[Bugfix] Restrict TRTLLM attention to SM100, fixing GB300 (SM103) hang (#38730)

Signed-off-by: Stefano Castagnetta <scastagnetta@nvidia.com>
(cherry picked from commit 6183cae1bd)

docs/design/attention_backends.md

@@ -167,7 +167,7 @@ Priority is **1 = highest** (tried first).
 | ------- | ------- | ------ | --------- | ----------- | ---------- | ---- | --------- | --- | --------------- | ------------ |
 | `CPU_ATTN` | | fp16, bf16, fp32 | `auto` | Any | 32, 64, 80, 96, 112, 128, 160, 192, 224, 256 | ❌ | ❌ | ❌ | All | N/A |
 | `FLASHINFER` | Native† | fp16, bf16 | `auto`, `float16`, `bfloat16`, `fp8`, `fp8_e4m3`, `fp8_e5m2` | 16, 32, 64 | 64, 128, 256 | ❌ | ❌ | ✅ | Decoder | 7.x-9.x |
-| `FLASHINFER` | TRTLLM† | fp16, bf16 | `auto`, `float16`, `bfloat16`, `fp8`, `fp8_e4m3`, `fp8_e5m2` | 16, 32, 64 | 64, 128, 256 | ✅ | ❌ | ✅ | Decoder | 10.x |
+| `FLASHINFER` | TRTLLM† | fp16, bf16 | `auto`, `float16`, `bfloat16`, `fp8`, `fp8_e4m3`, `fp8_e5m2` | 16, 32, 64 | 64, 128, 256 | ✅ | ❌ | ✅ | Decoder | 10.0 |
 | `FLASH_ATTN` | FA2* | fp16, bf16 | `auto`, `float16`, `bfloat16` | %16 | Any | ❌ | ❌ | ✅ | All | ≥8.0 |
 | `FLASH_ATTN` | FA3* | fp16, bf16 | `auto`, `float16`, `bfloat16`, `fp8`, `fp8_e4m3`, `fp8_e5m2` | %16 | Any | ✅ | ❌ | ✅ | All | 9.x |
 | `FLASH_ATTN` | FA4* | fp16, bf16 | `auto`, `float16`, `bfloat16` | %16 | Any | ❌ | ❌ | ✅ | All | ≥10.0 |

docs/features/reasoning_outputs.md

@@ -244,12 +244,12 @@ response = client.chat.completions.create(
 
 Some models, such as [Qwen3](https://qwen.readthedocs.io/en/latest/getting_started/quickstart.html#thinking-budget), [DeepSeek](https://www.alibabacloud.com/help/en/model-studio/deep-thinking), and [Nemotron3](https://huggingface.co/nvidia/NVIDIA-Nemotron-3-Nano-30B-A3B-BF16), support a thinking budget that limits the maximum number of tokens used for reasoning.
 
-Token counting starts from `think_start_str`. Once the reasoning token count reaches the configured `thinking_token_budget`, vLLM forces the model to produce `think_end_str`, effectively terminating the reasoning block.
+Token counting starts from `reasoning_start_str`. Once the reasoning token count reaches the configured `thinking_token_budget`, vLLM forces the model to produce `reasoning_end_str`, effectively terminating the reasoning block.
 
 To use this feature:
 
 - `--reasoning-parser` enables reasoning extraction.
-- `--reasoning-config` defines the reasoning boundary tokens (e.g., `think_start_str`, `think_end_str`).
+- `--reasoning-config` defines the reasoning boundary tokens (e.g., `reasoning_start_str`, `reasoning_end_str`).
 - `thinking_token_budget` (a sampling parameter) sets the per-request reasoning token limit.
 
 If `thinking_token_budget` is not specified, no explicit reasoning limit is applied beyond normal generation constraints such as `max_tokens`.
@@ -257,20 +257,20 @@ If `thinking_token_budget` is not specified, no explicit reasoning limit is appl
 `--reasoning-config` accepts a JSON object corresponding to  
 [ReasoningConfig][vllm.config.ReasoningConfig] with the following fields:
 
-| Field             | Type           | Description                                      |
+| Field                 | Type           | Description                                      |
-|-------------------|----------------|--------------------------------------------------|
+|-----------------------|----------------|--------------------------------------------------|
-| `think_start_str` | `str \| null`  | String that marks the start of reasoning content |
+| `reasoning_start_str` | `str \| null`  | String that marks the start of reasoning content |
-| `think_end_str`   | `str \| null`  | String that marks the end of reasoning content   |
+| `reasoning_end_str`   | `str \| null`  | String that marks the end of reasoning content   |
 
 !!! note
-    `think_end_str` can include a transition phrase before the think end token. For example, setting `think_end_str` to `"I have to give the solution based on the thinking directly now.</think>"` instructs the model to emit that phrase when the budget is exhausted, making the reasoning termination more natural.
+    `reasoning_end_str` can include a transition phrase before the reasoning end token. For example, setting `reasoning_end_str` to `"I have to give the solution based on the reasoning directly now.</think>"` instructs the model to emit that phrase when the budget is exhausted, making the reasoning termination more natural.
 
