[PATCH] drm/amdgpu: Add notifier lock for KFD userptrs

Chen, Xiaogang xiaogang.chen at amd.com
Thu Dec 8 08:42:06 UTC 2022


On 12/5/2022 6:54 PM, Felix Kuehling wrote:
> Add a per-process MMU notifier lock for processing notifiers from
> userptrs. Use that lock to properly synchronize page table updates with
> MMU notifiers.
>
> v2: rebased
>
> Signed-off-by: Felix Kuehling <Felix.Kuehling at amd.com>
> Reviewed-by: Xiaogang Chen<Xiaogang.Chen at amd.com> (v1)

This patch is reviewed-by: Xiaogang Chen<Xiaogang.Chen at amd.com>

Regards

Xiaogang

> ---
>   drivers/gpu/drm/amd/amdgpu/amdgpu_amdkfd.h    |  13 +-
>   .../gpu/drm/amd/amdgpu/amdgpu_amdkfd_gpuvm.c  | 212 ++++++++++++------
>   drivers/gpu/drm/amd/amdgpu/amdgpu_hmm.c       |  12 +-
>   drivers/gpu/drm/amd/amdgpu/amdgpu_hmm.h       |   3 +-
>   drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c       |  17 +-
>   drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.h       |   6 +
>   6 files changed, 172 insertions(+), 91 deletions(-)
>
> diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_amdkfd.h b/drivers/gpu/drm/amd/amdgpu/amdgpu_amdkfd.h
> index f50e3ba4d7a5..589939631ed4 100644
> --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_amdkfd.h
> +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_amdkfd.h
> @@ -29,6 +29,7 @@
>   #include <linux/mm.h>
>   #include <linux/kthread.h>
>   #include <linux/workqueue.h>
> +#include <linux/mmu_notifier.h>
>   #include <kgd_kfd_interface.h>
>   #include <drm/ttm/ttm_execbuf_util.h>
>   #include "amdgpu_sync.h"
> @@ -65,6 +66,7 @@ struct kgd_mem {
>   	struct mutex lock;
>   	struct amdgpu_bo *bo;
>   	struct dma_buf *dmabuf;
> +	struct hmm_range *range;
>   	struct list_head attachments;
>   	/* protected by amdkfd_process_info.lock */
>   	struct ttm_validate_buffer validate_list;
> @@ -75,7 +77,7 @@ struct kgd_mem {
>   
>   	uint32_t alloc_flags;
>   
> -	atomic_t invalid;
> +	uint32_t invalid;
>   	struct amdkfd_process_info *process_info;
>   
>   	struct amdgpu_sync sync;
> @@ -131,7 +133,8 @@ struct amdkfd_process_info {
>   	struct amdgpu_amdkfd_fence *eviction_fence;
>   
>   	/* MMU-notifier related fields */
> -	atomic_t evicted_bos;
> +	struct mutex notifier_lock;
> +	uint32_t evicted_bos;
>   	struct delayed_work restore_userptr_work;
>   	struct pid *pid;
>   	bool block_mmu_notifications;
> @@ -180,7 +183,8 @@ int kfd_debugfs_kfd_mem_limits(struct seq_file *m, void *data);
>   bool amdkfd_fence_check_mm(struct dma_fence *f, struct mm_struct *mm);
>   struct amdgpu_amdkfd_fence *to_amdgpu_amdkfd_fence(struct dma_fence *f);
>   int amdgpu_amdkfd_remove_fence_on_pt_pd_bos(struct amdgpu_bo *bo);
> -int amdgpu_amdkfd_evict_userptr(struct kgd_mem *mem, struct mm_struct *mm);
> +int amdgpu_amdkfd_evict_userptr(struct mmu_interval_notifier *mni,
> +				unsigned long cur_seq, struct kgd_mem *mem);
>   #else
>   static inline
>   bool amdkfd_fence_check_mm(struct dma_fence *f, struct mm_struct *mm)
> @@ -201,7 +205,8 @@ int amdgpu_amdkfd_remove_fence_on_pt_pd_bos(struct amdgpu_bo *bo)
>   }
>   
>   static inline
> -int amdgpu_amdkfd_evict_userptr(struct kgd_mem *mem, struct mm_struct *mm)
> +int amdgpu_amdkfd_evict_userptr(struct mmu_interval_notifier *mni,
> +				unsigned long cur_seq, struct kgd_mem *mem)
>   {
>   	return 0;
>   }
> diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_amdkfd_gpuvm.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_amdkfd_gpuvm.c
> index 8782916e64a0..0a854bb8b47e 100644
> --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_amdkfd_gpuvm.c
> +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_amdkfd_gpuvm.c
> @@ -964,7 +964,9 @@ static int init_user_pages(struct kgd_mem *mem, uint64_t user_addr,
>   		 * later stage when it is scheduled by another ioctl called by
>   		 * CRIU master process for the target pid for restore.
