Re: [PATCH 2/2] drm/amdgpu: replace get_user_pages with HMM address mirror helpers

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On 2018-10-17 04:15 AM, Christian König wrote:
> Am 17.10.18 um 04:56 schrieb Yang, Philip:
>> Use HMM helper function hmm_vma_fault() to get physical pages backing
>> userptr and start CPU page table update track of those pages. Then use
>> hmm_vma_range_done() to check if those pages are updated before
>> amdgpu_cs_submit for gfx or before user queues are resumed for kfd.
>>
>> If userptr pages are updated, for gfx, amdgpu_cs_ioctl will restart
>> from scratch, for kfd, restore worker is rescheduled to retry.
>>
>> To avoid circular lock dependency, the locking order is:
>> mmap_sem -> amdgpu_mn_lock(p->mn) -> bo::reserve
>> mmap_sem -> bo::reserve
>
> I'm not sure that this will work, we used to have some dependencies on 
> bo::reserve -> mmap_sem.
>
> See the following patch as well:
>
> commit 2f568dbd6b944c2e8c0c54b53c2211c23995e6a4
> Author: Christian König <christian.koenig@xxxxxxx>
> Date:   Tue Feb 23 12:36:59 2016 +0100
>
>     drm/amdgpu: move get_user_pages out of amdgpu_ttm_tt_pin_userptr v6
>
>     That avoids lock inversion between the BO reservation lock
>     and the anon_vma lock.
>
> A whole bunch of more problems below.
>
Thanks for the review.

I will remove the nested lock between mmap_sem and bo::reserve, and 
change the kfd side locking order
to bo::reserve -> amdgpu_mn_lock(p->mn) as the original gfx side locking 
order.

Will submit patch v2 with other changes.

Philip
>>
>> HMM simplify the CPU page table concurrently update check, so remove
>> guptasklock, mmu_invalidations, last_set_pages fields from
>> amdgpu_ttm_tt struct.
>>
>> HMM doesnot pin the page (increase page ref count), so remove related
>> operations like release_pages(), put_page(), mark_page_dirty().
>>
>> Change-Id: Iffd5f855cc9ce402cdfca167f68f83fe39ac56f9
>> Signed-off-by: Philip Yang <Philip.Yang@xxxxxxx>
>> ---
>>   drivers/gpu/drm/amd/amdgpu/amdgpu_amdkfd_gpuvm.c | 101 ++++++++++---
>>   drivers/gpu/drm/amd/amdgpu/amdgpu_bo_list.c      |   2 -
>>   drivers/gpu/drm/amd/amdgpu/amdgpu_bo_list.h      |   3 +-
>>   drivers/gpu/drm/amd/amdgpu/amdgpu_cs.c           | 171 
>> +++++++++--------------
>>   drivers/gpu/drm/amd/amdgpu/amdgpu_gem.c          |  14 +-
>>   drivers/gpu/drm/amd/amdgpu/amdgpu_mn.c           |  34 ++++-
>>   drivers/gpu/drm/amd/amdgpu/amdgpu_mn.h           |   7 +-
>>   drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c          | 164 
>> +++++++++-------------
>>   drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.h          |   3 +-
>>   drivers/gpu/drm/amd/amdgpu/amdgpu_vm.c           |   1 -
>>   10 files changed, 252 insertions(+), 248 deletions(-)
>>
>> diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_amdkfd_gpuvm.c 
>> b/drivers/gpu/drm/amd/amdgpu/amdgpu_amdkfd_gpuvm.c
>> index df0a059..3fd0340 100644
>> --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_amdkfd_gpuvm.c
>> +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_amdkfd_gpuvm.c
>> @@ -615,8 +615,7 @@ static int init_user_pages(struct kgd_mem *mem, 
>> struct mm_struct *mm,
>>       amdgpu_bo_unreserve(bo);
>>     release_out:
>> -    if (ret)
>> -        release_pages(mem->user_pages, bo->tbo.ttm->num_pages);
>> +    amdgpu_ttm_tt_get_user_pages_done(bo->tbo.ttm);
>>   free_out:
>>       kvfree(mem->user_pages);
>>       mem->user_pages = NULL;
>> @@ -678,7 +677,6 @@ static int reserve_bo_and_vm(struct kgd_mem *mem,
>>       ctx->kfd_bo.priority = 0;
>>       ctx->kfd_bo.tv.bo = &bo->tbo;
>>       ctx->kfd_bo.tv.shared = true;
>> -    ctx->kfd_bo.user_pages = NULL;
>>       list_add(&ctx->kfd_bo.tv.head, &ctx->list);
>>         amdgpu_vm_get_pd_bo(vm, &ctx->list, &ctx->vm_pd[0]);
>> @@ -742,7 +740,6 @@ static int reserve_bo_and_cond_vms(struct kgd_mem 
>> *mem,
>>       ctx->kfd_bo.priority = 0;
>>       ctx->kfd_bo.tv.bo = &bo->tbo;
>>       ctx->kfd_bo.tv.shared = true;
>> -    ctx->kfd_bo.user_pages = NULL;
>>       list_add(&ctx->kfd_bo.tv.head, &ctx->list);
>>         i = 0;
>> @@ -1311,9 +1308,6 @@ int amdgpu_amdkfd_gpuvm_free_memory_of_gpu(
>>       /* Free user pages if necessary */
>>       if (mem->user_pages) {
>>           pr_debug("%s: Freeing user_pages array\n", __func__);
>> -        if (mem->user_pages[0])
>> -            release_pages(mem->user_pages,
>> -                    mem->bo->tbo.ttm->num_pages);
>>           kvfree(mem->user_pages);
>>       }
>>   @@ -1739,8 +1733,6 @@ static int update_invalid_user_pages(struct 
>> amdkfd_process_info *process_info,
>>                          __func__);
>>                   return -ENOMEM;
>>               }
>> -        } else if (mem->user_pages[0]) {
>> -            release_pages(mem->user_pages, bo->tbo.ttm->num_pages);
>>           }
>>             /* Get updated user pages */
>> @@ -1756,12 +1748,6 @@ static int update_invalid_user_pages(struct 
>> amdkfd_process_info *process_info,
>>                * stalled user mode queues.
