[PATCH v5 1/1] drm/amdgpu: Fix amdgpu_vm_pt_free warning
Philip Yang
yangp at amd.com
Thu Sep 15 14:39:15 UTC 2022
On 2022-09-15 02:21, Christian König wrote:
> Am 14.09.22 um 19:45 schrieb Felix Kuehling:
>> Am 2022-09-14 um 12:08 schrieb Philip Yang:
>>> Free page table BO from vm resv unlocked context generate below
>>> warnings.
>>>
>>> Add a pt_free_work in vm to free page table BO from vm->pt_freed list.
>>> pass vm resv unlock status from page table update caller, and add vm_bo
>>> entry to vm->pt_freed list and schedule the pt_free_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
>>>
>>> Signed-off-by: Philip Yang <Philip.Yang at amd.com>
>>> ---
>>> drivers/gpu/drm/amd/amdgpu/amdgpu_vm.c | 5 +++
>>> drivers/gpu/drm/amd/amdgpu/amdgpu_vm.h | 6 ++++
>>> drivers/gpu/drm/amd/amdgpu/amdgpu_vm_pt.c | 41
>>> +++++++++++++++++++++--
>>> 3 files changed, 49 insertions(+), 3 deletions(-)
>>>
>>> diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_vm.c
>>> b/drivers/gpu/drm/amd/amdgpu/amdgpu_vm.c
>>> index 59cac347baa3..20cfc8c9635b 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->pt_freed);
>>> + INIT_WORK(&vm->pt_free_work, amdgpu_vm_pt_free_work);
>>> + spin_lock_init(&vm->pt_free_lock);
>>> /* create scheduler entities for page table updates */
>>> r = drm_sched_entity_init(&vm->immediate,
>>> DRM_SCHED_PRIORITY_NORMAL,
>>> @@ -2223,6 +2226,8 @@ 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);
>>> +
>>> root = amdgpu_bo_ref(vm->root.bo);
>>> amdgpu_bo_reserve(root, true);
>>> amdgpu_vm_set_pasid(adev, vm, 0);
>>> diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_vm.h
>>> b/drivers/gpu/drm/amd/amdgpu/amdgpu_vm.h
>>> index 9ecb7f663e19..b77fe838c327 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 pt_freed;
>>> + struct work_struct pt_free_work;
>>> + spinlock_t pt_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..c16579471f22 100644
>>> --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_vm_pt.c
>>> +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_vm_pt.c
>>> @@ -641,6 +641,27 @@ 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, *next;
>>> + struct amdgpu_vm *vm;
>>> + LIST_HEAD(pt_freed);
>>> +
>>> + vm = container_of(work, struct amdgpu_vm, pt_free_work);
>>> +
>>> + spin_lock(&vm->pt_free_lock);
>>> + list_splice_init(&vm->pt_freed, &pt_freed);
>>> + spin_unlock(&vm->pt_free_lock);
>>> +
>>> + // flush_work in amdgpu_vm_fini ensure vm->root.bo is valid
>>> + amdgpu_bo_reserve(vm->root.bo, true);
>>> +
>>> + list_for_each_entry_safe(entry, next, &pt_freed, vm_status)
>>> + amdgpu_vm_pt_free(entry);
>>> +
>>> + amdgpu_bo_unreserve(vm->root.bo);
>>> +}
>>> +
>>> /**
>>> * amdgpu_vm_pt_free_dfs - free PD/PT levels
>>> *
>>> @@ -652,11 +673,24 @@ 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;
>>> + if (unlocked) {
>>> + spin_lock(&vm->pt_free_lock);
>>> + for_each_amdgpu_vm_pt_dfs_safe(adev, vm, start, cursor, entry)
>>> + list_move(&entry->vm_status, &vm->pt_freed);
>>> +
>>> + if (start)
>>> + list_move(&start->entry->vm_status, &vm->pt_freed);
>>> + spin_unlock(&vm->pt_free_lock);
>>
>> Question for Christian: list_move will take the entry off another
>> vm_status list (evicted, idle, invalidated, relocated). I don't think
>> this is safe without holding a reservation lock in most cases. Since
>> the point here is to maintain a list of PTs to be freed without
>> locking a reservation, is the vm_status really the right way to do this?
>
> Oh, good point. This means we need to protect the whole state machine
> with a spinlock or use a separate deleted list.
>
> I don't see how we can easily use a separate list here, but we already
> have the invalidated_lock, maybe we need to rename this one to status
> lock and use it for all cases.
Rename invalidate_lock to status_lock, then we can use it for
vm->pt_freed list, don't need another vm->pt_free_lock, this is good.
invalidate_lock is used to protect list vm->invalidate and vm->done
right now, other vm list evicted/relocated/moved/idle/freed are
protected by reservation lock. Do we need protect all vm lists
operations with status_lock as well to ensure it is safe to take entry
from vm_status lists for unlocked context?
Regards,
Philip
>
> Regards,
> Christian.
>
>>
>> Regards,
>> Felix
>>
>>
>>> + schedule_work(&vm->pt_free_work);
>>> + return;
>>> + }
>>> +
>>> for_each_amdgpu_vm_pt_dfs_safe(adev, vm, start, cursor, entry)
>>> amdgpu_vm_pt_free(entry);
>>> @@ -673,7 +707,7 @@ 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 +1000,8 @@ 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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