test: harden CP HiCache metadata invariants

python/sglang/srt/mem_cache/hiradix_cache.py

@@ -64,8 +64,12 @@ class CpHiCacheNodeMetadata:
     def __post_init__(self):
         if self.logical_len < 0:
             raise ValueError(f"logical_len must be non-negative, got {self.logical_len}")
-        self.owned_positions = self.owned_positions.to(device="cpu", dtype=torch.int64)
-        self.host_indices = self.host_indices.to(device="cpu", dtype=torch.int64)
+        self.owned_positions = self.owned_positions.to(
+            device="cpu", dtype=torch.int64
+        ).detach().clone()
+        self.host_indices = self.host_indices.to(
+            device="cpu", dtype=torch.int64
+        ).detach().clone()
         if self.owned_positions.numel() != self.host_indices.numel():
             raise ValueError(
                 "owned_positions and host_indices must have same length, got "
@@ -76,8 +80,10 @@ class CpHiCacheNodeMetadata:
                 self.owned_positions >= self.logical_len
             ):
                 raise ValueError("owned_positions must be in [0, logical_len)")
-            if torch.any(self.owned_positions[1:] < self.owned_positions[:-1]):
-                raise ValueError("owned_positions must be sorted")
+            if torch.any(self.owned_positions[1:] <= self.owned_positions[:-1]):
+                raise ValueError(
+                    "owned_positions must be sorted and strictly increasing"
+                )
 
     def split(
         self, split_len: int

test/registered/unit/mem_cache/test_cp_hicache_metadata.py

@@ -1,6 +1,6 @@
 import sys
 import unittest
-from unittest.mock import MagicMock, patch
+from unittest.mock import MagicMock
 
 import torch
 
@@ -10,8 +10,7 @@ for _mod in ("sgl_kernel", "sgl_kernel.kvcacheio"):
     if _mod not in sys.modules:
         sys.modules[_mod] = MagicMock()
 
-from sglang.srt.mem_cache.hiradix_cache import CpHiCacheNodeMetadata, HiRadixCache
-from sglang.srt.mem_cache.radix_cache import RadixKey, TreeNode
+from sglang.srt.mem_cache.hiradix_cache import CpHiCacheNodeMetadata
 from sglang.test.ci.ci_register import register_cpu_ci
 from sglang.test.test_utils import CustomTestCase
 
@@ -62,6 +61,21 @@ class TestCpHiCacheNodeMetadata(CustomTestCase):
         self.assertEqual(metadata.owned_positions.device.type, "cpu")
         self.assertEqual(metadata.host_indices.device.type, "cpu")
 
+    def test_metadata_does_not_alias_input_tensors(self):
+        owned_positions = torch.tensor([1, 3], dtype=torch.int64)
+        host_indices = torch.tensor([10, 11], dtype=torch.int64)
+
+        metadata = CpHiCacheNodeMetadata(
+            logical_len=4,
+            owned_positions=owned_positions,
+            host_indices=host_indices,
+        )
+        owned_positions[0] = 2
+        host_indices[0] = 12
+
+        self.assertEqual(metadata.owned_positions.tolist(), [1, 3])
+        self.assertEqual(metadata.host_indices.tolist(), [10, 11])
+
     def test_invalid_split_raises(self):
         metadata = CpHiCacheNodeMetadata(
             logical_len=4,
@@ -80,6 +94,14 @@ class TestCpHiCacheNodeMetadata(CustomTestCase):
                 host_indices=torch.tensor([9, 10], dtype=torch.int64),
             )
 
+    def test_duplicate_positions_raise(self):
+        with self.assertRaisesRegex(ValueError, "strictly increasing"):
+            CpHiCacheNodeMetadata(
+                logical_len=4,
+                owned_positions=torch.tensor([1, 1], dtype=torch.int64),
+                host_indices=torch.tensor([9, 10], dtype=torch.int64),
+            )
+
     def test_length_mismatch_raises(self):
         with self.assertRaisesRegex(ValueError, "same length"):
             CpHiCacheNodeMetadata(