[PATCH 02/11] drm/ttm: fix busy memory to fail other user v8

["Christian König" <ckoenig.leichtzumerken@gmail.com>]

From: Chunming Zhou <david1.zhou@amd.com>

heavy gpu job could occupy memory long time, which lead other user fail to get memory.

basically pick up Christian idea:

1. Reserve the BO in DC using a ww_mutex ticket (trivial).
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.
v4: fix some missing
v5: handle first_bo unlock and bo_get/put
v6: abstract unified iterate function, and handle all possible usecase not only pinned bo.
v7: pass request bo->resv to ttm_bo_evict_first
v8 (chk): minimal coding style fix

Change-Id: I21423fb922f885465f13833c41df1e134364a8e7
Signed-off-by: Chunming Zhou <david1.zhou@amd.com>
Reviewed-by: Christian König <christian.koenig@amd.com>
---
 drivers/gpu/drm/ttm/ttm_bo.c | 113 +++++++++++++++++++++++++++++------
 1 file changed, 96 insertions(+), 17 deletions(-)

diff --git a/drivers/gpu/drm/ttm/ttm_bo.c b/drivers/gpu/drm/ttm/ttm_bo.c
index 2845fceb2fbd..e634d3a36923 100644
--- a/drivers/gpu/drm/ttm/ttm_bo.c
+++ b/drivers/gpu/drm/ttm/ttm_bo.c
@@ -766,11 +766,13 @@ 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;
+	if (busy)
+		*busy = false;
 	if (bo->resv == ctx->resv) {
 		reservation_object_assert_held(bo->resv);
 		if (ctx->flags & TTM_OPT_FLAG_ALLOW_RES_EVICT
@@ -779,35 +781,46 @@ static bool ttm_bo_evict_swapout_allowable(struct ttm_buffer_object *bo,
 	} else {
 		*locked = reservation_object_trylock(bo->resv);
 		ret = *locked;
+		if (!ret && busy)
+			*busy = true;
 	}
 
 	return ret;
 }
 
-static int ttm_mem_evict_first(struct ttm_bo_device *bdev,
-			       uint32_t mem_type,
-			       const struct ttm_place *place,
-			       struct ttm_operation_ctx *ctx)
+static struct ttm_buffer_object*
+ttm_mem_find_evitable_bo(struct ttm_bo_device *bdev,
+			 struct ttm_mem_type_manager *man,
+			 const struct ttm_place *place,
+			 struct ttm_operation_ctx *ctx,
+			 struct ttm_buffer_object **first_bo,
+			 bool *locked)
 {
-	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;
-	unsigned i;
-	int ret;
+	int i;
 
-	spin_lock(&glob->lru_lock);
+	if (first_bo)
+		*first_bo = NULL;
 	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 && !(*first_bo) && busy) {
+					ttm_bo_get(bo);
+					*first_bo = bo;
+				}
 				continue;
+			}
 
 			if (place && !bdev->driver->eviction_valuable(bo,
 								      place)) {
-				if (locked)
+				if (*locked)
 					reservation_object_unlock(bo->resv);
 				continue;
 			}
+
 			break;
 		}
 
@@ -818,9 +831,69 @@ static int ttm_mem_evict_first(struct ttm_bo_device *bdev,
 		bo = NULL;
 	}
 
