[PATCH 3/3] drm/amdgpu: replace get_user_pages with HMM address mirror helpers v7

Yang, Philip Philip.Yang at amd.com
Wed Feb 6 15:53:14 UTC 2019


 >> +    /* 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;
 >> -        }
 >> +        r |= !amdgpu_ttm_tt_get_user_pages_done(bo->tbo.ttm);
 >
 > Just abort when you see the first one with a problem here.
 >
 > There is no value in checking all of them.
 >
No, amdgpu_ttm_tt_get_user_pages_done calls hmm_vma_range_done to stop 
HMM track and free range structure memory, this needs go through all 
userptr BOs.

 >> +
 >> +    if (r == -EAGAIN) {
 >> +        if (!--tries) {
 >> +            DRM_ERROR("Possible deadlock? Retry too many times\n");
 >> +            return -EDEADLK;
 >> +        }
 >> +        goto restart;
 >> +    }
 >> +
 >
 > I would still say to better just return to userspace here.
 >
 > Because of the way HMM works 10 retries might not be sufficient any more.
 >
Yes, it looks better to handle retry from user space. The extra sys call 
overhead can be ignored because this does not happen all the time. I 
will submit new patch for review.

Thanks,
Philip

On 2019-02-06 4:20 a.m., Christian König wrote:
> Am 05.02.19 um 23:00 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.
>>
>> HMM simplify the CPU page table concurrent update check, so remove
>> guptasklock, mmu_invalidations, last_set_pages fields from
>> amdgpu_ttm_tt struct.
>>
>> HMM does not pin the page (increase page ref count), so remove related
>> operations like release_pages(), put_page(), mark_page_dirty().
>>
>> Change-Id: I2e8c0c6f0d8c21e5596a32d7fc91762778bc9e67
>> Signed-off-by: Philip Yang <Philip.Yang at amd.com>
>> ---
>>   drivers/gpu/drm/amd/amdgpu/amdgpu_amdkfd.h    |   1 -
>>   .../gpu/drm/amd/amdgpu/amdgpu_amdkfd_gpuvm.c  |  95 +++-------
>>   drivers/gpu/drm/amd/amdgpu/amdgpu_bo_list.h   |   2 +-
>>   drivers/gpu/drm/amd/amdgpu/amdgpu_cs.c        | 158 +++++++---------
>>   drivers/gpu/drm/amd/amdgpu/amdgpu_gem.c       |  14 +-
>>   drivers/gpu/drm/amd/amdgpu/amdgpu_mn.c        |  25 ++-
>>   drivers/gpu/drm/amd/amdgpu/amdgpu_mn.h        |   4 +-
>>   drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c       | 178 +++++++-----------
>>   drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.h       |   3 +-
>>   9 files changed, 198 insertions(+), 282 deletions(-)
>>
>> diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_amdkfd.h 
>> b/drivers/gpu/drm/amd/amdgpu/amdgpu_amdkfd.h
>> index 0b31a1859023..0e1711a75b68 100644
>> --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_amdkfd.h
>> +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_amdkfd.h
>> @@ -61,7 +61,6 @@ struct kgd_mem {
>>       atomic_t invalid;
>>       struct amdkfd_process_info *process_info;
>> -    struct page **user_pages;
>>       struct amdgpu_sync sync;
>> diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_amdkfd_gpuvm.c 
>> b/drivers/gpu/drm/amd/amdgpu/amdgpu_amdkfd_gpuvm.c
>> index d7b10d79f1de..ae2d838d31ea 100644
>> --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_amdkfd_gpuvm.c
>> +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_amdkfd_gpuvm.c
>> @@ -582,28 +582,12 @@ static int init_user_pages(struct kgd_mem *mem, 
>> struct mm_struct *mm,
>>           goto out;
>>       }
>> -    /* If no restore worker is running concurrently, user_pages
>> -     * should not be allocated
>> -     */
>> -    WARN(mem->user_pages, "Leaking user_pages array");
>> -
>> -    mem->user_pages = kvmalloc_array(bo->tbo.ttm->num_pages,
>> -                       sizeof(struct page *),
>> -                       GFP_KERNEL | __GFP_ZERO);
>> -    if (!mem->user_pages) {
>> -        pr_err("%s: Failed to allocate pages array\n", __func__);
>> -        ret = -ENOMEM;
>> -        goto unregister_out;
>> -    }
