diff --git a/src/gallium/drivers/d3d12/d3d12_query.cpp b/src/gallium/drivers/d3d12/d3d12_query.cpp
index e58a4f16b12..d821fe819f9 100644
--- a/src/gallium/drivers/d3d12/d3d12_query.cpp
+++ b/src/gallium/drivers/d3d12/d3d12_query.cpp
@@ -203,7 +203,11 @@ accumulate_subresult_cpu(struct d3d12_context *ctx, struct d3d12_query *q_parent
    unsigned access = PIPE_MAP_READ;
    void *results;
 
-   access |= PIPE_MAP_UNSYNCHRONIZED;
+   /* When called from tc_get_query_result on the app thread (flushed query),
+    * the driver thread may be running concurrently. Use PIPE_MAP_THREAD_SAFE
+    * to avoid slab allocator races on transfer_pool.
+    */
+   access |= PIPE_MAP_UNSYNCHRONIZED | PIPE_MAP_THREAD_SAFE;
 
    results = pipe_buffer_map_range(&ctx->base, q->buffer, q->buffer_offset,
                                    q->num_queries * q->query_size,
diff --git a/src/gallium/drivers/d3d12/d3d12_resource.cpp b/src/gallium/drivers/d3d12/d3d12_resource.cpp
index 88be1bce21e..2c4d500537c 100644
--- a/src/gallium/drivers/d3d12/d3d12_resource.cpp
+++ b/src/gallium/drivers/d3d12/d3d12_resource.cpp
@@ -1782,9 +1782,15 @@ d3d12_transfer_map(struct pipe_context *pctx,
    if (usage & PIPE_MAP_DIRECTLY || !res->bo)
       return NULL;
 
-   slab_child_pool* transfer_pool = (usage & TC_TRANSFER_MAP_THREADED_UNSYNC) ?
-      &ctx->transfer_pool_unsync : &ctx->transfer_pool;
-   struct d3d12_transfer *trans = (struct d3d12_transfer *)slab_zalloc(transfer_pool);
+   slab_child_pool* transfer_pool = NULL;
+   struct d3d12_transfer *trans;
+   if (usage & PIPE_MAP_THREAD_SAFE) {
+      trans = (struct d3d12_transfer *)CALLOC_STRUCT(d3d12_transfer);
+   } else {
+      transfer_pool = (usage & TC_TRANSFER_MAP_THREADED_UNSYNC) ?
+         &ctx->transfer_pool_unsync : &ctx->transfer_pool;
+      trans = (struct d3d12_transfer *)slab_zalloc(transfer_pool);
+   }
    struct pipe_transfer *ptrans = &trans->base.b;
    if (!trans)
       return NULL;
@@ -1810,7 +1816,10 @@ d3d12_transfer_map(struct pipe_context *pctx,
 
       range = linear_range(box, ptrans->stride, ptrans->layer_stride);
       if (!synchronize(ctx, res, usage, &range)) {
-         slab_free(transfer_pool, trans);
+         if (usage & PIPE_MAP_THREAD_SAFE)
+            FREE(trans);
+         else
+            slab_free(transfer_pool, trans);
          return NULL;
       }
       ptr = d3d12_bo_map(res->bo, &range);
@@ -1934,7 +1943,10 @@ d3d12_transfer_map(struct pipe_context *pctx,
                                               staging_usage,
                                               staging_res_size);
       if (!trans->staging_res) {
-         slab_free(transfer_pool, trans);
+         if (usage & PIPE_MAP_THREAD_SAFE)
+            FREE(trans);
+         else
+            slab_free(transfer_pool, trans);
          return NULL;
       }
 
@@ -2062,7 +2074,15 @@ d3d12_transfer_unmap(struct pipe_context *pctx,
    }
 
    pipe_resource_reference(&ptrans->resource, NULL);
-   slab_free(&d3d12_context(pctx)->transfer_pool, ptrans);
+   if (ptrans->usage & PIPE_MAP_THREAD_SAFE) {
+      FREE(ptrans);
+   } else {
+      /* transfer_unmap is always called from the driver thread, so we use
+       * transfer_pool, not transfer_pool_unsync.  Freeing an object into a
+       * different pool is allowed, however.
+       */
+      slab_free(&d3d12_context(pctx)->transfer_pool, ptrans);
+   }
 }
 
 void