[BugFix][LoRA] use adapter_id instead of id field of lora_request (#27728)

Signed-off-by: Biswa Panda <biswa.panda@gmail.com>

tests/v1/core/test_prefix_caching.py

@@ -9,7 +9,8 @@ import pytest
 import torch
 
 import vllm.v1.core.kv_cache_utils as kv_cache_utils
-from vllm.distributed.kv_events import AllBlocksCleared, BlockRemoved
+from vllm.distributed.kv_events import AllBlocksCleared, BlockRemoved, BlockStored
+from vllm.lora.request import LoRARequest
 from vllm.multimodal.inputs import (
     MultiModalFeatureSpec,
     MultiModalKwargsItem,
@@ -59,6 +60,7 @@ def make_request(
     mm_hashes: list[str] | None = None,
     prompt_logprobs: int | None = None,
     cache_salt: str | None = None,
+    lora_request: LoRARequest | None = None,
 ):
     mm_features = []
     if mm_positions is not None:
@@ -79,7 +81,7 @@ def make_request(
         sampling_params=SamplingParams(max_tokens=17, prompt_logprobs=prompt_logprobs),
         pooling_params=None,
         eos_token_id=100,
-        lora_request=None,
+        lora_request=lora_request,
         cache_salt=cache_salt,
         block_hasher=get_request_block_hasher(block_size, hash_fn),
     )
@@ -1337,6 +1339,63 @@ def test_kv_cache_events(blocks_to_cache: int):
     assert len(manager.block_pool.cached_block_hash_to_block) == 0
 
 
+@pytest.mark.parametrize("blocks_to_cache", [2, 3, 10])
+def test_kv_cache_events_with_lora(blocks_to_cache: int):
+    """Test BlockStored events contain correct lora_id when using LoRA requests."""
+    block_size = 16
+    num_blocks = blocks_to_cache + 1
+
+    # Create KVCacheManager with events enabled
+    manager = KVCacheManager(
+        make_kv_cache_config(block_size, num_blocks),
+        max_model_len=8192,
+        enable_caching=True,
+        enable_kv_cache_events=True,
+    )
+
+    # Test with LoRA request
+    lora_request = LoRARequest(
+        lora_name="test_lora", lora_int_id=42, lora_path="/test/path"
+    )
+
+    num_tokens = block_size * blocks_to_cache
+    req_with_lora = make_request(
+        "lora_req",
+        list(range(num_tokens)),
+        block_size,
+        sha256,
+        lora_request=lora_request,
+    )
+
+    # Allocate slots and get events
+    _ = manager.allocate_slots(req_with_lora, num_tokens)
+    events = manager.take_events()
+
+    # Verify BlockStored event contains correct lora_id
+    block_stored_event = events[-1]
+    assert isinstance(block_stored_event, BlockStored)
+    assert block_stored_event.lora_id == 42  # Should match lora_request.adapter_id
+    assert len(block_stored_event.block_hashes) == blocks_to_cache
+    assert block_stored_event.block_size == block_size
+
+    # Clean up
+    manager.free(req_with_lora)
+
+    # Test without LoRA request (should have lora_id=None)
+    req_without_lora = make_request(
+        "no_lora_req", list(range(num_tokens)), block_size, sha256
+    )
+
+    _ = manager.allocate_slots(req_without_lora, num_tokens)
+    events = manager.take_events()
+
+    block_stored_event = events[-1]
+    assert isinstance(block_stored_event, BlockStored)
+    assert block_stored_event.lora_id is None  # Should be None when no LoRA request
+    assert len(block_stored_event.block_hashes) == blocks_to_cache
+    assert block_stored_event.block_size == block_size
+
+
 def test_eagle_enabled_removes_last_block():
     """Verify Eagle does NOT remove blocks when request
     length is divisible by block size."""

vllm/v1/core/block_pool.py

@@ -259,7 +259,9 @@ class BlockPool:
                         num_cached_blocks * block_size : num_full_blocks * block_size
                     ],
                     block_size=block_size,
-                    lora_id=request.lora_request.id if request.lora_request else None,
+                    lora_id=request.lora_request.adapter_id
+                    if request.lora_request
+                    else None,
                     medium=MEDIUM_GPU,
                 )
             )