[PATCH] drm/ttm: fix busy memory to fail other user
Christian König
ckoenig.leichtzumerken at gmail.com
Thu Apr 25 06:56:51 UTC 2019
Am 24.04.19 um 13:40 schrieb Chunming Zhou:
> basically pick up Christian idea:
>
> 1. Reserve the BO in DC using a ww_mutex ticket (trivial).
Please split that step into a separate patch.
> 2. If we then run into this EBUSY condition in TTM check if the BO we need memory for (or rather the ww_mutex of its reservation object) has a ticket assigned.
> 3. If we have a ticket we grab a reference to the first BO on the LRU, drop the LRU lock and try to grab the reservation lock with the ticket.
> 4. If getting the reservation lock with the ticket succeeded we check if the BO is still the first one on the LRU in question (the BO could have moved).
> 5. If the BO is still the first one on the LRU in question we try to evict it as we would evict any other BO.
> 6. If any of the "If's" above fail we just back off and return -EBUSY.
>
> Change-Id: I21423fb922f885465f13833c41df1e134364a8e7
> Signed-off-by: Chunming Zhou <david1.zhou at amd.com>
> ---
> drivers/gpu/drm/amd/amdgpu/amdgpu_object.c | 14 ++++-
> drivers/gpu/drm/amd/amdgpu/amdgpu_object.h | 3 +-
> drivers/gpu/drm/amd/amdgpu/amdgpu_ras.c | 2 +-
> drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c | 2 +-
> .../gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c | 22 +++++--
> drivers/gpu/drm/ttm/ttm_bo.c | 58 +++++++++++++++++--
> include/drm/ttm/ttm_bo_api.h | 1 +
> 7 files changed, 86 insertions(+), 16 deletions(-)
>
> diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_object.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_object.c
> index affde72b44db..e08ff2244070 100644
> --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_object.c
> +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_object.c
> @@ -791,6 +791,7 @@ void amdgpu_bo_unref(struct amdgpu_bo **bo)
> * @domain: domain to be pinned to
> * @min_offset: the start of requested address range
> * @max_offset: the end of requested address range
> + * @ticket: struct ww_acquire_ctx ticket, if the pin BO has a ticket assigned
> *
> * Pins the buffer object according to requested domain and address range. If
> * the memory is unbound gart memory, binds the pages into gart table. Adjusts
> @@ -808,10 +809,17 @@ void amdgpu_bo_unref(struct amdgpu_bo **bo)
> * 0 for success or a negative error code on failure.
> */
> int amdgpu_bo_pin_restricted(struct amdgpu_bo *bo, u32 domain,
> - u64 min_offset, u64 max_offset)
> + u64 min_offset, u64 max_offset,
> + struct ww_acquire_ctx *ticket)
> {
> struct amdgpu_device *adev = amdgpu_ttm_adev(bo->tbo.bdev);
> - struct ttm_operation_ctx ctx = { false, false };
> + struct ttm_operation_ctx ctx = {
> + .interruptible = false,
> + .no_wait_gpu = false,
> + .resv = bo->tbo.resv,
> + .ticket = ticket,
We can actually get the ticket from the BO using bo->resv->lock.ctx.
That should make the whole patch less work.
> + .flags = TTM_OPT_FLAG_ALLOW_RES_EVICT
> + };
> int r, i;
>
> if (amdgpu_ttm_tt_get_usermm(bo->tbo.ttm))
> @@ -907,7 +915,7 @@ int amdgpu_bo_pin_restricted(struct amdgpu_bo *bo, u32 domain,
> */
> int amdgpu_bo_pin(struct amdgpu_bo *bo, u32 domain)
> {
> - return amdgpu_bo_pin_restricted(bo, domain, 0, 0);
> + return amdgpu_bo_pin_restricted(bo, domain, 0, 0, NULL);
> }
>
> /**
> diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_object.h b/drivers/gpu/drm/amd/amdgpu/amdgpu_object.h
> index c430e8259038..41e7fff7f3f2 100644
> --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_object.h
> +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_object.h
> @@ -247,7 +247,8 @@ struct amdgpu_bo *amdgpu_bo_ref(struct amdgpu_bo *bo);
