Remove _check_large_shapes checking in fmha/ck.py (#1067)

xformers/ops/fmha/ck.py

@@ -102,21 +102,6 @@ def _check_bias_alignment(
             )
 
 
-def _check_large_shapes(reasons: List[str], inp: Inputs) -> None:
-    """CK kernel throws "Memory access fault by GPU node-2" when B * T >= 2**20, might be some index overflow.
-    To reproduce, remove this function and run benchmark_mem_eff_attention with ParlAI model shape (256, 4096, 16, 64).
-    This needs further debugging, for now let's not support such shapes.
-    """
-    b_t_limit = 1024**2
-    q_too_large = inp.query.shape[0] * inp.query.shape[1] >= b_t_limit
-    k_too_large = inp.key.shape[0] * inp.key.shape[1] >= b_t_limit
-    v_too_large = inp.value.shape[0] * inp.value.shape[1] >= b_t_limit
-    if q_too_large or k_too_large or v_too_large:
-        reasons.append(
-            "Input is too large: product of first two dimensions of q/k/v must be < 2**20"
-        )
-
-
 class _CustomMaskType(int, Enum):
     """
     (Matches CustomMaskType in C++.)
@@ -325,7 +310,6 @@ def not_supported_reasons(cls, d: Inputs) -> List[str]:
         check_lastdim_alignment_stride1(reasons, "query", d.query, matmul_alignment_mn)
         check_lastdim_alignment_stride1(reasons, "value", d.value, matmul_alignment_mn)
         _check_bias_alignment(reasons, d.attn_bias)
-        _check_large_shapes(reasons, d)
         return reasons
 
     @classmethod
@@ -416,7 +400,6 @@ def not_supported_reasons(cls, d: Inputs) -> List[str]:
                     f"(shape: {tuple(attn_bias_tensor.shape)}"
                     f"/ expected: {expected_bias_shape})"
                 )
-        _check_large_shapes(reasons, d)
 
         return reasons