Greeting,

FYI, we noticed the following commit (built with gcc-9):

commit: 13f0f97539f654419d844e6f11766fc7f9c4baf5 ("[PATCH 1/2] percpu_ref: reduce memory footprint of percpu_ref in fast path")
url: https://github.com/0day-ci/linux/commits/Ming-Lei/percpu_ref-block-reduce-memory-footprint-of-percpu_ref-in-fast-path/20200825-181448
base: https://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git bcf876870b95592b52519ed4aafcf9d95999bc9c

in testcase: blktests
with following parameters:

	disk: 1HDD
	test: block-027
	ucode: 0x7000019



on test machine: 16 threads Intel(R) Xeon(R) CPU D-1541 @ 2.10GHz with 48G memory

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



If you fix the issue, kindly add following tag
Reported-by: kernel test robot <lkp@intel.com>


2020-08-31 04:03:36 echo block/027
2020-08-31 04:03:36 mount -t cgroup2 none /sys/fs/cgroup
2020-08-31 04:03:36 ./check block/027
block/027 (stress device hotplugging with running fio jobs and different schedulers)
block/027 (stress device hotplugging with running fio jobs and different schedulers) [failed]
    runtime  ...  17.154s
    something found in dmesg:
    [   45.216600] run blktests block/027 at 2020-08-31 04:03:36
    [   45.242886] scsi host6: scsi_debug: version 0189 [20200421]
                     dev_size_mb=8, opts=0x0, submit_queues=1, statistics=0
    [   45.256436] scsi 6:0:0:0: Direct-Access     Linux    scsi_debug       0189 PQ: 0 ANSI: 7
    [   45.265404] scsi 6:0:0:1: Direct-Access     Linux    scsi_debug       0189 PQ: 0 ANSI: 7
    [   45.274419] scsi 6:0:0:2: Direct-Access     Linux    scsi_debug       0189 PQ: 0 ANSI: 7
    [   45.283358] scsi 6:0:0:3: Direct-Access     Linux    scsi_debug       0189 PQ: 0 ANSI: 7
    [   45.292341] scsi 6:0:0:4: Direct-Access     Linux    scsi_debug       0189 PQ: 0 ANSI: 7
    [   45.301339] scsi 6:0:0:5: Direct-Access     Linux    scsi_debug       0189 PQ: 0 ANSI: 7
    [   45.310357] scsi 6:0:0:6: Direct-Access     Linux    scsi_debug       0189 PQ: 0 ANSI: 7
    ...
    (See '/lkp/benchmarks/blktests/results/nodev/block/027.dmesg' for the entire message)


To reproduce:

        git clone https://github.com/intel/lkp-tests.git
        cd lkp-tests
        bin/lkp install job.yaml  # job file is attached in this email
        bin/lkp run     job.yaml



Thanks,
lkp