fix grad_output uncontiguous (#737)

* fix grad_output uncontiguous * add comments for uncontiguous

fix grad_output uncontiguous (#737)
* fix grad_output uncontiguous * add comments for uncontiguous
ae982b28 · shilong · GitHub · dedd7994 · ae982b28
Unverified Commit ae982b28 authored Dec 21, 2020 by shilong Committed by GitHub Dec 21, 2020
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mmcv/ops/roi_align.py mmcv/ops/roi_align.py +2 -1

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--- a/mmcv/ops/roi_align.py
+++ b/mmcv/ops/roi_align.py
@@ -94,7 +94,8 @@ class RoIAlignFunction(Function):
    def backward(ctx, grad_output):
        rois, argmax_y, argmax_x = ctx.saved_tensors
        grad_input = grad_output.new_zeros(ctx.input_shape)
-
+        # complex head architecture may cause grad_output uncontiguous.
+        grad_output = grad_output.contiguous()
        ext_module.roi_align_backward(
            grad_output,
            rois,