FYI, we noticed the following commit (built with gcc-7):

commit: b77eab7079d9e477489d2416cceda05d3c1cf21f ("mm/memory_hotplug: optimize probe routine")
https://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git master

in testcase: kernel_selftests
with following parameters:

	group: kselftests-02

test-description: The kernel contains a set of "self tests" under the tools/testing/selftests/ directory. These are intended to be small unit tests to exercise individual code paths in the kernel.
test-url: https://www.kernel.org/doc/Documentation/kselftest.txt


on test machine: 88 threads Intel(R) Xeon(R) CPU E5-2699 v4 @ 2.20GHz with 64G memory

caused below changes (please refer to attached dmesg/kmsg for entire log/backtrace):


2018-04-14 05:44:58 make run_tests -C memory-hotplug
make: Entering directory '/usr/src/linux-selftests-x86_64-rhel-7.2-b77eab7079d9e477489d2416cceda05d3c1cf21f/tools/testing/selftests/memory-hotplug'
Test scope: 2% hotplug memory
	 online all hot-pluggable memory in offline state:
		 SKIPPED - no hot-pluggable memory in offline state
	 offline 2% hot-pluggable memory in online state
	 trying to offline 1 out of 28 memory block(s):
online->offline memory10
	 online all hot-pluggable memory in offline state:
offline->online memory10
./mem-on-off-test.sh: line 70: echo: write error: Device or resource busy
online_memory_expect_success 10: unexpected fail
	 Test with memory notifier error injection
./mem-on-off-test.sh: line 70: echo: write error: Device or resource busy
online_memory_expect_success 10: unexpected fail
selftests: memory-hotplug [FAIL]
make: Leaving directory '/usr/src/linux-selftests-x86_64-rhel-7.2-b77eab7079d9e477489d2416cceda05d3c1cf21f/tools/testing/selftests/memory-hotplug'


Thanks,
Xiaolong