dmem_copy_one() and ret was used to capture
>>>> it's value.
>>>>
>>>> Reported-by: kernel test robot <lkp@intel.com>
>>>> Closes: https://lore.kernel.org/oe-kbuild-all/202511121922.oP20Lzb8-lkp@intel.com/
>>>
>>> It's a sparse warning, is there any runtime effect?
>>>
>>
>> No impact really, it's just a sparse warning
> 
> Okay, then please
> 
> 1) Make that clear in the patch description
> 
> 2) Make that clear in the patch subject.
> 
> In particular, the current subject is weird. Should probably be
> 
> "nouveau/dmem: fix sparse warning in nouveau_dmem_migrate_to_ram()"
> 

I did have "sparse warning" in the subject and checkpatch complained that
tools should not be mentioned in the subject, but I'll give it a shot with that.

> Change itself LGTM, although I would probably call it "int err" or something like that instead.
> 

Ack, will do that and resend

Balbir

Re: [PATCH] fix gpu/drm/nouveau: fix return type in nouveau_dmem_migrate_to_ram()

[David Hildenbrand (Red Hat)]

On 13.11.25 21:51, Balbir Singh wrote:
> On 11/13/25 22:50, David Hildenbrand (Red Hat) wrote:
>> On 13.11.25 11:31, Balbir Singh wrote:
>>> On 11/13/25 20:09, David Hildenbrand (Red Hat) wrote:
>>>> On 13.11.25 06:13, Balbir Singh wrote:
>>>>> ret of type vm_fault_t is reused to capture the return value of
>>>>> nouveau_dmem_copy_folio(), which returns an int. Use a new copy_ret
>>>>> to fix the issue. The issue is not new, prior to this the function
>>>>> called was called nouveau_dmem_copy_one() and ret was used to capture
>>>>> it's value.
>>>>>
>>>>> Reported-by: kernel test robot <lkp@intel.com>
>>>>> Closes: https://lore.kernel.org/oe-kbuild-all/202511121922.oP20Lzb8-lkp@intel.com/
>>>>
>>>> It's a sparse warning, is there any runtime effect?
>>>>
>>>
>>> No impact really, it's just a sparse warning
>>
>> Okay, then please
>>
>> 1) Make that clear in the patch description
>>
>> 2) Make that clear in the patch subject.
>>
>> In particular, the current subject is weird. Should probably be
>>
>> "nouveau/dmem: fix sparse warning in nouveau_dmem_migrate_to_ram()"
>>
> 
> I did have "sparse warning" in the subject and checkpatch complained that
> tools should not be mentioned in the subject, but I'll give it a shot with that.

The important part is to be careful with the term "fix" when all we're 
fixing is some output of a static code analysis tool that does otherwise 
not result in any actual issues (build time, runtime).

-- 
Cheers

David