>>                */
>>           }
>> -
>> -        /* Mark the BO as valid unless it was invalidated
>> -         * again concurrently
>> -         */
>> -        if (atomic_cmpxchg(&mem->invalid, invalid, 0) != invalid)
>> -            return -EAGAIN;
>>       }
>>         return 0;
>> @@ -1854,14 +1840,10 @@ static int validate_invalid_user_pages(struct 
>> amdkfd_process_info *process_info)
>>           }
>>             /* Validate succeeded, now the BO owns the pages, free
>> -         * our copy of the pointer array. Put this BO back on
>> -         * the userptr_valid_list. If we need to revalidate
>> -         * it, we need to start from scratch.
>> +         * our copy of the pointer array.
>>            */
>>           kvfree(mem->user_pages);
>>           mem->user_pages = NULL;
>> -        list_move_tail(&mem->validate_list.head,
>> -                   &process_info->userptr_valid_list);
>
> I'm not an expert on the KFD stuff, but that doesn't looks correct to me.
>
>>             /* Update mapping. If the BO was not validated
>>            * (because we couldn't get user pages), this will
>> @@ -1902,6 +1884,70 @@ static int validate_invalid_user_pages(struct 
>> amdkfd_process_info *process_info)
>>       return ret;
>>   }
>>   +/* user_pages_invalidated - if CPU page table is updated after 
>> getting user
>> + * pages
>> + *
>> + * HMM mirror callback lock amn is hold to prevent the concurrent CPU
>> + * page table update while resuming user queues.
>> + *
>> + * Returns: true if CPU page table is updated, false otherwise
>> + */
>> +static int user_pages_invalidated(struct mm_struct *mm,
>> +            struct amdkfd_process_info *process_info,
>> +            struct amdgpu_mn **amn)
>> +{
>> +    struct kgd_mem *mem, *tmp_mem;
>> +    struct amdgpu_bo *bo;
>> +    struct amdgpu_device *adev;
>> +    int invalid, r = 0;
>> +
>> +    list_for_each_entry_safe(mem, tmp_mem,
>> +                 &process_info->userptr_inval_list,
>> +                 validate_list.head) {
>> +
>> +        invalid = atomic_read(&mem->invalid);
>> +        if (!invalid)
>> +            /* BO hasn't been invalidated since the last
>> +             * revalidation attempt. Keep its BO list.
>> +             */
>> +            continue;
>> +
>> +        bo = mem->bo;
>> +
>> +        /* Get HMM mirror callback lock */
>> +        if (!*amn) {
>> +            adev = amdgpu_ttm_adev(bo->tbo.bdev);
>> +            *amn = amdgpu_mn_get(mm, adev, AMDGPU_MN_TYPE_HSA);
>> +            if (IS_ERR(*amn)) {
>> +                r = true;
>> +                *amn = NULL;
>> +                goto out;
>> +            }
>> +
>> +            amdgpu_mn_lock(*amn);
>> +        }
>> +
>> +        r |= amdgpu_ttm_tt_get_user_pages_done(bo->tbo.ttm);
>> +
>> +        /* Put this BO back on the userptr_valid_list. If we need to
>> +         * revalidate it, we need to start from scratch.
>> +         */
>> +        list_move_tail(&mem->validate_list.head,
>> +                   &process_info->userptr_valid_list);
>> +
>> +        /* Mark the BO as valid unless it was invalidated
>> +         * again concurrently
>> +         */
>> +        if (atomic_cmpxchg(&mem->invalid, invalid, 0) != invalid) {
>> +            r = true;
>> +            goto out;
>> +        }
>> +    }
>> +
>> +out:
>> +    return r;
>> +}
>> +
>>   /* Worker callback to restore evicted userptr BOs
>>    *
>>    * Tries to update and validate all userptr BOs. If successful and no
>> @@ -1917,6 +1963,7 @@ static void 
>> amdgpu_amdkfd_restore_userptr_worker(struct work_struct *work)
>>       struct task_struct *usertask;
>>       struct mm_struct *mm;
>>       int evicted_bos;
>> +    struct amdgpu_mn *amn = NULL;
>>         evicted_bos = atomic_read(&process_info->evicted_bos);
>>       if (!evicted_bos)
>> @@ -1955,13 +2002,27 @@ static void 
>> amdgpu_amdkfd_restore_userptr_worker(struct work_struct *work)
>>       if (atomic_cmpxchg(&process_info->evicted_bos, evicted_bos, 0) !=
>>           evicted_bos)
>>           goto unlock_out;
>> +
>> +    /* If CPU page table is updated again after getting user pages,
>> +     * schedule to restart the restore process again.
>> +     *
>> +     * amn is also locked to prevent CPU page table update while 
>> resuming
>> +     * user queues. amn is unlocked after user queues are resumed.
>> +     */
>> +    if (user_pages_invalidated(mm, process_info, &amn))
>> +        goto unlock_mn_out;
>> +
>>       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
>>            * hanging. No point trying again.
