diff --git a/deepinfer/neuron_ops/vendor/deep_ep/buffers/engram.py b/deepinfer/neuron_ops/vendor/deep_ep/buffers/engram.py
index c3d15c9..1555921 100644
--- a/deepinfer/neuron_ops/vendor/deep_ep/buffers/engram.py
+++ b/deepinfer/neuron_ops/vendor/deep_ep/buffers/engram.py
@@ -208,12 +208,18 @@ class EngramBuffer(BufferBase):
 
     def _shared(self, name: str, rows: int, row_bytes: int) -> torch.Tensor:
         """A ``[rows, row_bytes]`` uint8 tensor mapping one /dev/shm file shared by the group's ranks."""
-        # Ranks of one job share their launcher: its pid names the job.
-        path = f"/dev/shm/deepinfer_engram_{os.getppid()}_{name}"
+        # One name for the whole group: rank 0 publishes its pid through the distributed store. (The parent pid is not
+        # shared: CP followers are children of their engine's driver, not of the launcher.)
+        store = dist.distributed_c10d._get_default_store()
+        key = f"deepinfer_engram_shm_{name}"
         if self.rank_idx == 0:
+            path = f"/dev/shm/deepinfer_engram_{os.getpid()}_{name}"
             with open(path, "wb") as f:
                 f.truncate(rows * row_bytes)
+            store.set(key, path)
         comm.barrier(self)
+        path = store.get(key).decode()
+        assert os.path.getsize(path) == rows * row_bytes, path  # opening must never create a second table
         t = torch.from_file(path, shared=True, size=rows * row_bytes, dtype=torch.uint8).view(rows, row_bytes)
         comm.barrier(self)
         if self.rank_idx == 0: