[AMD Official Use Only - AMD Internal Distribution Only]
Ping....
How about this? Currently it is easily to reproduce the issue on our environment. We need this change to fix it.
Emily Deng
Best Wishes
>-----Original Message-----
>From: amd-gfx <amd-gfx-bounces@xxxxxxxxxxxxxxxxxxxxx> On Behalf Of Deng, Emily
>Sent: Monday, January 6, 2025 9:52 AM
>To: Kuehling, Felix <Felix.Kuehling@xxxxxxx>; amd-gfx@xxxxxxxxxxxxxxxxxxxxx;
>Yang, Philip <Philip.Yang@xxxxxxx>; Koenig, Christian
><Christian.Koenig@xxxxxxx>
>Subject: RE: [PATCH v2] drm/amdgpu: Fix the looply call svm_range_restore_pages
>issue
>
>[AMD Official Use Only - AMD Internal Distribution Only]
>
>[AMD Official Use Only - AMD Internal Distribution Only]
>
>>-----Original Message-----
>>From: Kuehling, Felix <Felix.Kuehling@xxxxxxx>
>>Sent: Saturday, January 4, 2025 7:18 AM
>>To: Deng, Emily <Emily.Deng@xxxxxxx>; amd-gfx@xxxxxxxxxxxxxxxxxxxxx;
>>Yang, Philip <Philip.Yang@xxxxxxx>; Koenig, Christian
>><Christian.Koenig@xxxxxxx>
>>Subject: Re: [PATCH v2] drm/amdgpu: Fix the looply call
>>svm_range_restore_pages issue
>>
>>
>>On 2025-01-02 21:26, Emily Deng wrote:
>>> As the delayed free pt, the wanted freed bo has been reused which
>>> will cause unexpected page fault, and then call svm_range_restore_pages.
>>>
>>> Detail as below:
>>> 1.It wants to free the pt in follow code, but it is not freed
>>> immediately and used “schedule_work(&vm->pt_free_work);”.
>>>
>>> [ 92.276838] Call Trace:
>>> [ 92.276841] dump_stack+0x63/0xa0
>>> [ 92.276887] amdgpu_vm_pt_free_list+0xfb/0x120 [amdgpu]
>>> [ 92.276932] amdgpu_vm_update_range+0x69c/0x8e0 [amdgpu]
>>> [ 92.276990] svm_range_unmap_from_gpus+0x112/0x310 [amdgpu]
>>> [ 92.277046] svm_range_cpu_invalidate_pagetables+0x725/0x780 [amdgpu]
>>> [ 92.277050] ? __alloc_pages_nodemask+0x19f/0x3e0
>>> [ 92.277051] mn_itree_invalidate+0x72/0xc0
>>> [ 92.277052] __mmu_notifier_invalidate_range_start+0x48/0x60
>>> [ 92.277054] migrate_vma_collect+0xf6/0x100
>>> [ 92.277055] migrate_vma_setup+0xcf/0x120
>>> [ 92.277109] svm_migrate_ram_to_vram+0x256/0x6b0 [amdgpu]
>>>
>>> 2.Call svm_range_map_to_gpu->amdgpu_vm_update_range to update the
>>> page table, at this time it will use the same entry bo which is the
>>> want free bo in step1.
>>>
>>> 3.Then it executes the pt_free_work to free the bo. At this time, the
>>> GPU access memory will cause page fault as pt bo has been freed. And
>>> then it will call svm_range_restore_pages again.
>>>
>>> How to fix?
>>> Add a workqueue, and flush the workqueue each time before updating page table.
>>
>>I think this is kind of a known issue in the GPUVM code. Philip was
>>looking at it before.
>>
>>Just flushing a workqueue may seem like a simple and elegant solution,
>>but I'm afraid it introduces lock dependency issues. By flushing the
>>workqueue, you're effectively creating a lock dependency of the MMU
>>notifier on any locks held inside the worker function. You now get a
>>circular lock dependency with any of those locks and memory reclaim. I
>>think LOCKDEP would be able to catch that if you compile your kernel with that
>feature enabled.