>>            */
>>       }
>> +
>> +unlock_mn_out:
>> +    amdgpu_mn_unlock(amn);
>>   unlock_out:
>>       mutex_unlock(&process_info->lock);
>>       mmput(mm);
>> diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_bo_list.c 
>> b/drivers/gpu/drm/amd/amdgpu/amdgpu_bo_list.c
>> index 14d2982..2716c24 100644
>> --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_bo_list.c
>> +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_bo_list.c
>> @@ -201,8 +201,6 @@ void amdgpu_bo_list_get_list(struct 
>> amdgpu_bo_list *list,
>>             if (!bo->parent)
>>               list_add_tail(&e->tv.head, &bucket[priority]);
>> -
>> -        e->user_pages = NULL;
>>       }
>>         /* Connect the sorted buckets in the output list. */
>> diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_bo_list.h 
>> b/drivers/gpu/drm/amd/amdgpu/amdgpu_bo_list.h
>> index 7c5f5d1..4beab2d 100644
>> --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_bo_list.h
>> +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_bo_list.h
>> @@ -35,8 +35,7 @@ struct amdgpu_bo_list_entry {
>>       struct ttm_validate_buffer    tv;
>>       struct amdgpu_bo_va        *bo_va;
>>       uint32_t            priority;
>> -    struct page            **user_pages;
>> -    int                user_invalidated;
>> +    bool                user_invalidated;
>>   };
>>     struct amdgpu_bo_list {
>> diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_cs.c 
>> b/drivers/gpu/drm/amd/amdgpu/amdgpu_cs.c
>> index 8836186..c46af18 100644
>> --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_cs.c
>> +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_cs.c
>> @@ -51,7 +51,6 @@ static int amdgpu_cs_user_fence_chunk(struct 
>> amdgpu_cs_parser *p,
>>       p->uf_entry.priority = 0;
>>       p->uf_entry.tv.bo = &bo->tbo;
>>       p->uf_entry.tv.shared = true;
>> -    p->uf_entry.user_pages = NULL;
>>         drm_gem_object_put_unlocked(gobj);
>>   @@ -531,24 +530,19 @@ static int amdgpu_cs_list_validate(struct 
>> amdgpu_cs_parser *p,
>>         list_for_each_entry(lobj, validated, tv.head) {
>>           struct amdgpu_bo *bo = ttm_to_amdgpu_bo(lobj->tv.bo);
>> -        bool binding_userptr = false;
>>           struct mm_struct *usermm;
>>             usermm = amdgpu_ttm_tt_get_usermm(bo->tbo.ttm);
>>           if (usermm && usermm != current->mm)
>>               return -EPERM;
>>   -        /* Check if we have user pages and nobody bound the BO 
>> already */
>> -        if (amdgpu_ttm_tt_userptr_needs_pages(bo->tbo.ttm) &&
>> -            lobj->user_pages) {
>> +        if (amdgpu_ttm_tt_is_userptr(bo->tbo.ttm) &&
>> +            lobj->user_invalidated) {
>>               amdgpu_bo_placement_from_domain(bo,
>>                               AMDGPU_GEM_DOMAIN_CPU);
>>               r = ttm_bo_validate(&bo->tbo, &bo->placement, &ctx);
>>               if (r)
>>                   return r;
>> -            amdgpu_ttm_tt_set_user_pages(bo->tbo.ttm,
>> -                             lobj->user_pages);
>> -            binding_userptr = true;
>>           }
>>             if (p->evictable == lobj)
>> @@ -557,11 +551,6 @@ static int amdgpu_cs_list_validate(struct 
>> amdgpu_cs_parser *p,
>>           r = amdgpu_cs_validate(p, bo);
>>           if (r)
>>               return r;
>> -
>> -        if (binding_userptr) {
>> -            kvfree(lobj->user_pages);
>> -            lobj->user_pages = NULL;
>> -        }
>>       }
>>       return 0;
>>   }
>> @@ -576,7 +565,6 @@ static int amdgpu_cs_parser_bos(struct 
>> amdgpu_cs_parser *p,
>>       struct amdgpu_bo *gds;
>>       struct amdgpu_bo *gws;
>>       struct amdgpu_bo *oa;
>> -    unsigned tries = 10;
>>       int r;
>>         INIT_LIST_HEAD(&p->validated);
>> @@ -585,7 +573,6 @@ static int amdgpu_cs_parser_bos(struct 
>> amdgpu_cs_parser *p,
>>       if (cs->in.bo_list_handle) {
>>           if (p->bo_list)
>>               return -EINVAL;
>> -
>>           r = amdgpu_bo_list_get(fpriv, cs->in.bo_list_handle,
>>                          &p->bo_list);
>>           if (r)
>> @@ -599,8 +586,10 @@ static int amdgpu_cs_parser_bos(struct 
>> amdgpu_cs_parser *p,
>>       }
>>         amdgpu_bo_list_get_list(p->bo_list, &p->validated);
>> -    if (p->bo_list->first_userptr != p->bo_list->num_entries)
>> -        p->mn = amdgpu_mn_get(p->adev, AMDGPU_MN_TYPE_GFX);
>> +    if (p->bo_list->first_userptr != p->bo_list->num_entries) {
>> +        p->mn = amdgpu_mn_get(current->mm, p->adev,
>> +                    AMDGPU_MN_TYPE_GFX);
>> +    }
>
> Please don't add {} here.