>   		 */
> -		atomic_inc(&mem->invalid);
> +		mutex_lock(&process_info->notifier_lock);
> +		mem->invalid++;
> +		mutex_unlock(&process_info->notifier_lock);
>   		mutex_unlock(&process_info->lock);
>   		return 0;
>   	}
> @@ -1301,6 +1303,7 @@ static int init_kfd_vm(struct amdgpu_vm *vm, void **process_info,
>   			return -ENOMEM;
>   
>   		mutex_init(&info->lock);
> +		mutex_init(&info->notifier_lock);
>   		INIT_LIST_HEAD(&info->vm_list_head);
>   		INIT_LIST_HEAD(&info->kfd_bo_list);
>   		INIT_LIST_HEAD(&info->userptr_valid_list);
> @@ -1317,7 +1320,6 @@ static int init_kfd_vm(struct amdgpu_vm *vm, void **process_info,
>   		}
>   
>   		info->pid = get_task_pid(current->group_leader, PIDTYPE_PID);
> -		atomic_set(&info->evicted_bos, 0);
>   		INIT_DELAYED_WORK(&info->restore_userptr_work,
>   				  amdgpu_amdkfd_restore_userptr_worker);
>   
> @@ -1372,6 +1374,7 @@ static int init_kfd_vm(struct amdgpu_vm *vm, void **process_info,
>   		put_pid(info->pid);
>   create_evict_fence_fail:
>   		mutex_destroy(&info->lock);
> +		mutex_destroy(&info->notifier_lock);
>   		kfree(info);
>   	}
>   	return ret;
> @@ -1496,6 +1499,7 @@ void amdgpu_amdkfd_gpuvm_destroy_cb(struct amdgpu_device *adev,
>   		cancel_delayed_work_sync(&process_info->restore_userptr_work);
>   		put_pid(process_info->pid);
>   		mutex_destroy(&process_info->lock);
> +		mutex_destroy(&process_info->notifier_lock);
>   		kfree(process_info);
>   	}
>   }
> @@ -1548,7 +1552,9 @@ int amdgpu_amdkfd_criu_resume(void *p)
>   
>   	mutex_lock(&pinfo->lock);
>   	pr_debug("scheduling work\n");
> -	atomic_inc(&pinfo->evicted_bos);
> +	mutex_lock(&pinfo->notifier_lock);
> +	pinfo->evicted_bos++;
> +	mutex_unlock(&pinfo->notifier_lock);
>   	if (!READ_ONCE(pinfo->block_mmu_notifications)) {
>   		ret = -EINVAL;
>   		goto out_unlock;
> @@ -1773,8 +1779,13 @@ int amdgpu_amdkfd_gpuvm_free_memory_of_gpu(
>   	list_del(&bo_list_entry->head);
>   	mutex_unlock(&process_info->lock);
>   
> -	/* No more MMU notifiers */
> -	amdgpu_hmm_unregister(mem->bo);
> +	/* Cleanup user pages and MMU notifiers */
> +	if (amdgpu_ttm_tt_get_usermm(mem->bo->tbo.ttm)) {
> +		amdgpu_hmm_unregister(mem->bo);
> +		mutex_lock(&process_info->notifier_lock);
> +		amdgpu_ttm_tt_discard_user_pages(mem->bo->tbo.ttm, mem->range);
> +		mutex_unlock(&process_info->notifier_lock);
> +	}
>   
>   	ret = reserve_bo_and_cond_vms(mem, NULL, BO_VM_ALL, &ctx);
>   	if (unlikely(ret))
> @@ -1864,6 +1875,16 @@ int amdgpu_amdkfd_gpuvm_map_memory_to_gpu(
>   	 */
>   	mutex_lock(&mem->process_info->lock);
>   
> +	/* Lock notifier lock. If we find an invalid userptr BO, we can be
> +	 * sure that the MMU notifier is no longer running
> +	 * concurrently and the queues are actually stopped
> +	 */
> +	if (amdgpu_ttm_tt_get_usermm(bo->tbo.ttm)) {