> void amdgpu_bo_unref(struct amdgpu_bo **bo);
> int amdgpu_bo_pin(struct amdgpu_bo *bo, u32 domain);
> int amdgpu_bo_pin_restricted(struct amdgpu_bo *bo, u32 domain,
> - u64 min_offset, u64 max_offset);
> + u64 min_offset, u64 max_offset,
> + struct ww_acquire_ctx *ticket);
> int amdgpu_bo_unpin(struct amdgpu_bo *bo);
> int amdgpu_bo_evict_vram(struct amdgpu_device *adev);
> int amdgpu_bo_init(struct amdgpu_device *adev);
> diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_ras.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_ras.c
> index 22bd21efe6b1..dd31ce1a09e3 100644
> --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_ras.c
> +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_ras.c
> @@ -1150,7 +1150,7 @@ static int amdgpu_ras_reserve_vram(struct amdgpu_device *adev,
> r = amdgpu_bo_pin_restricted(bo,
> AMDGPU_GEM_DOMAIN_VRAM,
> offset,
> - offset + size);
> + offset + size, NULL);
> if (r)
> goto error_pin;
>
> diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c
> index afccca5b1f5f..e63af0debc7a 100644
> --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c
> +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c
> @@ -1661,7 +1661,7 @@ static int amdgpu_ttm_fw_reserve_vram_init(struct amdgpu_device *adev)
> AMDGPU_GEM_DOMAIN_VRAM,
> adev->fw_vram_usage.start_offset,
> (adev->fw_vram_usage.start_offset +
> - adev->fw_vram_usage.size));
> + adev->fw_vram_usage.size), NULL);
> if (r)
> goto error_pin;
> r = amdgpu_bo_kmap(adev->fw_vram_usage.reserved_bo,
> diff --git a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c
> index a5cacf846e1b..bdbbc3891585 100644
> --- a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c
> +++ b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c
> @@ -4101,6 +4101,9 @@ static int dm_plane_helper_prepare_fb(struct drm_plane *plane,
> struct amdgpu_device *adev;
> struct amdgpu_bo *rbo;
> struct dm_plane_state *dm_plane_state_new, *dm_plane_state_old;
> + struct list_head list, duplicates;
> + struct ttm_validate_buffer tv;
> + struct ww_acquire_ctx ticket;
> uint64_t tiling_flags;
> uint32_t domain;
> int r;
> @@ -4119,32 +4122,43 @@ static int dm_plane_helper_prepare_fb(struct drm_plane *plane,
> adev = amdgpu_ttm_adev(rbo->tbo.bdev);
> r = amdgpu_bo_reserve(rbo, false);
> if (unlikely(r != 0))
> + INIT_LIST_HEAD(&list);
> + INIT_LIST_HEAD(&duplicates);
> +
> + tv.bo = &rbo->tbo;
> + tv.num_shared = 1;
> + list_add(&tv.head, &list);
> +
> + r = ttm_eu_reserve_buffers(&ticket, &list, false, &duplicates);
> + if (r) {
> + dev_err(adev->dev, "fail to reserve bo (%d)\n", r);
> return r;
> + }
>
> if (plane->type != DRM_PLANE_TYPE_CURSOR)
> domain = amdgpu_display_supported_domains(adev);
> else
> domain = AMDGPU_GEM_DOMAIN_VRAM;
>
> - r = amdgpu_bo_pin(rbo, domain);
> + r = amdgpu_bo_pin_restricted(rbo, domain, 0, 0, &ticket);
> if (unlikely(r != 0)) {
> if (r != -ERESTARTSYS)
> DRM_ERROR("Failed to pin framebuffer with error %d\n", r);
> - amdgpu_bo_unreserve(rbo);
> + ttm_eu_backoff_reservation(&ticket, &list);
> return r;
> }
>
> r = amdgpu_ttm_alloc_gart(&rbo->tbo);
> if (unlikely(r != 0)) {
> amdgpu_bo_unpin(rbo);
> - amdgpu_bo_unreserve(rbo);
> + ttm_eu_backoff_reservation(&ticket, &list);
> DRM_ERROR("%p bind failed\n", rbo);
> return r;
> }
>
> amdgpu_bo_get_tiling_flags(rbo, &tiling_flags);
>
> - amdgpu_bo_unreserve(rbo);
> + ttm_eu_backoff_reservation(&ticket, &list);
>
> afb->address = amdgpu_bo_gpu_offset(rbo);
>
> diff --git a/drivers/gpu/drm/ttm/ttm_bo.c b/drivers/gpu/drm/ttm/ttm_bo.c
> index 8502b3ed2d88..112fea8f21f9 100644
> --- a/drivers/gpu/drm/ttm/ttm_bo.c
> +++ b/drivers/gpu/drm/ttm/ttm_bo.c
> @@ -766,11 +766,12 @@ EXPORT_SYMBOL(ttm_bo_eviction_valuable);
> * b. Otherwise, trylock it.
