xfstest warning on all tests when running with memory debugging in kernel config

[Steve French <smfrench@xxxxxxxxx>]

Running with kmemdebug on in the kernel config  I get this warning
before and after all non-skipped xfstests

Any idea how to get rid of it?

generic/001 4s ...
./common/rc: line 3491: echo: write error: Device or resource busy
./common/rc: line 3493: echo: write error: Device or resource busy
...

Basically it is doing (which returns an error when debugging enabled
in the kernel).  I am running xfstest as root

echo "scan" > "${DEBUGFS_MNT}/kmemleak"

Ideas?
-- 
Thanks,

Steve