>>
>>The proper solution is to prevent delayed freeing of page tables if
>>they happened to get reused, or prevent reuse of page tables if they are flagged for
>delayed freeing.
>>
>>Regards,
>> Felix
>>
>Thanks, already enabled LOCKDEP while compiling the kernel. The delay work
>seems for other reasons, I am not sure whether it could be deleted completely.
>
>Emily Deng
>Best Wishes
>>
>>>
>>> Signed-off-by: Emily Deng <Emily.Deng@xxxxxxx>
>>> ---
>>> drivers/gpu/drm/amd/amdgpu/amdgpu.h | 1 +
>>> drivers/gpu/drm/amd/amdgpu/amdgpu_amdkfd_gpuvm.c | 1 +
>>> drivers/gpu/drm/amd/amdgpu/amdgpu_vm.c | 7 +++++--
>>> drivers/gpu/drm/amd/amdgpu/amdgpu_vm_pt.c | 6 +++++-
>>> drivers/gpu/drm/amd/amdkfd/kfd_svm.c | 3 +++
>>> 5 files changed, 15 insertions(+), 3 deletions(-)
>>>
>>> diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu.h
>>> b/drivers/gpu/drm/amd/amdgpu/amdgpu.h
>>> index 93c352b08969..cbf68ad1c8d0 100644
>>> --- a/drivers/gpu/drm/amd/amdgpu/amdgpu.h
>>> +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu.h
>>> @@ -1188,6 +1188,7 @@ struct amdgpu_device {
>>> struct mutex enforce_isolation_mutex;
>>>
>>> struct amdgpu_init_level *init_lvl;
>>> + struct workqueue_struct *wq;
>>> };
>>>
>>> static inline uint32_t amdgpu_ip_version(const struct amdgpu_device
>>> *adev, diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_amdkfd_gpuvm.c
>>> b/drivers/gpu/drm/amd/amdgpu/amdgpu_amdkfd_gpuvm.c
>>> index f30548f4c3b3..5b4835bc81b3 100644
>>> --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_amdkfd_gpuvm.c
>>> +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_amdkfd_gpuvm.c
>>> @@ -2069,6 +2069,7 @@ int amdgpu_amdkfd_gpuvm_map_memory_to_gpu(
>>> if (ret)
>>> goto out;
>>> }
>>> + flush_workqueue(adev->wq);
>>>
>>> ret = reserve_bo_and_vm(mem, avm, &ctx);
>>> if (unlikely(ret))
>>> diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_vm.c
>>> b/drivers/gpu/drm/amd/amdgpu/amdgpu_vm.c
>>> index 9d6ffe38b48a..500d97cd9114 100644
>>> --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_vm.c
>>> +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_vm.c
>>> @@ -2607,7 +2607,7 @@ void amdgpu_vm_fini(struct amdgpu_device *adev,
>>struct amdgpu_vm *vm)
>>> amdgpu_amdkfd_gpuvm_destroy_cb(adev, vm);
>>>
>>> flush_work(&vm->pt_free_work);
>>> -
>>> + cancel_work_sync(&vm->pt_free_work);
>>> root = amdgpu_bo_ref(vm->root.bo);
>>> amdgpu_bo_reserve(root, true);
>>> amdgpu_vm_put_task_info(vm->task_info);
>>> @@ -2708,6 +2708,8 @@ void amdgpu_vm_manager_init(struct
>>> amdgpu_device
>>*adev)
>>> #endif
>>>
>>> xa_init_flags(&adev->vm_manager.pasids, XA_FLAGS_LOCK_IRQ);
>>> + adev->wq = alloc_workqueue("amdgpu_recycle",
