no fa3 with attention mask (#163)

* no fa3 with attention mask

* modify log level for fla attn_mask

---------

Co-authored-by: qufei.qf <qufei.qf@alibaba-inc.com>

Author: akaitsuki-ii

diffsynth_engine/models/basic/attention.py

@@ -135,12 +135,13 @@ def attention(
     flash_attn3_compatible = q.shape[-1] <= FA3_MAX_HEADDIM
     if attn_impl is None or attn_impl == "auto":
         if FLASH_ATTN_3_AVAILABLE:
-            if flash_attn3_compatible:
+            if flash_attn3_compatible and attn_mask is None:
                 return flash_attn3(q, k, v, softmax_scale=scale)
             else:
-                logger.warning(
-                    f"head_dim={q.shape[-1]}, but flash_attn_3 only supports head dimension at most {FA3_MAX_HEADDIM}, will use fallback attention implementation"
-                )
+                if not flash_attn3_compatible:
+                    logger.warning(f"head_dim={q.shape[-1]}, but flash_attn_3 only supports head dimension at most {FA3_MAX_HEADDIM}, will use fallback attention implementation")
+                else:
+                    logger.debug("flash_attn_3 does not support attention mask, will use fallback attention implementation")
         if XFORMERS_AVAILABLE:
             return xformers_attn(q, k, v, attn_mask=attn_mask, scale=scale)
         if SDPA_AVAILABLE:
@@ -156,6 +157,8 @@ def attention(
                 raise RuntimeError(
                     f"head_dim={q.shape[-1]}, but flash_attn_3 only supports head dimension at most {FA3_MAX_HEADDIM}"
                 )
+            if attn_mask is not None:
+                raise RuntimeError("flash_attn_3 does not support attention mask")
             return flash_attn3(q, k, v, softmax_scale=scale)
         if attn_impl == "flash_attn_2":
             return flash_attn2(q, k, v, softmax_scale=scale)