 ### Online Serving
 
 ```bash
 vllm serve Qwen/Qwen3-0.6B \
     --reasoning-parser qwen3 \
-    --reasoning-config '{"think_start_str": "<think>", "think_end_str": "I have to give the solution based on the thinking directly now.</think>"}'
+    --reasoning-config '{"reasoning_start_str": "<think>", "reasoning_end_str": "I have to give the solution based on the reasoning directly now.</think>"}'
 ```
 
 Then make a request with `thinking_token_budget` to limit the reasoning tokens:
@@ -298,8 +298,8 @@ from vllm.config import ReasoningConfig
 llm = LLM(
     model="Qwen/Qwen3-0.6B",
     reasoning_config=ReasoningConfig(
-        think_start_str="<think>",
+        reasoning_start_str="<think>",
-        think_end_str="I have to give the solution based on the thinking directly now.</think>",
+        reasoning_end_str="I have to give the solution based on the thinking directly now.</think>",
     ),
 )
 

tests/multimodal/media/test_video.py

@@ -239,6 +239,17 @@ def test_video_media_io_backend_env_var_fallback(monkeypatch: pytest.MonkeyPatch
         assert metadata_missing["video_backend"] == "test_video_backend_override_2"
 
 
+def _make_jpeg_b64_frames(n: int, width: int = 8, height: int = 8) -> list[str]:
+    """Return *n* tiny base64-encoded JPEG frames."""
+    frames: list[str] = []
+    for i in range(n):
+        img = Image.new("RGB", (width, height), color=(i % 256, 0, 0))
+        buf = io.BytesIO()
+        img.save(buf, format="JPEG")
+        frames.append(pybase64.b64encode(buf.getvalue()).decode("ascii"))
+    return frames
+
+
 def test_load_base64_jpeg_returns_metadata():
     """Regression test: load_base64 with video/jpeg must return metadata.
 
@@ -248,16 +259,8 @@ def test_load_base64_jpeg_returns_metadata():
     """
 
     num_test_frames = 3
-    frame_width, frame_height = 8, 8
-
-    # Build a few tiny JPEG frames and base64-encode them
-    b64_frames = []
-    for i in range(num_test_frames):
-        img = Image.new("RGB", (frame_width, frame_height), color=(i * 80, 0, 0))
-        buf = io.BytesIO()
-        img.save(buf, format="JPEG")
-        b64_frames.append(pybase64.b64encode(buf.getvalue()).decode("ascii"))
 
+    b64_frames = _make_jpeg_b64_frames(num_test_frames)
     data = ",".join(b64_frames)
 
     imageio = ImageMediaIO()
@@ -287,3 +290,52 @@ def test_load_base64_jpeg_returns_metadata():
     # Default fps=1 → duration == num_frames
     assert metadata["fps"] == 1.0
     assert metadata["duration"] == float(num_test_frames)
+
+
+def test_load_base64_jpeg_enforces_num_frames_limit():
+    """Frames beyond num_frames must be truncated in the video/jpeg path.
+
+    Without the limit an attacker can send thousands of base64 JPEG frames
+    in a single request and exhaust server memory (OOM).
+    """
+    num_frames_limit = 4
+    sent_frames = 20
+
+    b64_frames = _make_jpeg_b64_frames(sent_frames)
+    data = ",".join(b64_frames)
+
+    imageio = ImageMediaIO()
+    videoio = VideoMediaIO(imageio, num_frames=num_frames_limit)
+    frames, metadata = videoio.load_base64("video/jpeg", data)
+
+    assert frames.shape[0] == num_frames_limit
+    assert metadata["total_num_frames"] == num_frames_limit
+    assert metadata["frames_indices"] == list(range(num_frames_limit))
+
+
+def test_load_base64_jpeg_no_limit_when_num_frames_negative():
+    """When num_frames is -1, all frames should be loaded without truncation."""
+    sent_frames = 10
+
+    b64_frames = _make_jpeg_b64_frames(sent_frames)
+    data = ",".join(b64_frames)
+
+    imageio = ImageMediaIO()
+    videoio = VideoMediaIO(imageio, num_frames=-1)
+    frames, metadata = videoio.load_base64("video/jpeg", data)
+
+    assert frames.shape[0] == sent_frames
+    assert metadata["total_num_frames"] == sent_frames
+    assert metadata["frames_indices"] == list(range(sent_frames))
+
+
+def test_load_base64_jpeg_raises_on_zero_num_frames():
+    """num_frames=0 is invalid and should raise ValueError."""
+    b64_frames = _make_jpeg_b64_frames(3)
+    data = ",".join(b64_frames)
+
+    imageio = ImageMediaIO()
+    videoio = VideoMediaIO(imageio, num_frames=0)
+
+    with pytest.raises(ValueError, match="num_frames must be greater than 0 or -1"):
+        videoio.load_base64("video/jpeg", data)