>>> + WQ_MEM_RECLAIM | WQ_HIGHPRI |
>>WQ_UNBOUND, 16);
>>> }
>>>
>>> /**
>>> @@ -2721,7 +2723,8 @@ void amdgpu_vm_manager_fini(struct
>>> amdgpu_device
>>*adev)
>>> {
>>> WARN_ON(!xa_empty(&adev->vm_manager.pasids));
>>> xa_destroy(&adev->vm_manager.pasids);
>>> -
>>> + flush_workqueue(adev->wq);
>>> + destroy_workqueue(adev->wq);
>>> amdgpu_vmid_mgr_fini(adev);
>>> }
>>>
>>> diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_vm_pt.c
>>> b/drivers/gpu/drm/amd/amdgpu/amdgpu_vm_pt.c
>>> index f78a0434a48f..1204406215ee 100644
>>> --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_vm_pt.c
>>> +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_vm_pt.c
>>> @@ -554,15 +554,19 @@ void amdgpu_vm_pt_free_work(struct work_struct
>>> *work)
>>>
>>> vm = container_of(work, struct amdgpu_vm, pt_free_work);
>>>
>>> + printk("Emily:%s\n", __func__);
>>> spin_lock(&vm->status_lock);
>>> list_splice_init(&vm->pt_freed, &pt_freed);
>>> spin_unlock(&vm->status_lock);
>>> + printk("Emily:%s 1\n", __func__);
>>>
>>> /* flush_work in amdgpu_vm_fini ensure vm->root.bo is valid. */
>>> amdgpu_bo_reserve(vm->root.bo, true);
>>> + printk("Emily:%s 2\n", __func__);
>>>
>>> list_for_each_entry_safe(entry, next, &pt_freed, vm_status)
>>> amdgpu_vm_pt_free(entry);
>>> + printk("Emily:%s 3\n", __func__);
>>>
>>> amdgpu_bo_unreserve(vm->root.bo);
>>> }
>>> @@ -589,7 +593,7 @@ void amdgpu_vm_pt_free_list(struct amdgpu_device
>>*adev,
>>> spin_lock(&vm->status_lock);
>>> list_splice_init(¶ms->tlb_flush_waitlist, &vm->pt_freed);
>>> spin_unlock(&vm->status_lock);
>>> - schedule_work(&vm->pt_free_work);
>>> + queue_work(adev->wq, &vm->pt_free_work);
>>> return;
>>> }
>>>
>>> diff --git a/drivers/gpu/drm/amd/amdkfd/kfd_svm.c
>>> b/drivers/gpu/drm/amd/amdkfd/kfd_svm.c
>>> index 3e2911895c74..55edf96d5a95 100644
>>> --- a/drivers/gpu/drm/amd/amdkfd/kfd_svm.c
>>> +++ b/drivers/gpu/drm/amd/amdkfd/kfd_svm.c
>>> @@ -1314,6 +1314,7 @@ svm_range_unmap_from_gpu(struct amdgpu_device
>>*adev, struct amdgpu_vm *vm,
>>> uint64_t init_pte_value = 0;
>>>
>>> pr_debug("[0x%llx 0x%llx]\n", start, last);
>>> + flush_workqueue(adev->wq);
>>>
>>> return amdgpu_vm_update_range(adev, vm, false, true, true,
>>> false, NULL,
>>start,
>>> last, init_pte_value, 0, 0, NULL,
>>> NULL, @@ -1422,6
>>+1423,8
>>> @@ svm_range_map_to_gpu(struct kfd_process_device *pdd, struct
>>> svm_range
>>*prange,
>>> * different memory partition based on fpfn/lpfn, we should use
>>> * same vm_manager.vram_base_offset regardless memory partition.
>>> */
>>> + flush_workqueue(adev->wq);
>>> +
>>> r = amdgpu_vm_update_range(adev, vm, false, false, flush_tlb, true,
>>> NULL, last_start, prange->start + i,
>>> pte_flags,
