[PATCH v2 1/1] drm/amdgpu: fix amdgpu_vm_pt_free warning
Christian König
christian.koenig at amd.com
Mon Sep 12 18:59:47 UTC 2022
Am 12.09.22 um 20:48 schrieb Felix Kuehling:
> Am 2022-09-12 um 13:58 schrieb Philip Yang:
>> Free page table BO from vm resv unlocked context generate below
>> warnings.
>>
>> Add a free_bo_work in vm to free page able BO from vm->bo_freed list.
>> pass vm resv unlock status from page table update caller, and add vm_bo
>> entry to vm->bo_freed_list and schedule the work if calling with vm resv
>> unlocked.
>>
>> WARNING: CPU: 12 PID: 3238 at
>> drivers/gpu/drm/ttm/ttm_bo.c:106 ttm_bo_set_bulk_move+0xa1/0xc0
>> Call Trace:
>> amdgpu_vm_pt_free+0x42/0xd0 [amdgpu]
>> amdgpu_vm_pt_free_dfs+0xb3/0xf0 [amdgpu]
>> amdgpu_vm_ptes_update+0x52d/0x850 [amdgpu]
>> amdgpu_vm_update_range+0x2a6/0x640 [amdgpu]
>> svm_range_unmap_from_gpus+0x110/0x300 [amdgpu]
>> svm_range_cpu_invalidate_pagetables+0x535/0x600 [amdgpu]
>> __mmu_notifier_invalidate_range_start+0x1cd/0x230
>> unmap_vmas+0x9d/0x140
>> unmap_region+0xa8/0x110
>>
>> WARNING: CPU: 0 PID: 1475 at
>> drivers/dma-buf/dma-resv.c:483 dma_resv_iter_next
>> Call Trace:
>> dma_resv_iter_first+0x43/0xa0
>> amdgpu_vm_sdma_update+0x69/0x2d0 [amdgpu]
>> amdgpu_vm_ptes_update+0x29c/0x870 [amdgpu]
>> amdgpu_vm_update_range+0x2f6/0x6c0 [amdgpu]
>> svm_range_unmap_from_gpus+0x115/0x300 [amdgpu]
>> svm_range_cpu_invalidate_pagetables+0x510/0x5e0 [amdgpu]
>> __mmu_notifier_invalidate_range_start+0x1d3/0x230
>> unmap_vmas+0x140/0x150
>> unmap_region+0xa8/0x110
>>
>> Signed-off-by: Philip Yang <Philip.Yang at amd.com>
>> ---
>> drivers/gpu/drm/amd/amdgpu/amdgpu_vm.c | 4 ++
>> drivers/gpu/drm/amd/amdgpu/amdgpu_vm.h | 6 +++
>> drivers/gpu/drm/amd/amdgpu/amdgpu_vm_pt.c | 51 ++++++++++++++++++++---
>> 3 files changed, 55 insertions(+), 6 deletions(-)
>>
>> diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_vm.c
>> b/drivers/gpu/drm/amd/amdgpu/amdgpu_vm.c
>> index 59cac347baa3..add3b08ffde9 100644
>> --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_vm.c
>> +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_vm.c
>> @@ -2022,6 +2022,9 @@ int amdgpu_vm_init(struct amdgpu_device *adev,
>> struct amdgpu_vm *vm)
>> spin_lock_init(&vm->invalidated_lock);
>> INIT_LIST_HEAD(&vm->freed);
>> INIT_LIST_HEAD(&vm->done);
>> + INIT_LIST_HEAD(&vm->bo_freed);
>> + INIT_WORK(&vm->bo_free_work, amdgpu_vm_pt_free_work);
>> + spin_lock_init(&vm->bo_free_lock);
>> /* create scheduler entities for page table updates */
>> r = drm_sched_entity_init(&vm->immediate,
>> DRM_SCHED_PRIORITY_NORMAL,
>> @@ -2244,6 +2247,7 @@ void amdgpu_vm_fini(struct amdgpu_device *adev,
>> struct amdgpu_vm *vm)
>> amdgpu_vm_free_mapping(adev, vm, mapping, NULL);
>> }
>> + cancel_work_sync(&vm->bo_free_work);
>> amdgpu_vm_pt_free_root(adev, vm);
>> amdgpu_bo_unreserve(root);
>> amdgpu_bo_unref(&root);
>> diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_vm.h
>> b/drivers/gpu/drm/amd/amdgpu/amdgpu_vm.h
>> index 9ecb7f663e19..c8c59c66ca2f 100644
>> --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_vm.h
>> +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_vm.h
>> @@ -276,6 +276,11 @@ struct amdgpu_vm {
>> /* BOs which are invalidated, has been updated in the PTs */
>> struct list_head done;
>> + /* PT BOs scheduled to free and fill with zero if vm_resv is
>> not hold */
>> + struct list_head bo_freed;
>> + struct work_struct bo_free_work;
>> + spinlock_t bo_free_lock;
>> +
>> /* contains the page directory */
>> struct amdgpu_vm_bo_base root;
>> struct dma_fence *last_update;
>> @@ -471,6 +476,7 @@ int amdgpu_vm_pde_update(struct
>> amdgpu_vm_update_params *params,
>> int amdgpu_vm_ptes_update(struct amdgpu_vm_update_params *params,
>> uint64_t start, uint64_t end,
>> uint64_t dst, uint64_t flags);