> +		mutex_lock(&mem->process_info->notifier_lock);
> +		is_invalid_userptr = !!mem->invalid;
> +		mutex_unlock(&mem->process_info->notifier_lock);
> +	}
> +
>   	mutex_lock(&mem->lock);
>   
>   	domain = mem->domain;
> @@ -2241,34 +2262,38 @@ int amdgpu_amdkfd_gpuvm_import_dmabuf(struct amdgpu_device *adev,
>    *
>    * Runs in MMU notifier, may be in RECLAIM_FS context. This means it
>    * cannot do any memory allocations, and cannot take any locks that
> - * are held elsewhere while allocating memory. Therefore this is as
> - * simple as possible, using atomic counters.
> + * are held elsewhere while allocating memory.
>    *
>    * It doesn't do anything to the BO itself. The real work happens in
>    * restore, where we get updated page addresses. This function only
>    * ensures that GPU access to the BO is stopped.
>    */
> -int amdgpu_amdkfd_evict_userptr(struct kgd_mem *mem,
> -				struct mm_struct *mm)
> +int amdgpu_amdkfd_evict_userptr(struct mmu_interval_notifier *mni,
> +				unsigned long cur_seq, struct kgd_mem *mem)
>   {
>   	struct amdkfd_process_info *process_info = mem->process_info;
> -	int evicted_bos;
>   	int r = 0;
>   
> -	/* Do not process MMU notifications until stage-4 IOCTL is received */
> +	/* Do not process MMU notifications during CRIU restore until
> +	 * KFD_CRIU_OP_RESUME IOCTL is received
> +	 */
>   	if (READ_ONCE(process_info->block_mmu_notifications))
>   		return 0;
>   
> -	atomic_inc(&mem->invalid);
> -	evicted_bos = atomic_inc_return(&process_info->evicted_bos);
> -	if (evicted_bos == 1) {
> +	mutex_lock(&process_info->notifier_lock);
> +	mmu_interval_set_seq(mni, cur_seq);
> +
> +	mem->invalid++;
> +	if (++process_info->evicted_bos == 1) {
>   		/* First eviction, stop the queues */
> -		r = kgd2kfd_quiesce_mm(mm, KFD_QUEUE_EVICTION_TRIGGER_USERPTR);
> +		r = kgd2kfd_quiesce_mm(mni->mm,
> +				       KFD_QUEUE_EVICTION_TRIGGER_USERPTR);
>   		if (r)
>   			pr_err("Failed to quiesce KFD\n");
>   		schedule_delayed_work(&process_info->restore_userptr_work,
>   			msecs_to_jiffies(AMDGPU_USERPTR_RESTORE_DELAY_MS));
>   	}
> +	mutex_unlock(&process_info->notifier_lock);
>   
>   	return r;
>   }
> @@ -2285,54 +2310,58 @@ static int update_invalid_user_pages(struct amdkfd_process_info *process_info,
>   	struct kgd_mem *mem, *tmp_mem;
>   	struct amdgpu_bo *bo;
>   	struct ttm_operation_ctx ctx = { false, false };
> -	int invalid, ret;
> +	uint32_t invalid;
> +	int ret = 0;
>   
> -	/* Move all invalidated BOs to the userptr_inval_list and
> -	 * release their user pages by migration to the CPU domain
> -	 */
> +	mutex_lock(&process_info->notifier_lock);
> +
> +	/* Move all invalidated BOs to the userptr_inval_list */
>   	list_for_each_entry_safe(mem, tmp_mem,
>   				 &process_info->userptr_valid_list,
> -				 validate_list.head) {
