Jon
*From:*Chen, Xiaogang <[email protected]>
*Sent:* Monday, October 20, 2025 1:34 PM
*To:* Kim, Jonathan <[email protected]>; Yang, Philip
<[email protected]>; [email protected]
*Cc:* Kuehling, Felix <[email protected]>
*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 <[email protected]>
<mailto:[email protected]> *On Behalf Of
*Chen, Xiaogang
*Sent:* Monday, October 20, 2025 12:00 PM
*To:* Yang, Philip <[email protected]>
<mailto:[email protected]>; [email protected]
*Cc:* Kuehling, Felix <[email protected]>
<mailto:[email protected]>
*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<[email protected]>
<mailto:[email protected]>
---
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;