>> -
>> -    ret = amdgpu_ttm_tt_get_user_pages(bo->tbo.ttm, mem->user_pages);
>> +    ret = amdgpu_ttm_tt_get_user_pages(bo->tbo.ttm, bo->tbo.ttm->pages);
>>       if (ret) {
>>           pr_err("%s: Failed to get user pages: %d\n", __func__, ret);
>> -        goto free_out;
>> +        goto unregister_out;
>>       }
>> -    amdgpu_ttm_tt_set_user_pages(bo->tbo.ttm, mem->user_pages);
>> -
>>       ret = amdgpu_bo_reserve(bo, true);
>>       if (ret) {
>>           pr_err("%s: Failed to reserve BO\n", __func__);
>> @@ -616,11 +600,7 @@ 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);
>> -free_out:
>> -    kvfree(mem->user_pages);
>> -    mem->user_pages = NULL;
>> +    amdgpu_ttm_tt_get_user_pages_done(bo->tbo.ttm);
>>   unregister_out:
>>       if (ret)
>>           amdgpu_mn_unregister(bo);
>> @@ -679,7 +659,6 @@ 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.num_shared = 1;
>> -    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]);
>> @@ -743,7 +722,6 @@ 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.num_shared = 1;
>> -    ctx->kfd_bo.user_pages = NULL;
>>       list_add(&ctx->kfd_bo.tv.head, &ctx->list);
>>       i = 0;
>> @@ -1371,15 +1349,6 @@ int amdgpu_amdkfd_gpuvm_free_memory_of_gpu(
>>       list_del(&bo_list_entry->head);
>>       mutex_unlock(&process_info->lock);
>> -    /* 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);
>> -    }
>> -
>>       ret = reserve_bo_and_cond_vms(mem, NULL, BO_VM_ALL, &ctx);
>>       if (unlikely(ret))
>>           return ret;
>> @@ -1855,25 +1824,11 @@ static int update_invalid_user_pages(struct 
>> amdkfd_process_info *process_info,
>>           bo = mem->bo;
>> -        if (!mem->user_pages) {
>> -            mem->user_pages =
>> -                kvmalloc_array(bo->tbo.ttm->num_pages,
>> -                         sizeof(struct page *),
>> -                         GFP_KERNEL | __GFP_ZERO);
>> -            if (!mem->user_pages) {
>> -                pr_err("%s: Failed to allocate pages array\n",
>> -                       __func__);
>> -                return -ENOMEM;
>> -            }
>> -        } else if (mem->user_pages[0]) {
>> -            release_pages(mem->user_pages, bo->tbo.ttm->num_pages);
>> -        }
>> -
>>           /* Get updated user pages */
>>           ret = amdgpu_ttm_tt_get_user_pages(bo->tbo.ttm,
>> -                           mem->user_pages);
>> +                           bo->tbo.ttm->pages);
>>           if (ret) {
>> -            mem->user_pages[0] = NULL;
>> +            bo->tbo.ttm->pages[0] = NULL;
>>               pr_info("%s: Failed to get user pages: %d\n",
>>                   __func__, ret);
>>               /* Pretend it succeeded. It will fail later
>> @@ -1882,12 +1837,6 @@ 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;
>> @@ -1917,7 +1866,8 @@ static int validate_invalid_user_pages(struct 
>> amdkfd_process_info *process_info)
>>                        GFP_KERNEL);
>>       if (!pd_bo_list_entries) {
>>           pr_err("%s: Failed to allocate PD BO list entries\n", 
>> __func__);
>> -        return -ENOMEM;
>> +        ret = -ENOMEM;
>> +        goto out_no_mem;
>>       }
>>       INIT_LIST_HEAD(&resv_list);
>> @@ -1941,7 +1891,7 @@ static int validate_invalid_user_pages(struct 
>> amdkfd_process_info *process_info)
>>       ret = ttm_eu_reserve_buffers(&ticket, &resv_list, false, 
>> &duplicates);
>>       WARN(!list_empty(&duplicates), "Duplicates should be empty");
>>       if (ret)
>> -        goto out;
>> +        goto out_free;
>>       amdgpu_sync_create(&sync);
>> @@ -1967,10 +1917,8 @@ static int validate_invalid_user_pages(struct 
>> amdkfd_process_info *process_info)
>>           bo = mem->bo;
>> -        /* Copy pages array and validate the BO if we got user pages */
>> -        if (mem->user_pages[0]) {