> -		if (!atomic_read(&mem->invalid))
> -			continue; /* BO is still valid */
> -
> -		bo = mem->bo;
> -
> -		if (amdgpu_bo_reserve(bo, true))
> -			return -EAGAIN;
> -		amdgpu_bo_placement_from_domain(bo, AMDGPU_GEM_DOMAIN_CPU);
> -		ret = ttm_bo_validate(&bo->tbo, &bo->placement, &ctx);
> -		amdgpu_bo_unreserve(bo);
> -		if (ret) {
> -			pr_err("%s: Failed to invalidate userptr BO\n",
> -			       __func__);
> -			return -EAGAIN;
> -		}
> -
> -		list_move_tail(&mem->validate_list.head,
> -			       &process_info->userptr_inval_list);
> -	}
> -
> -	if (list_empty(&process_info->userptr_inval_list))
> -		return 0; /* All evicted userptr BOs were freed */
> +				 validate_list.head)
> +		if (mem->invalid)
> +			list_move_tail(&mem->validate_list.head,
> +				       &process_info->userptr_inval_list);
>   
>   	/* Go through userptr_inval_list and update any invalid user_pages */
>   	list_for_each_entry(mem, &process_info->userptr_inval_list,
>   			    validate_list.head) {
> -		struct hmm_range *range;
> -
> -		invalid = atomic_read(&mem->invalid);
> +		invalid = mem->invalid;
>   		if (!invalid)
>   			/* BO hasn't been invalidated since the last
> -			 * revalidation attempt. Keep its BO list.
> +			 * revalidation attempt. Keep its page list.
>   			 */
>   			continue;
>   
>   		bo = mem->bo;
>   
> +		amdgpu_ttm_tt_discard_user_pages(bo->tbo.ttm, mem->range);
> +		mem->range = NULL;
> +
> +		/* BO reservations and getting user pages (hmm_range_fault)
> +		 * must happen outside the notifier lock
> +		 */
> +		mutex_unlock(&process_info->notifier_lock);
> +
> +		/* Move the BO to system (CPU) domain if necessary to unmap
> +		 * and free the SG table
> +		 */
> +		if (bo->tbo.resource->mem_type != TTM_PL_SYSTEM) {
> +			if (amdgpu_bo_reserve(bo, true))
> +				return -EAGAIN;
> +			amdgpu_bo_placement_from_domain(bo, AMDGPU_GEM_DOMAIN_CPU);
> +			ret = ttm_bo_validate(&bo->tbo, &bo->placement, &ctx);
> +			amdgpu_bo_unreserve(bo);
> +			if (ret) {
> +				pr_err("%s: Failed to invalidate userptr BO\n",
> +				       __func__);
> +				return -EAGAIN;
> +			}
> +		}
> +
>   		/* Get updated user pages */
>   		ret = amdgpu_ttm_tt_get_user_pages(bo, bo->tbo.ttm->pages,
> -						   &range);
> +						   &mem->range);
>   		if (ret) {
>   			pr_debug("Failed %d to get user pages\n", ret);
>   
> @@ -2345,30 +2374,32 @@ static int update_invalid_user_pages(struct amdkfd_process_info *process_info,
>   			 */
>   			if (ret != -EFAULT)
>   				return ret;
> -		} else {
>   
> -			/*
> -			 * FIXME: Cannot ignore the return code, must hold
> -			 * notifier_lock
> -			 */
> -			amdgpu_ttm_tt_get_user_pages_done(bo->tbo.ttm, range);
> +			ret = 0;
>   		}
>   
> +		mutex_lock(&process_info->notifier_lock);
> +
>   		/* Mark the BO as valid unless it was invalidated
>   		 * again concurrently.
