On 5/26/26 09:54, Zhu, Lingshan wrote:
> On 5/26/2026 3:02 AM, Christian König wrote:
>
>> On 5/25/26 10:23, Zhu Lingshan wrote:
>>> MES process context is a process-level page
>>> where process specific context is saved for
>>> MES scheduler.
>>>
>>> However, current user-queue code path assigns
>>> fw_obj of a queue to MES process_context_addr
>>> when adding the queue to MES.
>>>
>>> This means every new queue from the same process
>>> would replace the previous process context address
>>> with that queue's fw_obj address.
>>> What's worse is, when user space frees a queue,
>>> its fw_obj will be freed as well, causing MES
>>> working on a NULL page pointer.
>>>
>>> This issue leads to inconsistency and crash
>>> in the scheduler.
>>>
>>> This commit allocates a process-level page for
>>> MES process contexts for a process other than queue-level
>>>
>>> Signed-off-by: Zhu Lingshan <[email protected]>
>>> ---
>>> drivers/gpu/drm/amd/amdgpu/amdgpu_userq.c | 5 +++
>>> drivers/gpu/drm/amd/amdgpu/amdgpu_userq.h | 1 +
>>> drivers/gpu/drm/amd/amdgpu/mes_userqueue.c | 48 ++++++++++++++++------
>>> 3 files changed, 42 insertions(+), 12 deletions(-)
>>>
>>> diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_userq.c
>>> b/drivers/gpu/drm/amd/amdgpu/amdgpu_userq.c
>>> index 38e310a8694d..0c4d6f80616e 100644
>>> --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_userq.c
>>> +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_userq.c
>>> @@ -1225,6 +1225,11 @@ void amdgpu_userq_mgr_fini(struct amdgpu_userq_mgr
>>> *userq_mgr)
>>> */
>>> cancel_work_sync(&userq_mgr->reset_work);
>>>
>>> + if (userq_mgr->proc_ctx_obj.obj)
>> Please drop that check it is unecessary.
>
> sure, I can drop this in V2.
>
>>> + amdgpu_bo_free_kernel(&userq_mgr->proc_ctx_obj.obj,
>>> + &userq_mgr->proc_ctx_obj.gpu_addr,
>>> + &userq_mgr->proc_ctx_obj.cpu_ptr);
>>> +
>>> mutex_destroy(&userq_mgr->userq_mutex);
>>> }
>>>
>>> diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_userq.h
>>> b/drivers/gpu/drm/amd/amdgpu/amdgpu_userq.h
>>> index 28cfc6682333..fe85234e58b3 100644
>>> --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_userq.h
>>> +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_userq.h
>>> @@ -127,6 +127,7 @@ struct amdgpu_userq_mgr {
>>> struct amdgpu_device *adev;
>>> struct delayed_work resume_work;
>>> struct drm_file *file;
>>> + struct amdgpu_userq_obj proc_ctx_obj;
>>>
>>> /**
>>> * @reset_work:
>>> diff --git a/drivers/gpu/drm/amd/amdgpu/mes_userqueue.c
>>> b/drivers/gpu/drm/amd/amdgpu/mes_userqueue.c
>>> index e9189f07c6dc..3022025bc2ec 100644
>>> --- a/drivers/gpu/drm/amd/amdgpu/mes_userqueue.c
>>> +++ b/drivers/gpu/drm/amd/amdgpu/mes_userqueue.c
>>> @@ -133,8 +133,8 @@ static int mes_userq_map(struct amdgpu_usermode_queue
>>> *queue)
>>> queue_input.gang_quantum = 10000;
>>> queue_input.paging = false;
>>>
>>> - queue_input.process_context_addr = ctx->gpu_addr;
>>> - queue_input.gang_context_addr = ctx->gpu_addr +
>>> AMDGPU_USERQ_PROC_CTX_SZ;
>>> + queue_input.process_context_addr = uq_mgr->proc_ctx_obj.gpu_addr;
>>> + queue_input.gang_context_addr = ctx->gpu_addr;
>>> queue_input.inprocess_gang_priority = AMDGPU_MES_PRIORITY_LEVEL_NORMAL;
>>> queue_input.gang_global_priority_level =
>>> convert_to_mes_priority(queue->priority);
>>>
>>> @@ -169,7 +169,7 @@ static int mes_userq_unmap(struct amdgpu_usermode_queue
>>> *queue)
>>>
>>> memset(&queue_input, 0x0, sizeof(struct mes_remove_queue_input));
>>> queue_input.doorbell_offset = queue->doorbell_index;
>>> - queue_input.gang_context_addr = ctx->gpu_addr +
>>> AMDGPU_USERQ_PROC_CTX_SZ;
>>> + queue_input.gang_context_addr = ctx->gpu_addr;
>>>
>>> amdgpu_mes_lock(&adev->mes);
>>> r = adev->mes.funcs->remove_hw_queue(&adev->mes, &queue_input);
>>> @@ -186,12 +186,8 @@ static int mes_userq_create_ctx_space(struct
>>> amdgpu_userq_mgr *uq_mgr,
>>> struct amdgpu_userq_obj *ctx = &queue->fw_obj;
>>> int r, size;
>>>
>>> - /*
>>> - * The FW expects at least one page space allocated for
>>> - * process ctx and gang ctx each. Create an object
>>> - * for the same.