tests/v1/entrypoints/openai/test_thinking_token_budget.py

@@ -20,7 +20,7 @@ def server():
         "--reasoning-parser",
         "qwen3",
         "--reasoning-config",
-        '{"think_start_str": "<think>", "think_end_str": "</think>"}',
+        '{"reasoning_start_str": "<think>", "reasoning_end_str": "</think>"}',
         "--max-model-len",
         "2048",
         "--enforce-eager",

tests/v1/logits_processors/test_correctness.py

@@ -103,8 +103,8 @@ class LogitsProcsRequestParams:
 class MockReasoningConfig:
     """Mock reasoning config for testing ThinkingTokenBudgetLogitsProcessor."""
 
-    think_start_token_ids = [THINK_START_TOKEN_ID]
+    reasoning_start_token_ids = [THINK_START_TOKEN_ID]
-    think_end_token_ids = [THINK_END_TOKEN_ID]
+    reasoning_end_token_ids = [THINK_END_TOKEN_ID]
 
 
 def _generate_fake_sampling_metadata(
@@ -491,7 +491,7 @@ def _thinking_budget_validate(
 
         # Find if thinking has started in output tokens
         thinking_started = False
-        start_tokens = tb_processor.think_start_token_ids
+        start_tokens = tb_processor.reasoning_start_token_ids
 
         if len(start_tokens) > 0:
             for i in range(len(output_tokens) - len(start_tokens) + 1):
@@ -518,7 +518,7 @@ def _thinking_budget_validate(
                     )
 
                 # Validate that only end tokens are allowed
-                end_tokens = tb_processor.think_end_token_ids
+                end_tokens = tb_processor.reasoning_end_token_ids
                 if len(end_tokens) > 0:
                     expected_end_token_id = end_tokens[
                         min(state["end_count"], len(end_tokens) - 1)

tools/pre_commit/generate_attention_backend_docs.py

@@ -235,10 +235,11 @@ def _resolve_import_to_file(
 
 
 def _find_cc_in_function(tree: ast.AST, func_name: str) -> str | None:
-    """Find a compute capability from is_device_capability_family() calls in a function.
+    """Find a compute capability from is_device_capability*() calls in a function.
 
-    Looks for the pattern: current_platform.is_device_capability_family(N)
+    Handles two patterns:
-    and converts N (e.g. 100) to a CC string (e.g. "10.x").
+    - is_device_capability_family(N): "M.x" (e.g. 100 -> "10.x")
+    - is_device_capability(N): "M.m" (e.g. 100 -> "10.0")
     """
     for node in ast.walk(tree):
         if not isinstance(node, ast.FunctionDef) or node.name != func_name:
@@ -247,12 +248,15 @@ def _find_cc_in_function(tree: ast.AST, func_name: str) -> str | None:
             if (
                 isinstance(n, ast.Call)
                 and isinstance(n.func, ast.Attribute)
-                and n.func.attr == "is_device_capability_family"
                 and n.args
                 and isinstance(n.args[0], ast.Constant)
                 and isinstance(n.args[0].value, int)
             ):
-                return f"{n.args[0].value // 10}.x"
+                val = n.args[0].value
+                if n.func.attr == "is_device_capability_family":
+                    return f"{val // 10}.x"
+                elif n.func.attr == "is_device_capability":
+                    return f"{val // 10}.{val % 10}"
     return None
 
 

vllm/config/reasoning.py

@@ -12,7 +12,7 @@ from vllm.tokenizers import cached_tokenizer_from_config
 class ReasoningConfig:
     """Configuration for reasoning models.
 