>   		 */
> -		if (atomic_cmpxchg(&mem->invalid, invalid, 0) != invalid)
> -			return -EAGAIN;
> +		if (mem->invalid != invalid) {
> +			ret = -EAGAIN;
> +			goto unlock_out;
> +		}
> +		mem->invalid = 0;
>   	}
>   
> -	return 0;
> +unlock_out:
> +	mutex_unlock(&process_info->notifier_lock);
> +
> +	return ret;
>   }
>   
>   /* Validate invalid userptr BOs
>    *
> - * Validates BOs on the userptr_inval_list, and moves them back to the
> - * userptr_valid_list. Also updates GPUVM page tables with new page
> - * addresses and waits for the page table updates to complete.
> + * Validates BOs on the userptr_inval_list. Also updates GPUVM page tables
> + * with new page addresses and waits for the page table updates to complete.
>    */
>   static int validate_invalid_user_pages(struct amdkfd_process_info *process_info)
>   {
> @@ -2439,9 +2470,6 @@ static int validate_invalid_user_pages(struct amdkfd_process_info *process_info)
>   			}
>   		}
>   
> -		list_move_tail(&mem->validate_list.head,
> -			       &process_info->userptr_valid_list);
> -
>   		/* Update mapping. If the BO was not validated
>   		 * (because we couldn't get user pages), this will
>   		 * clear the page table entries, which will result in
> @@ -2457,7 +2485,9 @@ static int validate_invalid_user_pages(struct amdkfd_process_info *process_info)
>   			if (ret) {
>   				pr_err("%s: update PTE failed\n", __func__);
>   				/* make sure this gets validated again */
> -				atomic_inc(&mem->invalid);
> +				mutex_lock(&process_info->notifier_lock);
> +				mem->invalid++;
> +				mutex_unlock(&process_info->notifier_lock);
>   				goto unreserve_out;
>   			}
>   		}
> @@ -2477,6 +2507,36 @@ static int validate_invalid_user_pages(struct amdkfd_process_info *process_info)
>   	return ret;
>   }
>   
> +/* Confirm that all user pages are valid while holding the notifier lock
> + *
> + * Moves valid BOs from the userptr_inval_list back to userptr_val_list.
> + */
> +static int confirm_valid_user_pages_locked(struct amdkfd_process_info *process_info)
> +{
> +	struct kgd_mem *mem, *tmp_mem;
> +	int ret = 0;
> +
> +	list_for_each_entry_safe(mem, tmp_mem,
> +				 &process_info->userptr_inval_list,
> +				 validate_list.head) {
> +		bool valid = amdgpu_ttm_tt_get_user_pages_done(
> +				mem->bo->tbo.ttm, mem->range);
> +
> +		mem->range = NULL;
> +		if (!valid) {
> +			WARN(!mem->invalid, "Invalid BO not marked invalid");
> +			ret = -EAGAIN;
> +			continue;
> +		}
> +		WARN(mem->invalid, "Valid BO is marked invalid");
> +
> +		list_move_tail(&mem->validate_list.head,
> +			       &process_info->userptr_valid_list);
> +	}
> +
> +	return ret;
> +}
> +
>   /* Worker callback to restore evicted userptr BOs
>    *
>    * Tries to update and validate all userptr BOs. If successful and no
> @@ -2491,9 +2551,11 @@ static void amdgpu_amdkfd_restore_userptr_worker(struct work_struct *work)
>   			     restore_userptr_work);
>   	struct task_struct *usertask;
>   	struct mm_struct *mm;
> -	int evicted_bos;
> +	uint32_t evicted_bos;
>   
> -	evicted_bos = atomic_read(&process_info->evicted_bos);
> +	mutex_lock(&process_info->notifier_lock);
> +	evicted_bos = process_info->evicted_bos;
> +	mutex_unlock(&process_info->notifier_lock);
>   	if (!evicted_bos)
>   		return;
>   
> @@ -2516,9 +2578,6 @@ static void amdgpu_amdkfd_restore_userptr_worker(struct work_struct *work)
>   	 * and we can just restart the queues.
