From fd7e15b76d4c655ceaa8f8c89c1bd0e4a81a561e Mon Sep 17 00:00:00 2001
From: Cheng Wan <54331508+ch-wan@users.noreply.github.com>
Date: Fri, 8 Aug 2025 21:34:17 -0700
Subject: [PATCH] Revert "[bug fix] Ensure local token and global token buffers
 are pointing to different storage " (#8993)

---
 python/sglang/srt/layers/dp_attention.py | 14 ++++++--------
 1 file changed, 6 insertions(+), 8 deletions(-)
 mode change 100755 => 100644 python/sglang/srt/layers/dp_attention.py

diff --git a/python/sglang/srt/layers/dp_attention.py b/python/sglang/srt/layers/dp_attention.py
old mode 100755
new mode 100644
index 2e53befc6..79397cce5
--- a/python/sglang/srt/layers/dp_attention.py
+++ b/python/sglang/srt/layers/dp_attention.py
@@ -264,10 +264,9 @@ def _dp_gather_via_all_reduce(
     assert global_tokens.is_contiguous()
 
     if local_tokens.shape[0] > 0 and (is_partial or get_attention_tp_rank() == 0):
-        if local_tokens.untyped_storage() is global_tokens.untyped_storage():
-            # dp_gather is an in-place operation and requires input and output tensors to not be aliased.
-            # so we create a separate buffer if they share the same storage.
-            global_tokens = torch.empty_like(global_tokens)
+        assert (
+            local_tokens.untyped_storage() is not global_tokens.untyped_storage()
+        ), "aliasing between global_tokens and local_tokens not allowed"
 
         memcpy_triton(
             global_tokens, local_tokens, 0, local_start_pos, local_num_tokens, False
@@ -348,10 +347,9 @@ def dp_scatter(
     assert local_tokens.is_contiguous()
     assert global_tokens.is_contiguous()
     if local_tokens.shape[0] > 0:
-        if local_tokens.untyped_storage() is global_tokens.untyped_storage():
-            # dp_scatter is an in-place operation and requires input and output tensors to not be aliased.
-            # so we create a separate buffer if they share the same storage.
-            local_tokens = torch.empty_like(local_tokens)
+        assert (
+            local_tokens.untyped_storage() is not global_tokens.untyped_storage()
+        ), "aliasing between local_tokens and global_tokens not allowed"
 
         memcpy_triton(
             local_tokens, global_tokens, 0, local_start_pos, local_num_tokens, True