-    Set `think_start_str` and `think_end_str` to the strings that delimit
+    Set `reasoning_start_str` and `reasoning_end_str` to the strings that delimit
     the reasoning block (e.g. `"<think>"` and `"</think>"`).  The
     corresponding token IDs are derived automatically via
     `initialize_token_ids` and are not intended to be set directly.
@@ -20,53 +20,55 @@ class ReasoningConfig:
 
     # NOTE: These parameters are temporary, the intent is to derive them
     # automatically from the reasoning parser in a future version.
-    think_start_str: str = "<think>"
+    reasoning_start_str: str = "<think>"
     """String that indicates the start of reasoning."""
-    think_end_str: str = "</think>"
+    reasoning_end_str: str = "</think>"
     """String that indicates the end of reasoning content."""
 
-    _think_start_token_ids: list[int] | None = field(
+    _reasoning_start_token_ids: list[int] | None = field(
         default=None, init=False, repr=False
     )
-    """Private backing field for `think_start_token_ids`. Set by
+    """Private backing field for `reasoning_start_token_ids`. Set by
     `initialize_token_ids`. Not intended to be configured directly."""
-    _think_end_token_ids: list[int] | None = field(default=None, init=False, repr=False)
+    _reasoning_end_token_ids: list[int] | None = field(
-    """Private backing field for `think_end_token_ids`. Set by
+        default=None, init=False, repr=False
+    )
+    """Private backing field for `reasoning_end_token_ids`. Set by
     `initialize_token_ids`. Not intended to be configured directly."""
 
     @property
-    def think_start_token_ids(self) -> list[int] | None:
+    def reasoning_start_token_ids(self) -> list[int] | None:
-        """Token IDs derived from `think_start_str`. Set automatically by
+        """Token IDs derived from `reasoning_start_str`. Set automatically by
         `initialize_token_ids`. Not intended to be configured directly."""
-        return self._think_start_token_ids
+        return self._reasoning_start_token_ids
 
     @property
-    def think_end_token_ids(self) -> list[int] | None:
+    def reasoning_end_token_ids(self) -> list[int] | None:
-        """Token IDs derived from `think_end_str`. Set automatically by
+        """Token IDs derived from `reasoning_end_str`. Set automatically by
         `initialize_token_ids`. Not intended to be configured directly."""
-        return self._think_end_token_ids
+        return self._reasoning_end_token_ids
 
     def initialize_token_ids(self, model_config: ModelConfig) -> None:
         """Initialize reasoning token IDs from strings using the tokenizer."""
         if (
-            self._think_start_token_ids is not None
+            self._reasoning_start_token_ids is not None
-            and self._think_end_token_ids is not None
+            and self._reasoning_end_token_ids is not None
         ):
             return
 
         tokenizer = cached_tokenizer_from_config(model_config=model_config)
 
-        self._think_start_token_ids = tokenizer.encode(
+        self._reasoning_start_token_ids = tokenizer.encode(
-            self.think_start_str, add_special_tokens=False
+            self.reasoning_start_str, add_special_tokens=False
         )
-        self._think_end_token_ids = tokenizer.encode(
+        self._reasoning_end_token_ids = tokenizer.encode(
-            self.think_end_str, add_special_tokens=False
+            self.reasoning_end_str, add_special_tokens=False
         )
 
-        if not self._think_start_token_ids or not self._think_end_token_ids:
+        if not self._reasoning_start_token_ids or not self._reasoning_end_token_ids:
             raise ValueError(
                 f"ReasoningConfig: failed to tokenize reasoning strings: "
-                f"think_start_str='{self.think_start_str}', "
+                f"reasoning_start_str='{self.reasoning_start_str}', "
-                f"think_end_str='{self.think_end_str}'. "
+                f"reasoning_end_str='{self.reasoning_end_str}'. "
                 "Ensure the strings are valid tokens in the model's vocabulary."
             )

vllm/multimodal/media/video.py

@@ -80,8 +80,15 @@ class VideoMediaIO(MediaIO[tuple[npt.NDArray, dict[str, Any]]]):
                 "image/jpeg",
             )
 