>
>>         INIT_LIST_HEAD(&duplicates);
>>       amdgpu_vm_get_pd_bo(&fpriv->vm, &p->validated, &p->vm_pd);
>> @@ -608,79 +597,41 @@ static int amdgpu_cs_parser_bos(struct 
>> amdgpu_cs_parser *p,
>>       if (p->uf_entry.tv.bo && 
>> !ttm_to_amdgpu_bo(p->uf_entry.tv.bo)->parent)
>>           list_add(&p->uf_entry.tv.head, &p->validated);
>>   -    while (1) {
>> -        struct list_head need_pages;
>> -
>> -        r = ttm_eu_reserve_buffers(&p->ticket, &p->validated, true,
>> -                       &duplicates);
>> -        if (unlikely(r != 0)) {
>> -            if (r != -ERESTARTSYS)
>> -                DRM_ERROR("ttm_eu_reserve_buffers failed.\n");
>> -            goto error_free_pages;
>> -        }
>> -
>> -        INIT_LIST_HEAD(&need_pages);
>> -        amdgpu_bo_list_for_each_userptr_entry(e, p->bo_list) {
>> -            struct amdgpu_bo *bo = ttm_to_amdgpu_bo(e->tv.bo);
>> -
>> -            if (amdgpu_ttm_tt_userptr_invalidated(bo->tbo.ttm,
>> -                 &e->user_invalidated) && e->user_pages) {
>> -
>> -                /* We acquired a page array, but somebody
>> -                 * invalidated it. Free it and try again
>> -                 */
>> -                release_pages(e->user_pages,
>> -                          bo->tbo.ttm->num_pages);
>> -                kvfree(e->user_pages);
>> -                e->user_pages = NULL;
>> -            }
>> +    /* Get userptr backing pages. If pages are updated after registered
>> +     * in amdgpu_gem_userptr_ioctl(), amdgpu_cs_list_validate() will do
>> +     * amdgpu_ttm_backend_bind() to flush and invalidate new pages
>> +     */
>> +    amdgpu_bo_list_for_each_userptr_entry(e, p->bo_list) {
>> +        struct amdgpu_bo *bo = ttm_to_amdgpu_bo(e->tv.bo);
>> +        struct page *user_pages[bo->tbo.ttm->num_pages];
>
> Dynamic allocation of arrays on the stack is illegal in the kernel.
Will change to kvmalloc_array and kvfree because we don't know the max 
userptr pages.
You are right, it's bad idea to use VLA in kernel.
>
>> +        int i;
>> +        bool user_invalidated = false;
>>   -            if (amdgpu_ttm_tt_userptr_needs_pages(bo->tbo.ttm) &&
>> -                !e->user_pages) {
>> -                list_del(&e->tv.head);
>> -                list_add(&e->tv.head, &need_pages);
>> +        r = amdgpu_ttm_tt_get_user_pages(bo->tbo.ttm, user_pages);
>> +        if (r)
>> +            return r;
>>   -                amdgpu_bo_unreserve(bo);
>> +        for (i = 0; i < bo->tbo.ttm->num_pages; i++) {
>> +            if (bo->tbo.ttm->pages[i] != user_pages[i]) {
>> +                bo->tbo.ttm->pages[i] = user_pages[i];
>> +                user_invalidated = true;
>
> The BO is not reserved, isn't it? So that is not protected by any locks?
>
>>               }
>>           }
>> +        e->user_invalidated = user_invalidated;
>> +    }
>>   -        if (list_empty(&need_pages))
>> -            break;
>> -
>> -        /* Unreserve everything again. */
>> -        ttm_eu_backoff_reservation(&p->ticket, &p->validated);
>> -
>> -        /* We tried too many times, just abort */
>> -        if (!--tries) {
>> -            r = -EDEADLK;
>> -            DRM_ERROR("deadlock in %s\n", __func__);
>> -            goto error_free_pages;
>> -        }
>> -
>> -        /* Fill the page arrays for all userptrs. */
>> -        list_for_each_entry(e, &need_pages, tv.head) {
>> -            struct ttm_tt *ttm = e->tv.bo->ttm;
>> -
>> -            e->user_pages = kvmalloc_array(ttm->num_pages,
>> -                             sizeof(struct page*),
>> -                             GFP_KERNEL | __GFP_ZERO);
>> -            if (!e->user_pages) {
>> -                r = -ENOMEM;
>> -                DRM_ERROR("calloc failure in %s\n", __func__);
>> -                goto error_free_pages;
>> -            }
>> -
>> -            r = amdgpu_ttm_tt_get_user_pages(ttm, e->user_pages);
>> -            if (r) {
>> -                DRM_ERROR("amdgpu_ttm_tt_get_user_pages failed.\n");
>> -                kvfree(e->user_pages);
>> -                e->user_pages = NULL;
>> -                goto error_free_pages;
>> -            }
>> -        }
>> +    /* No memory allocation is allowed while holding the mn lock.
>> +     * p->mn is hold until amdgpu_cs_submit is finished and fence is 
>> added
>> +     * to BOs.
>> +     */
>> +    amdgpu_mn_lock(p->mn);
>
> That won't work. We allocate tons of memory after this point during BO 
> validation.
>
> Christian.
