Fixes #10554.
Fixes #10623.

Change-Id: I90fbaa34e3d55c8758178f8d2e7fa41ff1194a1b
Signed-off-by: Shenghou Ma <minux@golang.org>
Reviewed-on: https://go-review.googlesource.com/9247Reviewed-by: Dmitry Vyukov <dvyukov@google.com>
Reviewed-by: Dave Cheney <dave@cheney.net>