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charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit On 10/20/2025 12:45 PM, Kim, Jonathan wrote: > > [Public] > > > Why print something under conditions where it’s not needed then? > > Could this not be a pr_debug instead? > > The number of queues could be quite large. > > I don’t see the merit in potentially spamming dmesgs if driver is > going to clean up anyways. > I think the issue here is not about print this warning or not. The issue is queues associate with prange should have been destroyed before prange got unmapped. Regards Xiaogang > Jon > > *From:*Chen, Xiaogang > *Sent:* Monday, October 20, 2025 1:34 PM > *To:* Kim, Jonathan ; Yang, Philip > ; amd-gfx@lists.freedesktop.org > *Cc:* Kuehling, Felix > *Subject:* Re: [PATCH v3 1/2] drm/amdkfd: Fix false positive queue > buffer free warning > > On 10/20/2025 11:24 AM, Kim, Jonathan wrote: > > [Public] > > You can see this error message on CTRL-C or gpu reset conditions. > > Those don’t seem like application race conditions to me i.e. the > app can’t do anything about terminations it can’t see coming. > > It appears any bad actor could spam dmesgs with these error > messages if they wanted to with the way the driver currently is. > > If this warning message comes out due to some unexpected things > happened(like ctrl-c) I think user would not be surprised to see some > warnings. > > Regards > > Xiaogang > > Jon > > *From:*amd-gfx > *On Behalf Of > *Chen, Xiaogang > *Sent:* Monday, October 20, 2025 12:00 PM > *To:* Yang, Philip > ; amd-gfx@lists.freedesktop.org > *Cc:* Kuehling, Felix > > *Subject:* Re: [PATCH v3 1/2] drm/amdkfd: Fix false positive queue > buffer free warning > > > > > *Caution:*This message originated from an External Source. Use > proper caution when opening attachments, clicking links, or > responding. > > On 10/20/2025 9:30 AM, Philip Yang wrote: > > Only show warning message if process mm is still alive when queue > > buffer is freed. > > > > If kfd_lookup_process_by_mm return NULL, means the process is already > > exited and mm is gone, it is fine to free queue buffer. > > > > Fixes: b049504e211e ("drm/amdkfd: Validate user queue svm memory residency") > > Signed-off-by: Philip Yang > > --- > > drivers/gpu/drm/amd/amdkfd/kfd_svm.c | 5 +++-- > > 1 file changed, 3 insertions(+), 2 deletions(-) > > > > diff --git a/drivers/gpu/drm/amd/amdkfd/kfd_svm.c b/drivers/gpu/drm/amd/amdkfd/kfd_svm.c > > index 4d4a47313f5b..d1b2f8525f80 100644 > > --- a/drivers/gpu/drm/amd/amdkfd/kfd_svm.c > > +++ b/drivers/gpu/drm/amd/amdkfd/kfd_svm.c > > @@ -2487,7 +2487,9 @@ svm_range_unmap_from_cpu(struct mm_struct *mm, struct svm_range *prange, > >         bool unmap_parent; > >         uint32_t i; > > > > -        if (atomic_read(&prange->queue_refcount)) { > > +        p = kfd_lookup_process_by_mm(mm); > > p->mm is null, not p  because driver set p->mm to null. But > still prange->queue_refcount is ref of queues from this prange. If > app unmap this prange app should have destroyed the queues > associated with this prange already. If not, it is not driver > issue. I think driver should send this warning anyway to indicate > there are queues not destroyed by app before app unmap the prange. > It is an app race condition, not driver. > > Regards > > Xiaogang > > > > + > > +        if (p && atomic_read(&prange->queue_refcount)) { > >                int r; > > > >                 pr_warn("Freeing queue vital buffer 0x%lx, queue evicted\n", > > @@ -2497,7 +2499,6 @@ svm_range_unmap_from_cpu(struct mm_struct *mm, struct svm_range *prange, > >                        pr_debug("failed %d to quiesce KFD queues\n", r); > >         } > > > > -        p = kfd_lookup_process_by_mm(mm); > >         if (!p) > >                return; > >         svms = &p->svms; > --------------AAYhv5QIXk3ZnC1Mwgp72Wp8 Content-Type: text/html; charset=UTF-8 Content-Transfer-Encoding: 8bit


On 10/20/2025 12:45 PM, Kim, Jonathan wrote:

[Public]


Why print something under conditions where it’s not needed then?