+	return bo;
+}
+
+static int ttm_mem_evict_first(struct ttm_bo_device *bdev,
+			       uint32_t mem_type,
+			       const struct ttm_place *place,
+			       struct ttm_operation_ctx *ctx,
+			       struct reservation_object *request_resv)
+{
+	struct ttm_bo_global *glob = bdev->glob;
+	struct ttm_mem_type_manager *man = &bdev->man[mem_type];
+	struct ttm_buffer_object *bo = NULL, *first_bo = NULL;
+	bool locked = false;
+	int ret;
+
+	spin_lock(&glob->lru_lock);
+	bo = ttm_mem_find_evitable_bo(bdev, man, place, ctx, &first_bo,
+				      &locked);
 	if (!bo) {
+		struct ww_acquire_ctx *acquire_ctx = request_resv->lock.ctx;
+		struct ttm_operation_ctx busy_ctx;
+
 		spin_unlock(&glob->lru_lock);
-		return -EBUSY;
+		/* check if other user occupy memory too long time */
+		if (!first_bo || !request_resv || !request_resv->lock.ctx) {
+			if (first_bo)
+				ttm_bo_put(first_bo);
+			return -EBUSY;
+		}
+		if (first_bo->resv == request_resv) {
+			ttm_bo_put(first_bo);
+			return -EBUSY;
+		}
+		if (ctx->interruptible)
+			ret = ww_mutex_lock_interruptible(&first_bo->resv->lock,
+							  acquire_ctx);
+		else
+			ret = ww_mutex_lock(&first_bo->resv->lock,
+					    acquire_ctx);
+		if (ret) {
+			ttm_bo_put(first_bo);
+			return ret;
+		}
+		spin_lock(&glob->lru_lock);
+		/* previous busy resv lock is held by above, idle now,
+		 * so let them evictable.
+		 */
+		busy_ctx.interruptible = ctx->interruptible;
+		busy_ctx.no_wait_gpu   = ctx->no_wait_gpu;
+		busy_ctx.resv	       = first_bo->resv;
+		busy_ctx.flags	       = TTM_OPT_FLAG_ALLOW_RES_EVICT;
+
+		bo = ttm_mem_find_evitable_bo(bdev, man, place, &busy_ctx, NULL,
+					      &locked);
+		if (bo && (bo->resv == first_bo->resv))
+			locked = true;
+		else if (bo)
+			ww_mutex_unlock(&first_bo->resv->lock);
+		if (!bo) {
+			spin_unlock(&glob->lru_lock);
+			ttm_bo_put(first_bo);
+			return -EBUSY;
+		}
 	}
 
 	kref_get(&bo->list_kref);
@@ -829,11 +902,15 @@ static int ttm_mem_evict_first(struct ttm_bo_device *bdev,
 		ret = ttm_bo_cleanup_refs(bo, ctx->interruptible,
 					  ctx->no_wait_gpu, locked);
 		kref_put(&bo->list_kref, ttm_bo_release_list);
+		if (first_bo)
+			ttm_bo_put(first_bo);
 		return ret;
 	}
 
 	ttm_bo_del_from_lru(bo);
 	spin_unlock(&glob->lru_lock);
+	if (first_bo)
+		ttm_bo_put(first_bo);
 
 	ret = ttm_bo_evict(bo, ctx);
 	if (locked) {
@@ -907,7 +984,7 @@ static int ttm_bo_mem_force_space(struct ttm_buffer_object *bo,
 			return ret;
 		if (mem->mm_node)
 			break;
-		ret = ttm_mem_evict_first(bdev, mem_type, place, ctx);
+		ret = ttm_mem_evict_first(bdev, mem_type, place, ctx, bo->resv);
 		if (unlikely(ret != 0))
 			return ret;
 	} while (1);
@@ -1401,7 +1478,8 @@ static int ttm_bo_force_list_clean(struct ttm_bo_device *bdev,
 	for (i = 0; i < TTM_MAX_BO_PRIORITY; ++i) {
 		while (!list_empty(&man->lru[i])) {
 			spin_unlock(&glob->lru_lock);
-			ret = ttm_mem_evict_first(bdev, mem_type, NULL, &ctx);
+			ret = ttm_mem_evict_first(bdev, mem_type, NULL, &ctx,
+						  NULL);
 			if (ret)
 				return ret;
 			spin_lock(&glob->lru_lock);
@@ -1772,7 +1850,8 @@ 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)) {
+			if (ttm_bo_evict_swapout_allowable(bo, ctx, &locked,
+							   NULL)) {
 				ret = 0;
 				break;
 			}
-- 
2.17.1

_______________________________________________
dri-devel mailing list
dri-devel@lists.freedesktop.org
https://lists.freedesktop.org/mailman/listinfo/dri-devel