>> -            amdgpu_ttm_tt_set_user_pages(bo->tbo.ttm,
>> -                             mem->user_pages);
>> +        /* Validate the BO if we got user pages */
>> +        if (bo->tbo.ttm->pages[0]) {
>>               amdgpu_bo_placement_from_domain(bo, mem->domain);
>>               ret = ttm_bo_validate(&bo->tbo, &bo->placement, &ctx);
>>               if (ret) {
>> @@ -1979,16 +1927,16 @@ 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.
>> -         */
>> -        kvfree(mem->user_pages);
>> -        mem->user_pages = NULL;
>>           list_move_tail(&mem->validate_list.head,
>>                      &process_info->userptr_valid_list);
>> +        /* Stop HMM track the userptr update. We dont check the return
>> +         * value for concurrent CPU page table update because we will
>> +         * reschedule the restore worker if process_info->evicted_bos
>> +         * is updated.
>> +         */
>> +        amdgpu_ttm_tt_get_user_pages_done(bo->tbo.ttm);
>> +
>>           /* 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
>> @@ -2022,8 +1970,15 @@ static int validate_invalid_user_pages(struct 
>> amdkfd_process_info *process_info)
>>       ttm_eu_backoff_reservation(&ticket, &resv_list);
>>       amdgpu_sync_wait(&sync, false);
>>       amdgpu_sync_free(&sync);
>> -out:
>> +out_free:
>>       kfree(pd_bo_list_entries);
>> +out_no_mem:
>> +    list_for_each_entry_safe(mem, tmp_mem,
>> +                 &process_info->userptr_inval_list,
>> +                 validate_list.head) {
>> +        bo = mem->bo;
>> +        amdgpu_ttm_tt_get_user_pages_done(bo->tbo.ttm);
>> +    }
>>       return ret;
>>   }
>> diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_bo_list.h 
>> b/drivers/gpu/drm/amd/amdgpu/amdgpu_bo_list.h
>> index 7c5f5d1601e6..a130e766cbdb 100644
>> --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_bo_list.h
>> +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_bo_list.h
>> @@ -36,7 +36,7 @@ struct amdgpu_bo_list_entry {
>>       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 52a5e4fdc95b..70bdf9ff0bab 100644
>> --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_cs.c
>> +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_cs.c
>> @@ -52,7 +52,6 @@ static int amdgpu_cs_user_fence_chunk(struct 
>> amdgpu_cs_parser *p,
>>       p->uf_entry.tv.bo = &bo->tbo;
>>       /* One for TTM and one for the CS job */
>>       p->uf_entry.tv.num_shared = 2;
>> -    p->uf_entry.user_pages = NULL;
>>       drm_gem_object_put_unlocked(gobj);
>> @@ -540,14 +539,14 @@ static int amdgpu_cs_list_validate(struct 
>> amdgpu_cs_parser *p,
>>           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 && lobj->user_pages) {
>>               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;
>> @@ -578,7 +577,6 @@ 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);
>> @@ -614,79 +612,45 @@ 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;
>> -            }
>> -
>> -            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);
>> -
>> -                amdgpu_bo_unreserve(bo);
>> -            }
>> +    /* 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);
>> +        bool userpage_invalidated = false;
>> +        int i;
>> +
>> +        e->user_pages = kvmalloc_array(bo->tbo.ttm->num_pages,
>> +                    sizeof(struct page *),
>> +                    GFP_KERNEL | __GFP_ZERO);
>> +        if (!e->user_pages) {
>> +            DRM_ERROR("calloc failure\n");
>> +            return -ENOMEM;
>>           }
>> -        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;
>> +        r = amdgpu_ttm_tt_get_user_pages(bo->tbo.ttm, e->user_pages);
>> +        if (r) {
>> +            kvfree(e->user_pages);
>> +            e->user_pages = NULL;
>> +            return r;
>>           }
