[PATCH v2 1/1] drm/amdgpu: fix amdgpu_vm_pt_free warning
Felix Kuehling
felix.kuehling at amd.com
Mon Sep 12 18:48:39 UTC 2022
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.
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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