>
>>   -        /* And try again. */
>> -        list_splice(&need_pages, &p->validated);
>> +    r = ttm_eu_reserve_buffers(&p->ticket, &p->validated, true,
>> +                   &duplicates);
>> +    if (unlikely(r != 0)) {
>> +        if (r != -ERESTARTSYS)
>> +            DRM_ERROR("ttm_eu_reserve_buffers failed.\n");
>> +        goto out;
>>       }
>>         amdgpu_cs_get_threshold_for_moves(p->adev, 
>> &p->bytes_moved_threshold,
>> @@ -743,16 +694,9 @@ static int amdgpu_cs_parser_bos(struct 
>> amdgpu_cs_parser *p,
>>   error_validate:
>>       if (r)
>>           ttm_eu_backoff_reservation(&p->ticket, &p->validated);
>> -
>> -error_free_pages:
>> -
>> -    amdgpu_bo_list_for_each_userptr_entry(e, p->bo_list) {
>> -        if (!e->user_pages)
>> -            continue;
>> -
>> -        release_pages(e->user_pages, e->tv.bo->ttm->num_pages);
>> -        kvfree(e->user_pages);
>> -    }
>> +out:
>> +    if (r)
>> +        amdgpu_mn_unlock(p->mn);
>>         return r;
>>   }
>> @@ -1206,8 +1150,7 @@ static int amdgpu_cs_submit(struct 
>> amdgpu_cs_parser *p,
>>       struct amdgpu_bo_list_entry *e;
>>       struct amdgpu_job *job;
>>       uint64_t seq;
>> -
>> -    int r;
>> +    int r = 0;
>>         job = p->job;
>>       p->job = NULL;
>> @@ -1216,15 +1159,18 @@ static int amdgpu_cs_submit(struct 
>> amdgpu_cs_parser *p,
>>       if (r)
>>           goto error_unlock;
>>   -    /* No memory allocation is allowed while holding the mn lock */
>> -    amdgpu_mn_lock(p->mn);
>> +    /* If userptr are updated after amdgpu_cs_parser_bos(), restart 
>> cs */
>>       amdgpu_bo_list_for_each_userptr_entry(e, p->bo_list) {
>>           struct amdgpu_bo *bo = ttm_to_amdgpu_bo(e->tv.bo);
>>   -        if (amdgpu_ttm_tt_userptr_needs_pages(bo->tbo.ttm)) {
>> -            r = -ERESTARTSYS;
>> -            goto error_abort;
>> -        }
>> +        e->user_invalidated =
>> + amdgpu_ttm_tt_get_user_pages_done(bo->tbo.ttm);
>> +
>> +        r |= e->user_invalidated;
>> +    }
>> +    if (r) {
>> +        r = -ERESTARTSYS;
>> +        goto error_abort;
>>       }
>>         job->owner = p->filp;
>> @@ -1272,14 +1218,20 @@ static int amdgpu_cs_submit(struct 
>> amdgpu_cs_parser *p,
>>   int amdgpu_cs_ioctl(struct drm_device *dev, void *data, struct 
>> drm_file *filp)
>>   {
>>       struct amdgpu_device *adev = dev->dev_private;
>> -    union drm_amdgpu_cs *cs = data;
>> -    struct amdgpu_cs_parser parser = {};
>> -    bool reserved_buffers = false;
>> +    union drm_amdgpu_cs *cs;
>> +    struct amdgpu_cs_parser parser;
>> +    bool reserved_buffers;
>> +    int tries = 10;
>>       int i, r;
>>         if (!adev->accel_working)
>>           return -EBUSY;
>>   +restart:
>> +    memset(&parser, 0, sizeof(parser));
>> +    cs = data;
>> +    reserved_buffers = false;
>> +
>>       parser.adev = adev;
>>       parser.filp = filp;
>>   @@ -1321,6 +1273,15 @@ int amdgpu_cs_ioctl(struct drm_device *dev, 
>> void *data, struct drm_file *filp)
>>     out:
>>       amdgpu_cs_parser_fini(&parser, r, reserved_buffers);
>> +
>> +    if (r == -ERESTARTSYS) {
>> +        if (!--tries) {
>> +            DRM_ERROR("Possible deadlock? Retry too many times\n");
>> +            return -EDEADLK;
>> +        }
>> +        goto restart;
>> +    }
>> +
>>       return r;
>>   }
>>   diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_gem.c 
>> b/drivers/gpu/drm/amd/amdgpu/amdgpu_gem.c
>> index 7b3d1eb..ff9a8fd 100644
>> --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_gem.c
>> +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_gem.c
>> @@ -336,26 +336,24 @@ int amdgpu_gem_userptr_ioctl(struct drm_device 
>> *dev, void *data,
>>             r = amdgpu_bo_reserve(bo, true);
>>           if (r)
>> -            goto free_pages;
>> +            goto user_pages_done;
>>             amdgpu_bo_placement_from_domain(bo, AMDGPU_GEM_DOMAIN_GTT);
>>           r = ttm_bo_validate(&bo->tbo, &bo->placement, &ctx);
>>           amdgpu_bo_unreserve(bo);
>>           if (r)
>> -            goto free_pages;
>> +            goto user_pages_done;
>>       }
>>         r = drm_gem_handle_create(filp, gobj, &handle);
>> -    /* drop reference from allocate - handle holds it now */
>> -    drm_gem_object_put_unlocked(gobj);
>>       if (r)
>> -        return r;
>> +        goto user_pages_done;
>>         args->handle = handle;
>> -    return 0;
>>   -free_pages:
>> -    release_pages(bo->tbo.ttm->pages, bo->tbo.ttm->num_pages);
>> +user_pages_done:
>> +    if (args->flags & AMDGPU_GEM_USERPTR_VALIDATE)
>> +        amdgpu_ttm_tt_get_user_pages_done(bo->tbo.ttm);
>>     release_object:
>>       drm_gem_object_put_unlocked(gobj);
>> diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_mn.c 
>> b/drivers/gpu/drm/amd/amdgpu/amdgpu_mn.c
>> index 56595b3..6b6becd 100644
>> --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_mn.c
>> +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_mn.c
>> @@ -229,8 +229,6 @@ static void amdgpu_mn_invalidate_node(struct 
>> amdgpu_mn_node *node,
>>               true, false, MAX_SCHEDULE_TIMEOUT);
>>           if (r <= 0)
>>               DRM_ERROR("(%ld) failed to wait for user bo\n", r);
>> -
>> -        amdgpu_ttm_tt_mark_user_pages(bo->tbo.ttm);
>>       }
>>   }
>>   @@ -355,15 +353,16 @@ static struct hmm_mirror_ops 
>> amdgpu_hmm_mirror_ops[] = {
>>   /**
>>    * amdgpu_mn_get - create HMM mirror context
>>    *
>> + * @mm: the mm struct
>>    * @adev: amdgpu device pointer
>>    * @type: type of MMU notifier context
>>    *
>> - * Creates a HMM mirror context for current->mm.
>> + * Creates a HMM mirror context for mm.