>> -        /* 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;
>> +        for (i = 0; i < bo->tbo.ttm->num_pages; i++) {
>> +            if (bo->tbo.ttm->pages[i] != e->user_pages[i]) {
>> +                userpage_invalidated = true;
>> +                break;
>>               }
>>           }
>> +        e->user_invalidated = userpage_invalidated;
>> +    }
>> -        /* 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,
>> @@ -755,17 +719,7 @@ 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:
>>       return r;
>>   }
>> @@ -1224,8 +1178,7 @@ 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;
>> @@ -1234,15 +1187,21 @@ 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 */
>> +    /* 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);
>> +
>> +    /* 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;
>> -        }
>> +        r |= !amdgpu_ttm_tt_get_user_pages_done(bo->tbo.ttm);
> 
> Just abort when you see the first one with a problem here.
> 
> There is no value in checking all of them.
> 
>> +    }
>> +    if (r) {
>> +        r = -EAGAIN;
>> +        goto error_abort;
>>       }
>>       job->owner = p->filp;
>> @@ -1289,14 +1248,20 @@ 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;
>> @@ -1338,6 +1303,15 @@ 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 == -EAGAIN) {
>> +        if (!--tries) {
>> +            DRM_ERROR("Possible deadlock? Retry too many times\n");
>> +            return -EDEADLK;
>> +        }
>> +        goto restart;
>> +    }
>> +
> 
> I would still say to better just return to userspace here.
> 
> Because of the way HMM works 10 retries might not be sufficient any more.
> 
> Christian.
> 
>>       return r;
>>   }
>> diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_gem.c 
>> b/drivers/gpu/drm/amd/amdgpu/amdgpu_gem.c
>> index d21dd2f369da..555285e329ed 100644
>> --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_gem.c
>> +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_gem.c
>> @@ -329,26 +329,24 @@ 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 e356867d2308..fa2516016c43 100644
>> --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_mn.c
>> +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_mn.c
>> @@ -222,8 +222,6 @@ 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);
>>       }
>>   }
>> @@ -504,3 +502,26 @@ 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 0a51fd00021c..4803e216e174 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,
>> @@ -41,6 +42,7 @@ struct amdgpu_mn *amdgpu_mn_get(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 73e71e61dc99..1e675048f790 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"
>> @@ -705,98 +706,102 @@ 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;
>>       uint64_t        userptr;
>>       struct task_struct    *usertask;
>>       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 = 0, 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_in_vma(range->vma, gtt->userptr, end))
>> +        r = -EFAULT;
>> +    else if ((gtt->userflags & AMDGPU_GEM_USERPTR_ANONONLY) &&
>> +        range->vma->vm_file)
>> +        r = -EPERM;
>> +    if (r)
>> +        goto out;
>> -        vma = find_vma(mm, gtt->userptr);
>> -        if (!vma || vma->vm_file || vma->vm_end < end) {
>> -            up_read(&mm->mmap_sem);
>> -            return -EPERM;
>> -        }
>> +    range->pfns = kvmalloc_array(ttm->num_pages, sizeof(uint64_t),
>> +                     GFP_KERNEL);
>> +    if (range->pfns == NULL) {
>> +        r = -ENOMEM;
>> +        goto out;
>>       }
>> +    range->start = gtt->userptr;
>> +    range->end = end;
>> -    /* 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;
>> +    range->pfns[0] = range->flags[HMM_PFN_VALID];
>> +    range->pfns[0] |= amdgpu_ttm_tt_is_readonly(ttm) ?