> */
> static bool ttm_bo_evict_swapout_allowable(struct ttm_buffer_object *bo,
> - struct ttm_operation_ctx *ctx, bool *locked)
> + struct ttm_operation_ctx *ctx, bool *locked, bool *busy)
> {
> bool ret = false;
>
> *locked = false;
> + *busy = false;
> if (bo->resv == ctx->resv) {
> reservation_object_assert_held(bo->resv);
> if (ctx->flags & TTM_OPT_FLAG_ALLOW_RES_EVICT
> @@ -779,6 +780,8 @@ static bool ttm_bo_evict_swapout_allowable(struct ttm_buffer_object *bo,
> } else {
> *locked = reservation_object_trylock(bo->resv);
> ret = *locked;
> + if (ret)
> + *busy = true;
> }
>
> return ret;
> @@ -791,16 +794,20 @@ static int ttm_mem_evict_first(struct ttm_bo_device *bdev,
> {
> struct ttm_bo_global *glob = bdev->glob;
> struct ttm_mem_type_manager *man = &bdev->man[mem_type];
> - struct ttm_buffer_object *bo = NULL;
> - bool locked = false;
> + struct ttm_buffer_object *bo = NULL, *first_bo = NULL;
> + bool locked = false, list_busy = false;
> unsigned i;
> int ret;
>
> spin_lock(&glob->lru_lock);
> for (i = 0; i < TTM_MAX_BO_PRIORITY; ++i) {
> list_for_each_entry(bo, &man->lru[i], lru) {
> - if (!ttm_bo_evict_swapout_allowable(bo, ctx, &locked))
> + bool busy = false;
> + if (!ttm_bo_evict_swapout_allowable(bo, ctx, &locked,
> + &busy)) {
> + list_busy |= busy;
> continue;
> + }
>
> if (place && !bdev->driver->eviction_valuable(bo,
> place)) {
> @@ -819,8 +826,44 @@ static int ttm_mem_evict_first(struct ttm_bo_device *bdev,
> }
>
> if (!bo) {
> + for (i = 0; i < TTM_MAX_BO_PRIORITY; ++i) {
> + if (list_empty(&man->lru[i]))
> + continue;
> + bo = list_first_entry(&man->lru[i],
> + struct ttm_buffer_object,
> + lru);
> +
> + break;
> + }
Maybe keep the first busy BO from the list walk above instead of the
list_busy flag.
> spin_unlock(&glob->lru_lock);
> - return -EBUSY;
> + if (!list_busy || !ctx->ticket)
> + return -EBUSY;
> + if (ctx->interruptible) {
> + ret = ww_mutex_lock_slow_interruptible(&bo->resv->lock,
> + ctx->ticket);
> + } else {
> + ww_mutex_lock_slow(&bo->resv->lock, ctx->ticket);
You MUST use the ww_mutex_lock and ww_mutex_lock_interruptible funtions
here and NOT the slow path versions.
AND then check the return code for a deadlock.
Christian.
> + ret = 0;
> + }
> + if (ret)
> + return ret;
> + spin_lock(&glob->lru_lock);
> + for (i = 0; i < TTM_MAX_BO_PRIORITY; ++i) {
> + if (list_empty(&man->lru[i]))
> + continue;
> + first_bo = list_first_entry(&man->lru[i],
> + struct ttm_buffer_object,
> + lru);
> +
> + break;
> + }
> + spin_unlock(&glob->lru_lock);
> + /* verify if BO have been moved */
> + if (first_bo != bo) {
> + ww_mutex_unlock(&bo->resv->lock);
> + return -EBUSY;
> + }
> + /* ok, pick up first busy BO to wait to evict */
> }
>
> kref_get(&bo->list_kref);
> @@ -1784,7 +1827,10 @@ int ttm_bo_swapout(struct ttm_bo_global *glob, struct ttm_operation_ctx *ctx)
> spin_lock(&glob->lru_lock);
> for (i = 0; i < TTM_MAX_BO_PRIORITY; ++i) {
> list_for_each_entry(bo, &glob->swap_lru[i], swap) {
> - if (ttm_bo_evict_swapout_allowable(bo, ctx, &locked)) {
> + bool busy = false;
> +
> + if (ttm_bo_evict_swapout_allowable(bo, ctx, &locked,
> + &busy)) {
> ret = 0;
> break;
> }
> diff --git a/include/drm/ttm/ttm_bo_api.h b/include/drm/ttm/ttm_bo_api.h
> index 49d9cdfc58f2..5bb879f117e3 100644
> --- a/include/drm/ttm/ttm_bo_api.h
> +++ b/include/drm/ttm/ttm_bo_api.h
> @@ -276,6 +276,7 @@ struct ttm_operation_ctx {
> bool interruptible;
> bool no_wait_gpu;
> struct reservation_object *resv;
> + struct ww_acquire_ctx *ticket;
> uint64_t bytes_moved;
> uint32_t flags;
> };
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