>>    */
>> -struct amdgpu_mn *amdgpu_mn_get(struct amdgpu_device *adev,
>> +struct amdgpu_mn *amdgpu_mn_get(struct mm_struct *mm,
>> +                struct amdgpu_device *adev,
>>                   enum amdgpu_mn_type type)
>>   {
>> -    struct mm_struct *mm = current->mm;
>>       struct amdgpu_mn *amn;
>>       unsigned long key = AMDGPU_MN_KEY(mm, type);
>>       int r;
>> @@ -433,7 +432,7 @@ int amdgpu_mn_register(struct amdgpu_bo *bo, 
>> unsigned long addr)
>>       struct list_head bos;
>>       struct interval_tree_node *it;
>>   -    amn = amdgpu_mn_get(adev, type);
>> +    amn = amdgpu_mn_get(current->mm, adev, type);
>>       if (IS_ERR(amn))
>>           return PTR_ERR(amn);
>>   @@ -515,3 +514,26 @@ void amdgpu_mn_unregister(struct amdgpu_bo *bo)
>>       mutex_unlock(&adev->mn_lock);
>>   }
>>   +/* flags used by HMM internal, not related to CPU/GPU PTE flags */
>> +static const uint64_t hmm_range_flags[HMM_PFN_FLAG_MAX] = {
>> +        (1 << 0), /* HMM_PFN_VALID */
>> +        (1 << 1), /* HMM_PFN_WRITE */
>> +        0 /* HMM_PFN_DEVICE_PRIVATE */
>> +};
>> +
>> +static const uint64_t hmm_range_values[HMM_PFN_VALUE_MAX] = {
>> +        0xfffffffffffffffeUL, /* HMM_PFN_ERROR */
>> +        0, /* HMM_PFN_NONE */
>> +        0xfffffffffffffffcUL /* HMM_PFN_SPECIAL */
>> +};
>> +
>> +void amdgpu_hmm_init_range(struct hmm_range *range)
>> +{
>> +    if (range) {
>> +        range->flags = hmm_range_flags;
>> +        range->values = hmm_range_values;
>> +        range->pfn_shift = PAGE_SHIFT;
>> +        range->pfns = NULL;
>> +        INIT_LIST_HEAD(&range->list);
>> +    }
>> +}
>> diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_mn.h 
>> b/drivers/gpu/drm/amd/amdgpu/amdgpu_mn.h
>> index 0e27526..59ea30e 100644
>> --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_mn.h
>> +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_mn.h
>> @@ -25,9 +25,10 @@
>>   #define __AMDGPU_MN_H__
>>     /*
>> - * MMU Notifier
>> + * HMM mirror
>>    */
>>   struct amdgpu_mn;
>> +struct hmm_range;
>>     enum amdgpu_mn_type {
>>       AMDGPU_MN_TYPE_GFX,
>> @@ -37,10 +38,12 @@ enum amdgpu_mn_type {
>>   #if defined(CONFIG_HMM)
>>   void amdgpu_mn_lock(struct amdgpu_mn *mn);
>>   void amdgpu_mn_unlock(struct amdgpu_mn *mn);
>> -struct amdgpu_mn *amdgpu_mn_get(struct amdgpu_device *adev,
>> +struct amdgpu_mn *amdgpu_mn_get(struct mm_struct *mm,
>> +                struct amdgpu_device *adev,
>>                   enum amdgpu_mn_type type);
>>   int amdgpu_mn_register(struct amdgpu_bo *bo, unsigned long addr);
>>   void amdgpu_mn_unregister(struct amdgpu_bo *bo);
>> +void amdgpu_hmm_init_range(struct hmm_range *range);
>>   #else
>>   static inline void amdgpu_mn_lock(struct amdgpu_mn *mn) {}
>>   static inline void amdgpu_mn_unlock(struct amdgpu_mn *mn) {}
>> diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c 
>> b/drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c
>> index 3a68028..b0537d1 100644
>> --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c
>> +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c
>> @@ -43,6 +43,7 @@
>>   #include <linux/pagemap.h>
>>   #include <linux/debugfs.h>
>>   #include <linux/iommu.h>
>> +#include <linux/hmm.h>
>>   #include "amdgpu.h"
>>   #include "amdgpu_object.h"
>>   #include "amdgpu_trace.h"
>> @@ -799,11 +800,6 @@ static unsigned long 
>> amdgpu_ttm_io_mem_pfn(struct ttm_buffer_object *bo,
>>   /*
>>    * TTM backend functions.
>>    */
>> -struct amdgpu_ttm_gup_task_list {
>> -    struct list_head    list;
>> -    struct task_struct    *task;
>> -};
>> -
>>   struct amdgpu_ttm_tt {
>>       struct ttm_dma_tt    ttm;
>>       u64            offset;
>> @@ -812,85 +808,91 @@ struct amdgpu_ttm_tt {
>>       uint32_t        userflags;
>>       spinlock_t              guptasklock;
>>       struct list_head        guptasks;
>> -    atomic_t        mmu_invalidations;
>> -    uint32_t        last_set_pages;
>> +    struct hmm_range    range;
>>   };
>>     /**
>> - * amdgpu_ttm_tt_get_user_pages - Pin pages of memory pointed to by 
>> a USERPTR
>> - * pointer to memory
>> + * amdgpu_ttm_tt_get_user_pages - get device accessible pages that 
>> back user
>> + * memory and start HMM tracking CPU page table update
>>    *
>> - * Called by amdgpu_gem_userptr_ioctl() and amdgpu_cs_parser_bos().
>> - * This provides a wrapper around the get_user_pages() call to provide
>> - * device accessible pages that back user memory.
