diff --git a/mlir/lib/Dialect/Linalg/Transforms/Vectorization.cpp b/mlir/lib/Dialect/Linalg/Transforms/Vectorization.cpp
--- a/mlir/lib/Dialect/Linalg/Transforms/Vectorization.cpp
+++ b/mlir/lib/Dialect/Linalg/Transforms/Vectorization.cpp
@@ -756,13 +756,14 @@
   // 4 . Check if the operation is a reduction.
   SmallVector<std::pair<Value, Value>> reductionOperands;
   for (Value operand : op->getOperands()) {
-    auto arg = operand.dyn_cast<BlockArgument>();
-    if (!arg || arg.getArgNumber() < linalgOp.getNumDpsInputs())
+    auto blockArg = operand.dyn_cast<BlockArgument>();
+    if (!blockArg || blockArg.getOwner() != linalgOp.getBlock() ||
+        blockArg.getArgNumber() < linalgOp.getNumDpsInputs())
       continue;
     SmallVector<Operation *> reductionOps;
     Value reduceValue = matchReduction(
         linalgOp.getRegionOutputArgs(),
-        arg.getArgNumber() - linalgOp.getNumDpsInputs(), reductionOps);
+        blockArg.getArgNumber() - linalgOp.getNumDpsInputs(), reductionOps);
     if (!reduceValue)
       continue;
     reductionOperands.push_back(std::make_pair(reduceValue, operand));