+            if self.num_frames > 0:
+                frame_parts = data.split(",", self.num_frames)[: self.num_frames]
+            elif self.num_frames == 0:
+                raise ValueError("num_frames must be greater than 0 or -1")
+            else:
+                frame_parts = data.split(",")
+
             frames = np.stack(
-                [np.asarray(load_frame(frame_data)) for frame_data in data.split(",")]
+                [np.asarray(load_frame(frame_data)) for frame_data in frame_parts]
             )
             total = int(frames.shape[0])
             fps = float(self.kwargs.get("fps", 1))

vllm/utils/flashinfer.py

@@ -289,10 +289,10 @@ def supports_trtllm_attention() -> bool:
     if envs.VLLM_BATCH_INVARIANT:
         return False
 
-    # Requires SM100 and NVIDIA artifactory to be accessible to download cubins
+    # TRTLLM attention is currently only validated on SM100 (CC 10.0).
-    return (
+    # SM103 (GB300) hangs with FlashInfer >= 0.6.7.
-        current_platform.is_device_capability_family(100) and has_nvidia_artifactory()
+    # See: https://github.com/flashinfer-ai/flashinfer/issues/2939
-    )
+    return current_platform.is_device_capability(100) and has_nvidia_artifactory()
 
 
 def force_use_trtllm_attention() -> bool | None:

vllm/v1/sample/logits_processor/builtin.py

@@ -303,10 +303,12 @@ class ThinkingTokenBudgetLogitsProcessor(LogitsProcessor):
         # Check if thinking is enabled
         self.is_enabled = reasoning_config is not None
 
-        self.think_start_token_ids = getattr(
+        self.reasoning_start_token_ids = getattr(
-            reasoning_config, "think_start_token_ids", []
+            reasoning_config, "reasoning_start_token_ids", []
+        )
+        self.reasoning_end_token_ids = getattr(
+            reasoning_config, "reasoning_end_token_ids", []
         )
-        self.think_end_token_ids = getattr(reasoning_config, "think_end_token_ids", [])
 
         self.pin_memory = is_pin_memory
         self.device = device
@@ -357,15 +359,15 @@ class ThinkingTokenBudgetLogitsProcessor(LogitsProcessor):
             think_count = 0
         else:
             last_start = self._find_last_sequence_index(
-                prompt_tok_ids, self.think_start_token_ids
+                prompt_tok_ids, self.reasoning_start_token_ids
             )
             last_end = self._find_last_sequence_index(
-                prompt_tok_ids, self.think_end_token_ids
+                prompt_tok_ids, self.reasoning_end_token_ids
             )
             in_think = last_start > last_end
             if in_think:
                 think_count = len(prompt_tok_ids) - (
-                    last_start + len(self.think_start_token_ids)
+                    last_start + len(self.reasoning_start_token_ids)
                 )
             else:
                 think_count = 0
@@ -405,8 +407,8 @@ class ThinkingTokenBudgetLogitsProcessor(LogitsProcessor):
         state["prev_output_length"] = current_length
 
         # Check if new tokens contain think start or end sequences
-        start_len = len(self.think_start_token_ids)
+        start_len = len(self.reasoning_start_token_ids)
-        end_len = len(self.think_end_token_ids)
+        end_len = len(self.reasoning_end_token_ids)
 
         # Look for think sequences in recent tokens (including boundary)
         # Check overlapping regions where sequences might span boundaries
@@ -415,10 +417,10 @@ class ThinkingTokenBudgetLogitsProcessor(LogitsProcessor):
 
         # Find any think start/end sequences in recent tokens
         recent_start_pos = self._find_last_sequence_index(
-            recent_tokens, self.think_start_token_ids
+            recent_tokens, self.reasoning_start_token_ids
         )
         recent_end_pos = self._find_last_sequence_index(
-            recent_tokens, self.think_end_token_ids
+            recent_tokens, self.reasoning_end_token_ids
         )
 
         # Update state based on recent sequences
@@ -469,7 +471,7 @@ class ThinkingTokenBudgetLogitsProcessor(LogitsProcessor):
         else:
             # In end mode
             state["end_count"] += 1
-            if state["end_count"] >= len(self.think_end_token_ids):
+            if state["end_count"] >= len(self.reasoning_end_token_ids):
                 state.update(
                     {
                         "in_end": False,
@@ -530,7 +532,9 @@ class ThinkingTokenBudgetLogitsProcessor(LogitsProcessor):
             state = self._state.get(i)
             if state and state["in_end"]:
                 self.mask[i] = True
-                self.force_token_ids[i] = self.think_end_token_ids[state["end_count"]]
+                self.force_token_ids[i] = self.reasoning_end_token_ids[
+                    state["end_count"]
+                ]
 
         # Check in CPU first not to sync with GPU
         has_active_thinking = any(