>> + * Calling function must call amdgpu_ttm_tt_userptr_range_done() 
>> once and only
>> + * once afterwards to stop HMM tracking
>>    */
>>   int amdgpu_ttm_tt_get_user_pages(struct ttm_tt *ttm, struct page 
>> **pages)
>>   {
>>       struct amdgpu_ttm_tt *gtt = (void *)ttm;
>>       struct mm_struct *mm = gtt->usertask->mm;
>> -    unsigned int flags = 0;
>> -    unsigned pinned = 0;
>> -    int r;
>> +    unsigned long end = gtt->userptr + ttm->num_pages * PAGE_SIZE;
>> +    struct hmm_range *range = &gtt->range;
>> +    int r, i;
>>         if (!mm) /* Happens during process shutdown */
>>           return -ESRCH;
>>   -    if (!(gtt->userflags & AMDGPU_GEM_USERPTR_READONLY))
>> -        flags |= FOLL_WRITE;
>> +    amdgpu_hmm_init_range(range);
>>         down_read(&mm->mmap_sem);
>>   -    if (gtt->userflags & AMDGPU_GEM_USERPTR_ANONONLY) {
>> -        /*
>> -         * check that we only use anonymous memory to prevent problems
>> -         * with writeback
>> -         */
>> -        unsigned long end = gtt->userptr + ttm->num_pages * PAGE_SIZE;
>> -        struct vm_area_struct *vma;
>> +    range->vma = find_vma(mm, gtt->userptr);
>> +    if (!range->vma || range->vma->vm_file || range->vma->vm_end < 
>> end) {
>> +        r = -EPERM;
>> +        goto out;
>> +    }
>> +    range->pfns = kvmalloc_array(ttm->num_pages, sizeof(uint64_t),
>> +                GFP_KERNEL | __GFP_ZERO);
>> +    if (range->pfns == NULL) {
>> +        r = -ENOMEM;
>> +        goto out;
>> +    }
>> +    range->start = gtt->userptr;
>> +    range->end = end;
>>   -        vma = find_vma(mm, gtt->userptr);
>> -        if (!vma || vma->vm_file || vma->vm_end < end) {
>> -            up_read(&mm->mmap_sem);
>> -            return -EPERM;
>> -        }
>> +    for (i = 0; i < ttm->num_pages; i++) {
>> +        range->pfns[i] = range->flags[HMM_PFN_VALID];
>> +        range->pfns[i] |= amdgpu_ttm_tt_is_readonly(ttm) ?
>> +                    0 : range->flags[HMM_PFN_WRITE];
>>       }
>>   -    /* loop enough times using contiguous pages of memory */
>> -    do {
>> -        unsigned num_pages = ttm->num_pages - pinned;
>> -        uint64_t userptr = gtt->userptr + pinned * PAGE_SIZE;
>> -        struct page **p = pages + pinned;
>> -        struct amdgpu_ttm_gup_task_list guptask;
>> +    /* This may triggles page table update */
>> +    r = hmm_vma_fault(range, true);
>> +    if (r)
>> +        goto out_free_pfns;
>>   -        guptask.task = current;
>> -        spin_lock(&gtt->guptasklock);
>> -        list_add(&guptask.list, &gtt->guptasks);
>> -        spin_unlock(&gtt->guptasklock);
>> +    for (i = 0; i < ttm->num_pages; i++)
>> +        pages[i] = hmm_pfn_to_page(range, range->pfns[i]);
>>   -        if (mm == current->mm)
>> -            r = get_user_pages(userptr, num_pages, flags, p, NULL);
>> -        else
>> -            r = get_user_pages_remote(gtt->usertask,
>> -                    mm, userptr, num_pages,
>> -                    flags, p, NULL, NULL);
>> +    up_read(&mm->mmap_sem);
>> +    return 0;
>>   -        spin_lock(&gtt->guptasklock);
>> -        list_del(&guptask.list);
>> -        spin_unlock(&gtt->guptasklock);
>> +out_free_pfns:
>> +    kvfree(range->pfns);
>> +    range->pfns = NULL;
>> +out:
>> +    up_read(&mm->mmap_sem);
>> +    return r;
>> +}
>>   -        if (r < 0)
>> -            goto release_pages;
>> +/**
>> + * amdgpu_ttm_tt_userptr_range_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 invalidated since the last time 
>> they've been set
>> + */
>> +bool amdgpu_ttm_tt_get_user_pages_done(struct ttm_tt *ttm)
>> +{
>> +    struct amdgpu_ttm_tt *gtt = (void *)ttm;
>> +    int r;
>>   -        pinned += r;
>> +    if (gtt == NULL || !gtt->userptr)
>> +        return false;
>>   -    } while (pinned < ttm->num_pages);
>> +    r = !hmm_vma_range_done(&gtt->range);
>>   -    up_read(&mm->mmap_sem);
>> -    return 0;
>> +    if (gtt->range.pfns) {
>> +        kvfree(gtt->range.pfns);
>> +        gtt->range.pfns = NULL;
>> +    }
>>   -release_pages:
>> -    release_pages(pages, pinned);
>> -    up_read(&mm->mmap_sem);
>>       return r;
>>   }
>>   @@ -903,16 +905,10 @@ int amdgpu_ttm_tt_get_user_pages(struct 
>> ttm_tt *ttm, struct page **pages)
>>    */
>>   void amdgpu_ttm_tt_set_user_pages(struct ttm_tt *ttm, struct page 
>> **pages)
>>   {
>> -    struct amdgpu_ttm_tt *gtt = (void *)ttm;
>>       unsigned i;
>>   -    gtt->last_set_pages = atomic_read(&gtt->mmu_invalidations);
>> -    for (i = 0; i < ttm->num_pages; ++i) {
>> -        if (ttm->pages[i])
>> -            put_page(ttm->pages[i]);
>> -
>> +    for (i = 0; i < ttm->num_pages; ++i)
>>           ttm->pages[i] = pages ? pages[i] : NULL;
>> -    }
>>   }
>>     /**
>> @@ -997,9 +993,6 @@ static void amdgpu_ttm_tt_unpin_userptr(struct 
>> ttm_tt *ttm)
>>       /* unmap the pages mapped to the device */
>>       dma_unmap_sg(adev->dev, ttm->sg->sgl, ttm->sg->nents, direction);
>>   -    /* mark the pages as dirty */
>> -    amdgpu_ttm_tt_mark_user_pages(ttm);
>> -
>>       sg_free_table(ttm->sg);
>>   }
>>   @@ -1352,8 +1345,6 @@ int amdgpu_ttm_tt_set_userptr(struct ttm_tt 
>> *ttm, uint64_t addr,
>>         spin_lock_init(&gtt->guptasklock);
>>       INIT_LIST_HEAD(&gtt->guptasks);
>> -    atomic_set(&gtt->mmu_invalidations, 0);
>> -    gtt->last_set_pages = 0;
>>         return 0;
>>   }
>> @@ -1383,7 +1374,6 @@ bool amdgpu_ttm_tt_affect_userptr(struct ttm_tt 
>> *ttm, unsigned long start,
>>                     unsigned long end)
>>   {
>>       struct amdgpu_ttm_tt *gtt = (void *)ttm;
>> -    struct amdgpu_ttm_gup_task_list *entry;
>>       unsigned long size;
>>         if (gtt == NULL || !gtt->userptr)
>> @@ -1396,48 +1386,20 @@ bool amdgpu_ttm_tt_affect_userptr(struct 
>> ttm_tt *ttm, unsigned long start,
>>       if (gtt->userptr > end || gtt->userptr + size <= start)
>>           return false;
>>   -    /* Search the lists of tasks that hold this mapping and see
>> -     * if current is one of them.  If it is return false.