>   	 */
>   	if (!list_empty(&process_info->userptr_inval_list)) {
> -		if (atomic_read(&process_info->evicted_bos) != evicted_bos)
> -			goto unlock_out; /* Concurrent eviction, try again */
> -
>   		if (validate_invalid_user_pages(process_info))
>   			goto unlock_out;
>   	}
> @@ -2527,10 +2586,17 @@ static void amdgpu_amdkfd_restore_userptr_worker(struct work_struct *work)
>   	 * be a first eviction that calls quiesce_mm. The eviction
>   	 * reference counting inside KFD will handle this case.
>   	 */
> -	if (atomic_cmpxchg(&process_info->evicted_bos, evicted_bos, 0) !=
> -	    evicted_bos)
> -		goto unlock_out;
> -	evicted_bos = 0;
> +	mutex_lock(&process_info->notifier_lock);
> +	if (process_info->evicted_bos != evicted_bos)
> +		goto unlock_notifier_out;
> +
> +	if (confirm_valid_user_pages_locked(process_info)) {
> +		WARN(1, "User pages unexpectedly invalid");
> +		goto unlock_notifier_out;
> +	}
> +
> +	process_info->evicted_bos = evicted_bos = 0;
> +
>   	if (kgd2kfd_resume_mm(mm)) {
>   		pr_err("%s: Failed to resume KFD\n", __func__);
>   		/* No recovery from this failure. Probably the CP is
> @@ -2538,6 +2604,8 @@ static void amdgpu_amdkfd_restore_userptr_worker(struct work_struct *work)
>   		 */
>   	}
>   
> +unlock_notifier_out:
> +	mutex_unlock(&process_info->notifier_lock);
>   unlock_out:
>   	mutex_unlock(&process_info->lock);
>   
> diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_hmm.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_hmm.c
> index 65715cb395d8..2dadcfe43d03 100644
> --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_hmm.c
> +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_hmm.c
> @@ -105,17 +105,11 @@ static bool amdgpu_hmm_invalidate_hsa(struct mmu_interval_notifier *mni,
>   				      unsigned long cur_seq)
>   {
>   	struct amdgpu_bo *bo = container_of(mni, struct amdgpu_bo, notifier);
> -	struct amdgpu_device *adev = amdgpu_ttm_adev(bo->tbo.bdev);
>   
>   	if (!mmu_notifier_range_blockable(range))
>   		return false;
>   
> -	mutex_lock(&adev->notifier_lock);
> -
> -	mmu_interval_set_seq(mni, cur_seq);
> -
> -	amdgpu_amdkfd_evict_userptr(bo->kfd_bo, bo->notifier.mm);
> -	mutex_unlock(&adev->notifier_lock);
> +	amdgpu_amdkfd_evict_userptr(mni, cur_seq, bo->kfd_bo);
>   
>   	return true;
>   }
> @@ -244,9 +238,9 @@ int amdgpu_hmm_range_get_pages(struct mmu_interval_notifier *notifier,
>   	return r;
>   }
>   
> -int amdgpu_hmm_range_get_pages_done(struct hmm_range *hmm_range)
> +bool amdgpu_hmm_range_get_pages_done(struct hmm_range *hmm_range)
>   {
> -	int r;
> +	bool r;
>   
>   	r = mmu_interval_read_retry(hmm_range->notifier,
>   				    hmm_range->notifier_seq);
> diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_hmm.h b/drivers/gpu/drm/amd/amdgpu/amdgpu_hmm.h
> index 13ed94d3b01b..e2edcd010ccc 100644
> --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_hmm.h
> +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_hmm.h
> @@ -29,12 +29,13 @@
>   #include <linux/rwsem.h>
>   #include <linux/workqueue.h>