>>> - */
>>> - size = AMDGPU_USERQ_PROC_CTX_SZ + AMDGPU_USERQ_GANG_CTX_SZ;
>>> + /* The FW expects at least one page space allocated for gang ctx. */
>>> + size = AMDGPU_USERQ_GANG_CTX_SZ;
>>> r = amdgpu_bo_create_kernel(uq_mgr->adev, size, 0,
>>> AMDGPU_GEM_DOMAIN_GTT,
>>> &ctx->obj, &ctx->gpu_addr,
>>> @@ -257,6 +253,27 @@ static int mes_userq_detect_and_reset(struct
>>> amdgpu_device *adev,
>>> return r;
>>> }
>>>
>>> +static int mes_userq_create_proc_ctx_space(struct amdgpu_userq_mgr *uq_mgr)
>>> +{
>>> + int r = 0;
>>> +
>>> + mutex_lock(&uq_mgr->userq_mutex);
>> Clear NAK. We can't allocate anything while holding that lock.
>>
>> Please add a different lock to protected the buffer or just oportunistically
>> allocate it with CMPXCHG().
>
> I will introduce a different lock in V2.
>
>>> + if (!uq_mgr->proc_ctx_obj.obj) {
>> Please drop that check, amdgpu_bo_create_kernel() should already take care
>> of that.
>
> I think we still need this check, because although amdgpu_bo_create_kernel()
> checks (!*bo_ptr), but:
> 1) it does not immediately return if bo_ptr is valid. It only skips
> re-creating the bo,
> it still calls amdgpu_bo_reserve(), amdgpu_bo_pin(), amdgpu_ttm_alloc_gart(),
> and amdgpu_bo_kmap()
> on every invocation.
>
> 2) it calls memset() unconditionally on every invocation.
>
> So I think this check is still necessary, and another thing, do you think
> amdgpu_bo_create_kernel() should immediately return if *bo_ptr is not NULL?
> It looks like this deserve a fix.
Good point, IIRC we added this handling to make it easier to re-create kernel
buffers after suspend/resume.
I'm not sure if any code path is actually still using this since we found that
for a lot of use cases you need to keep the FW buffers at the same location
even after suspend/resume.
Anyway just add an if and comment why it is necessary.
>
> Thanks
> Lingshan
>
>> Regards,
>> Christian.
>>
>>> + r = amdgpu_bo_create_kernel(uq_mgr->adev,
>>> AMDGPU_USERQ_PROC_CTX_SZ,
>>> + 0, AMDGPU_GEM_DOMAIN_GTT,
>>> + &uq_mgr->proc_ctx_obj.obj,
>>> + &uq_mgr->proc_ctx_obj.gpu_addr,
>>> + &uq_mgr->proc_ctx_obj.cpu_ptr);
>>> +
>>> + if (!r)
>>> + memset(uq_mgr->proc_ctx_obj.cpu_ptr, 0,
>>> AMDGPU_USERQ_PROC_CTX_SZ);
When amdgpu_bo_create_kernel() does that the memset here can probably be
dropped.
Regards,
Christian.
>>> + }
>>> +
>>> + mutex_unlock(&uq_mgr->userq_mutex);
>>> +
>>> + return r;
>>> +}
>>> +
>>> static int mes_userq_mqd_create(struct amdgpu_usermode_queue *queue,
>>> struct drm_amdgpu_userq_in *args_in)
>>> {
>>> @@ -429,7 +446,14 @@ static int mes_userq_mqd_create(struct
>>> amdgpu_usermode_queue *queue,
>>> goto free_mqd;
>>> }
>>>
>>> - /* Create BO for FW operations */
>>> + /* Create per-process MES process context BO */
>>> + r = mes_userq_create_proc_ctx_space(uq_mgr);
>>> + if (r) {
>>> + DRM_ERROR("Failed to allocate MES process context space bo,
>>> error: %d\n", r);
>>> + goto free_mqd;
>>> + }
>>> +
>>> + /* Create BO of a gang for FW operations */
>>> r = mes_userq_create_ctx_space(uq_mgr, queue, mqd_user);
>>> if (r) {
>>> DRM_ERROR("Failed to allocate BO for userqueue (%d)", r);
>>> @@ -492,7 +516,7 @@ static int mes_userq_preempt(struct
>>> amdgpu_usermode_queue *queue)
>>> *fence_ptr = 0;
>>>
>>> memset(&queue_input, 0x0, sizeof(struct mes_suspend_gang_input));
>>> - queue_input.gang_context_addr = ctx->gpu_addr +
>>> AMDGPU_USERQ_PROC_CTX_SZ;
>>> + queue_input.gang_context_addr = ctx->gpu_addr;
>>> queue_input.suspend_fence_addr = fence_gpu_addr;
>>> queue_input.suspend_fence_value = 1;
>>> amdgpu_mes_lock(&adev->mes);
>>> @@ -529,7 +553,7 @@ static int mes_userq_restore(struct
>>> amdgpu_usermode_queue *queue)
>>> return 0;
>>>
>>> memset(&queue_input, 0x0, sizeof(struct mes_resume_gang_input));
>>> - queue_input.gang_context_addr = ctx->gpu_addr +
>>> AMDGPU_USERQ_PROC_CTX_SZ;
>>> + queue_input.gang_context_addr = ctx->gpu_addr;
>>>
>>> amdgpu_mes_lock(&adev->mes);
>>> r = adev->mes.funcs->resume_gang(&adev->mes, &queue_input);
