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.
v2: fix some minor check
v3: address Christian v2 comments.
Change-Id: I21423fb922f885465f13833c41df1e134364a8e7
Signed-off-by: Chunming Zhou <david1.zhou@xxxxxxx>
---
drivers/gpu/drm/amd/amdgpu/amdgpu_object.c | 7 ++-
.../gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c | 21 ++++++--
drivers/gpu/drm/ttm/ttm_bo.c | 48 +++++++++++++++++--
3 files changed, 67 insertions(+), 9 deletions(-)
diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_object.c
b/drivers/gpu/drm/amd/amdgpu/amdgpu_object.c
index affde72b44db..015bf62277d0 100644
--- a/drivers/gpu/drm/amd/amdgpu/amdgpu_object.c
+++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_object.c
@@ -811,7 +811,12 @@ int amdgpu_bo_pin_restricted(struct amdgpu_bo
*bo, u32 domain,
u64 min_offset, u64 max_offset)
{
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,
+ .flags = TTM_OPT_FLAG_ALLOW_RES_EVICT
+ };
Please completely drop this chunk.
If we allow evicting BOs from the same process during pinning it could
lead to some unforeseen side effects.
int r, i;
if (amdgpu_ttm_tt_get_usermm(bo->tbo.ttm))
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..2957ac38dcb0 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;
@@ -4120,6 +4123,18 @@ static int dm_plane_helper_prepare_fb(struct
drm_plane *plane,
r = amdgpu_bo_reserve(rbo, false);
if (unlikely(r != 0))
return r;
+ 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);
@@ -4130,21 +4145,21 @@ static int dm_plane_helper_prepare_fb(struct
drm_plane *plane,
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);
This part looks good to me, but as noted above should probably be in a
separate patch.
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..dbcf958d1b43 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;
@@ -791,7 +794,7 @@ 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;
+ struct ttm_buffer_object *bo = NULL, *first_bo = NULL;
bool locked = false;
unsigned i;
int ret;
@@ -799,8 +802,13 @@ static int ttm_mem_evict_first(struct
ttm_bo_device *bdev,
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)) {
+ if (!first_bo && busy)
+ first_bo = bo;
continue;
+ }
if (place && !bdev->driver->eviction_valuable(bo,
place)) {
@@ -808,6 +816,7 @@ static int ttm_mem_evict_first(struct
ttm_bo_device *bdev,
reservation_object_unlock(bo->resv);
continue;
}
+
break;
}
@@ -820,7 +829,33 @@ static int ttm_mem_evict_first(struct
ttm_bo_device *bdev,
if (!bo) {
spin_unlock(&glob->lru_lock);
- return -EBUSY;
+ if (!first_bo || !ctx || !ctx->resv || !ctx->resv->lock.ctx)
Ah, now I see why you need the reservation object here.
+ return -EBUSY;
+ if (ctx->interruptible)
+ ret = ww_mutex_lock_interruptible(&bo->resv->lock,
+ ctx->resv->lock.ctx);
+ else
+ ret = ww_mutex_lock(&bo->resv->lock, ctx->resv->lock.ctx);
+ 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;
+ bo = list_first_entry(&man->lru[i],
+ struct ttm_buffer_object,
+ lru);
You now need to check all BOs on the LRU, cause the first one where a
trylock failed is not necessarily the first one on the list.
+
+ break;
+ }
+ /* verify if BO have been moved */
+ if (first_bo != bo) {
+ spin_unlock(&glob->lru_lock);
+ ww_mutex_unlock(&bo->resv->lock);
+ return -EBUSY;
+ }
+ spin_unlock(&glob->lru_lock);
+ /* ok, pick up first busy BO to wait to evict */
}
kref_get(&bo->list_kref);
@@ -1784,7 +1819,10 @@ 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;
Better make the parameter optional.