>> +void amdgpu_vm_pt_free_work(struct work_struct *work);
>> #if defined(CONFIG_DEBUG_FS)
>> void amdgpu_debugfs_vm_bo_info(struct amdgpu_vm *vm, struct
>> seq_file *m);
>> diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_vm_pt.c
>> b/drivers/gpu/drm/amd/amdgpu/amdgpu_vm_pt.c
>> index 88de9f0d4728..12471ef126a9 100644
>> --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_vm_pt.c
>> +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_vm_pt.c
>> @@ -624,12 +624,22 @@ static int amdgpu_vm_pt_alloc(struct
>> amdgpu_device *adev,
>> *
>> * @entry: PDE to free
>> */
>> -static void amdgpu_vm_pt_free(struct amdgpu_vm_bo_base *entry)
>> +static void amdgpu_vm_pt_free(struct amdgpu_vm_bo_base *entry, bool
>> unlocked)
>> {
>> struct amdgpu_bo *shadow;
>> if (!entry->bo)
>> return;
>> +
>> + if (unlocked) {
>> + spin_lock(&entry->vm->bo_free_lock);
>> + list_move(&entry->vm_status, &entry->vm->bo_freed);
>> + spin_unlock(&entry->vm->bo_free_lock);
>> +
>> + schedule_work(&entry->vm->bo_free_work);
>> + return;
>> + }
>> +
>> shadow = amdgpu_bo_shadowed(entry->bo);
>> if (shadow) {
>> ttm_bo_set_bulk_move(&shadow->tbo, NULL);
>> @@ -641,6 +651,33 @@ static void amdgpu_vm_pt_free(struct
>> amdgpu_vm_bo_base *entry)
>> amdgpu_bo_unref(&entry->bo);
>> }
>> +void amdgpu_vm_pt_free_work(struct work_struct *work)
>> +{
>> + struct amdgpu_vm_bo_base *entry;
>> + struct amdgpu_vm *vm;
>> + struct amdgpu_bo *root;
>> +
>> + vm = container_of(work, struct amdgpu_vm, bo_free_work);
>> +
>> + root = amdgpu_bo_ref(vm->root.bo);
>> + amdgpu_bo_reserve(root, true);
>> +
>> + spin_lock(&vm->bo_free_lock);
>> + while (!list_empty(&vm->bo_freed)) {
>> + entry = list_first_entry(&vm->bo_freed, struct
>> amdgpu_vm_bo_base,
>> + vm_status);
>
> I don't see where you're removing the entry from the list. You need a
> list_del_init here.
>
> If you're relying on the list_del call in amdgpu_vm_pt_free, that's
> not safe because it's outside the spinlock. This could end up
> corrupting the list if another thread is concurrently adding to the
> same list.
It's much easier to use list_splice() to move the list to a local head
and then traverse it with list_for_each_entry_safe() and free up everything.
Regards,
Christian.
>
> Regards,
> Felix
>
>
>> + spin_unlock(&vm->bo_free_lock);
>> +
>> + amdgpu_vm_pt_free(entry, false);
>> +
>> + spin_lock(&vm->bo_free_lock);
>> + }
>> + spin_unlock(&vm->bo_free_lock);
>> +
>> + amdgpu_bo_unreserve(root);
>> + amdgpu_bo_unref(&root);
>> +}
>> +
>> /**
>> * amdgpu_vm_pt_free_dfs - free PD/PT levels
>> *
>> @@ -652,16 +689,17 @@ static void amdgpu_vm_pt_free(struct
>> amdgpu_vm_bo_base *entry)
>> */
>> static void amdgpu_vm_pt_free_dfs(struct amdgpu_device *adev,
>> struct amdgpu_vm *vm,
>> - struct amdgpu_vm_pt_cursor *start)
>> + struct amdgpu_vm_pt_cursor *start,
>> + bool unlocked)
>> {
>> struct amdgpu_vm_pt_cursor cursor;
>> struct amdgpu_vm_bo_base *entry;
>> for_each_amdgpu_vm_pt_dfs_safe(adev, vm, start, cursor, entry)
>> - amdgpu_vm_pt_free(entry);
>> + amdgpu_vm_pt_free(entry, unlocked);
>> if (start)
>> - amdgpu_vm_pt_free(start->entry);
>> + amdgpu_vm_pt_free(start->entry, unlocked);
>> }
>> /**
>> @@ -673,7 +711,7 @@ static void amdgpu_vm_pt_free_dfs(struct
>> amdgpu_device *adev,
>> */
>> void amdgpu_vm_pt_free_root(struct amdgpu_device *adev, struct
>> amdgpu_vm *vm)
>> {
>> - amdgpu_vm_pt_free_dfs(adev, vm, NULL);
>> + amdgpu_vm_pt_free_dfs(adev, vm, NULL, false);
>> }
>> /**
>> @@ -966,7 +1004,8 @@ int amdgpu_vm_ptes_update(struct
>> amdgpu_vm_update_params *params,
>> if (cursor.entry->bo) {
>> params->table_freed = true;
>> amdgpu_vm_pt_free_dfs(adev, params->vm,
>> - &cursor);
>> + &cursor,
>> + params->unlocked);
>> }
>> amdgpu_vm_pt_next(adev, &cursor);
>> }
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