On 5/26/2026 4:46 PM, Christian König wrote:
> 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.
oops, I missed this comment.
amdgpu_bo_create_reserved() sets the struct amdgpu_bo_param all zero by
memset(&bp, 0, sizeof(bp)), and amdgpu_bo_create() kvzalloc a struct amdgpu_bo.
However I think we need to set the BO all zero, just like what
mes_userq_create_ctx_space() does.
Thanks
Lingshan
>
> 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);