Could this not be a pr_debug instead?

The number of queues could be quite large.

I don’t see the merit in potentially spamming dmesgs if driver is going to clean up anyways.

I think the issue here is not about print this warning or not. The issue is queues associate with prange should have been destroyed before prange got unmapped.

Regards

Xiaogang

 

Jon

 

From: Chen, Xiaogang <Xiaogang.Chen@amd.com>
Sent: Monday, October 20, 2025 1:34 PM
To: Kim, Jonathan <Jonathan.Kim@amd.com>; Yang, Philip <Philip.Yang@amd.com>; amd-gfx@lists.freedesktop.org
Cc: Kuehling, Felix <Felix.Kuehling@amd.com>
Subject: Re: [PATCH v3 1/2] drm/amdkfd: Fix false positive queue buffer free warning

 

 

On 10/20/2025 11:24 AM, Kim, Jonathan wrote:

[Public]

 

You can see this error message on CTRL-C or gpu reset conditions.

Those don’t seem like application race conditions to me i.e. the app can’t do anything about terminations it can’t see coming.

It appears any bad actor could spam dmesgs with these error messages if they wanted to with the way the driver currently is.

If this warning message comes out due to some unexpected things happened(like ctrl-c) I think user would not be surprised to see some warnings.

Regards

Xiaogang

 

Jon

 

 

From: amd-gfx <amd-gfx-bounces@lists.freedesktop.org> On Behalf Of Chen, Xiaogang
Sent: Monday, October 20, 2025 12:00 PM
To: Yang, Philip <Philip.Yang@amd.com>; amd-gfx@lists.freedesktop.org
Cc: Kuehling, Felix <Felix.Kuehling@amd.com>
Subject: Re: [PATCH v3 1/2] drm/amdkfd: Fix false positive queue buffer free warning

 

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On 10/20/2025 9:30 AM, Philip Yang wrote:

Only show warning message if process mm is still alive when queue
buffer is freed.
 
If kfd_lookup_process_by_mm return NULL, means the process is already
exited and mm is gone, it is fine to free queue buffer.
 
Fixes: b049504e211e ("drm/amdkfd: Validate user queue svm memory residency")
Signed-off-by: Philip Yang <Philip.Yang@amd.com>
---
 drivers/gpu/drm/amd/amdkfd/kfd_svm.c | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)
 
diff --git a/drivers/gpu/drm/amd/amdkfd/kfd_svm.c b/drivers/gpu/drm/amd/amdkfd/kfd_svm.c
index 4d4a47313f5b..d1b2f8525f80 100644
--- a/drivers/gpu/drm/amd/amdkfd/kfd_svm.c
+++ b/drivers/gpu/drm/amd/amdkfd/kfd_svm.c
@@ -2487,7 +2487,9 @@ svm_range_unmap_from_cpu(struct mm_struct *mm, struct svm_range *prange,
         bool unmap_parent;
         uint32_t i;
 
-        if (atomic_read(&prange->queue_refcount)) {
+        p = kfd_lookup_process_by_mm(mm);

p->mm is null, not p  because driver set p->mm to null. But still prange->queue_refcount is ref of queues from this prange. If app unmap this prange app should have destroyed the queues associated with this prange already. If not, it is not driver issue. I think driver should send this warning anyway to indicate there are queues not destroyed by app before app unmap the prange. It is an app race condition, not driver.

Regards

Xiaogang

 
+
+        if (p && atomic_read(&prange->queue_refcount)) {
                int r;
 
                pr_warn("Freeing queue vital buffer 0x%lx, queue evicted\n",
@@ -2497,7 +2499,6 @@ svm_range_unmap_from_cpu(struct mm_struct *mm, struct svm_range *prange,
                        pr_debug("failed %d to quiesce KFD queues\n", r);
         }
 
-        p = kfd_lookup_process_by_mm(mm);
         if (!p)
                return;
         svms = &p->svms;
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