>> +                0 : range->flags[HMM_PFN_WRITE];
>> +    for (i = 1; i < ttm->num_pages; i++)
>> +        range->pfns[i] = range->pfns[0];
>> -        guptask.task = current;
>> -        spin_lock(&gtt->guptasklock);
>> -        list_add(&guptask.list, &gtt->guptasks);
>> -        spin_unlock(&gtt->guptasklock);
>> +    /* This may trigger page table update */
>> +    r = hmm_vma_fault(range, true);
>> +    if (r)
>> +        goto out_free_pfns;
>> -        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);
>> -        spin_lock(&gtt->guptasklock);
>> -        list_del(&guptask.list);
>> -        spin_unlock(&gtt->guptasklock);
>> +    for (i = 0; i < ttm->num_pages; i++)
>> +        pages[i] = hmm_pfn_to_page(range, range->pfns[i]);
>> -        if (r < 0)
>> -            goto release_pages;
>> +    return 0;
>> -        pinned += r;
>> +out_free_pfns:
>> +    kvfree(range->pfns);
>> +    range->pfns = NULL;
>> +out:
>> +    up_read(&mm->mmap_sem);
>> +    return r;
>> +}
>> -    } while (pinned < ttm->num_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 still valid
>> + */
>> +bool amdgpu_ttm_tt_get_user_pages_done(struct ttm_tt *ttm)
>> +{
>> +    struct amdgpu_ttm_tt *gtt = (void *)ttm;
>> +    bool r = false;
>> -    up_read(&mm->mmap_sem);
>> -    return 0;
>> +    if (!gtt || !gtt->userptr)
>> +        return false;
>> +
>> +    WARN_ONCE(!gtt->range.pfns, "No user pages to check\n");
>> +    if (gtt->range.pfns) {
>> +        r = hmm_vma_range_done(&gtt->range);
>> +        kvfree(gtt->range.pfns);
>> +        gtt->range.pfns = NULL;
>> +    }
>> -release_pages:
>> -    release_pages(pages, pinned);
>> -    up_read(&mm->mmap_sem);
>>       return r;
>>   }
>> @@ -809,16 +814,10 @@ 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;
>> -    }
>>   }
>>   /**
>> @@ -903,10 +902,11 @@ 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);
>> +
>> +    if (gtt->range.pfns &&
>> +        ttm->pages[0] == hmm_pfn_to_page(&gtt->range, 
>> gtt->range.pfns[0]))
>> +        WARN_ONCE(1, "Missing get_user_page_done\n");
>>   }
>>   int amdgpu_ttm_gart_bind(struct amdgpu_device *adev,
>> @@ -1256,11 +1256,6 @@ int amdgpu_ttm_tt_set_userptr(struct ttm_tt 
>> *ttm, uint64_t addr,
>>       gtt->usertask = current->group_leader;
>>       get_task_struct(gtt->usertask);
>> -    spin_lock_init(&gtt->guptasklock);
>> -    INIT_LIST_HEAD(&gtt->guptasks);
>> -    atomic_set(&gtt->mmu_invalidations, 0);
>> -    gtt->last_set_pages = 0;
>> -
>>       return 0;
>>   }
>> @@ -1289,7 +1284,6 @@ 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)
>> @@ -1302,48 +1296,20 @@ 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 b5b2d101f7db..8988c87fff9d 100644
>> --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.h
>> +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.h
>> @@ -102,6 +102,7 @@ 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,
>> @@ -112,7 +113,7 @@ 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,
> 


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