>   #include <linux/interval_tree.h>
> +#include <linux/mmu_notifier.h>
>   
>   int amdgpu_hmm_range_get_pages(struct mmu_interval_notifier *notifier,
>   			       uint64_t start, uint64_t npages, bool readonly,
>   			       void *owner, struct page **pages,
>   			       struct hmm_range **phmm_range);
> -int amdgpu_hmm_range_get_pages_done(struct hmm_range *hmm_range);
> +bool amdgpu_hmm_range_get_pages_done(struct hmm_range *hmm_range);
>   
>   #if defined(CONFIG_HMM_MIRROR)
>   int amdgpu_hmm_register(struct amdgpu_bo *bo, unsigned long addr);
> diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c
> index dd8b6a11db9a..5c6fabaa4444 100644
> --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c
> +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c
> @@ -703,8 +703,19 @@ int amdgpu_ttm_tt_get_user_pages(struct amdgpu_bo *bo, struct page **pages,
>   	return r;
>   }
>   
> +/* amdgpu_ttm_tt_discard_user_pages - Discard range and pfn array allocations
> + */
> +void amdgpu_ttm_tt_discard_user_pages(struct ttm_tt *ttm,
> +				      struct hmm_range *range)
> +{
> +	struct amdgpu_ttm_tt *gtt = (void *)ttm;
> +
> +	if (gtt && gtt->userptr && range)
> +		amdgpu_hmm_range_get_pages_done(range);
> +}
> +
>   /*
> - * amdgpu_ttm_tt_userptr_range_done - stop HMM track the CPU page table change
> + * amdgpu_ttm_tt_get_user_pages_done - stop HMM track the CPU page table change
>    * Check if the pages backing this ttm range have been invalidated
>    *
>    * Returns: true if pages are still valid
> @@ -722,10 +733,6 @@ bool amdgpu_ttm_tt_get_user_pages_done(struct ttm_tt *ttm,
>   
>   	WARN_ONCE(!range->hmm_pfns, "No user pages to check\n");
>   
> -	/*
> -	 * FIXME: Must always hold notifier_lock for this, and must
> -	 * not ignore the return code.
> -	 */
>   	return !amdgpu_hmm_range_get_pages_done(range);
>   }
>   #endif
> diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.h b/drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.h
> index b4d8ba2789f3..e2cd5894afc9 100644
> --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.h
> +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.h
> @@ -159,6 +159,8 @@ uint64_t amdgpu_ttm_domain_start(struct amdgpu_device *adev, uint32_t type);
>   #if IS_ENABLED(CONFIG_DRM_AMDGPU_USERPTR)
>   int amdgpu_ttm_tt_get_user_pages(struct amdgpu_bo *bo, struct page **pages,
>   				 struct hmm_range **range);
> +void amdgpu_ttm_tt_discard_user_pages(struct ttm_tt *ttm,
> +				      struct hmm_range *range);
>   bool amdgpu_ttm_tt_get_user_pages_done(struct ttm_tt *ttm,
>   				       struct hmm_range *range);
>   #else
> @@ -168,6 +170,10 @@ static inline int amdgpu_ttm_tt_get_user_pages(struct amdgpu_bo *bo,
>   {
>   	return -EPERM;
>   }
> +static inline void amdgpu_ttm_tt_discard_user_pages(struct ttm_tt *ttm,
> +						    struct hmm_range *range)
> +{
> +}
>   static inline bool amdgpu_ttm_tt_get_user_pages_done(struct ttm_tt *ttm,
>   						     struct hmm_range *range)
>   {


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