>> -     */
>> -    spin_lock(&gtt->guptasklock);
>> -    list_for_each_entry(entry, &gtt->guptasks, list) {
>> -        if (entry->task == current) {
>> -            spin_unlock(&gtt->guptasklock);
>> -            return false;
>> -        }
>> -    }
>> -    spin_unlock(&gtt->guptasklock);
>> -
>> -    atomic_inc(&gtt->mmu_invalidations);
>> -
>>       return true;
>>   }
>>     /**
>> - * amdgpu_ttm_tt_userptr_invalidated - Has the ttm_tt object been 
>> invalidated?
>> + * amdgpu_ttm_tt_is_userptr - Have the pages backing by userptr?
>>    */
>> -bool amdgpu_ttm_tt_userptr_invalidated(struct ttm_tt *ttm,
>> -                       int *last_invalidated)
>> -{
>> -    struct amdgpu_ttm_tt *gtt = (void *)ttm;
>> -    int prev_invalidated = *last_invalidated;
>> -
>> -    *last_invalidated = atomic_read(&gtt->mmu_invalidations);
>> -    return prev_invalidated != *last_invalidated;
>> -}
>> -
>> -/**
>> - * amdgpu_ttm_tt_userptr_needs_pages - Have the pages backing this 
>> ttm_tt object
>> - * been invalidated since the last time they've been set?
>> - */
>> -bool amdgpu_ttm_tt_userptr_needs_pages(struct ttm_tt *ttm)
>> +bool amdgpu_ttm_tt_is_userptr(struct ttm_tt *ttm)
>>   {
>>       struct amdgpu_ttm_tt *gtt = (void *)ttm;
>>         if (gtt == NULL || !gtt->userptr)
>>           return false;
>>   -    return atomic_read(&gtt->mmu_invalidations) != 
>> gtt->last_set_pages;
>> +    return true;
>>   }
>>     /**
>> diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.h 
>> b/drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.h
>> index fe8f276..aeeea77 100644
>> --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.h
>> +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.h
>> @@ -104,6 +104,7 @@ int amdgpu_ttm_alloc_gart(struct 
>> ttm_buffer_object *bo);
>>   int amdgpu_ttm_recover_gart(struct ttm_buffer_object *tbo);
>>     int amdgpu_ttm_tt_get_user_pages(struct ttm_tt *ttm, struct page 
>> **pages);
>> +bool amdgpu_ttm_tt_get_user_pages_done(struct ttm_tt *ttm);
>>   void amdgpu_ttm_tt_set_user_pages(struct ttm_tt *ttm, struct page 
>> **pages);
>>   void amdgpu_ttm_tt_mark_user_pages(struct ttm_tt *ttm);
>>   int amdgpu_ttm_tt_set_userptr(struct ttm_tt *ttm, uint64_t addr,
>> @@ -114,7 +115,7 @@ bool amdgpu_ttm_tt_affect_userptr(struct ttm_tt 
>> *ttm, unsigned long start,
>>                     unsigned long end);
>>   bool amdgpu_ttm_tt_userptr_invalidated(struct ttm_tt *ttm,
>>                          int *last_invalidated);
>> -bool amdgpu_ttm_tt_userptr_needs_pages(struct ttm_tt *ttm);
>> +bool amdgpu_ttm_tt_is_userptr(struct ttm_tt *ttm);
>>   bool amdgpu_ttm_tt_is_readonly(struct ttm_tt *ttm);
>>   uint64_t amdgpu_ttm_tt_pde_flags(struct ttm_tt *ttm, struct 
>> ttm_mem_reg *mem);
>>   uint64_t amdgpu_ttm_tt_pte_flags(struct amdgpu_device *adev, struct 
>> ttm_tt *ttm,
>> diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_vm.c 
>> b/drivers/gpu/drm/amd/amdgpu/amdgpu_vm.c
>> index 6904d79..fa5bf45 100644
>> --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_vm.c
>> +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_vm.c
>> @@ -617,7 +617,6 @@ void amdgpu_vm_get_pd_bo(struct amdgpu_vm *vm,
>>       entry->priority = 0;
>>       entry->tv.bo = &vm->root.base.bo->tbo;
>>       entry->tv.shared = true;
>> -    entry->user_pages = NULL;
>>       list_add(&entry->tv.head, validated);
>>   }
>

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