[VROC]Call trace during IO on IMSM RAID 5 (fio performance check)

[quanxian]

Description

There is a call trace during fio testing of IMSM RAID 5 array. Call trace is attached.

How reproducible: always (after few hours of fio testing)

Steps to Reproduce:
1. Create IMSM RAID5 with 4 disks:
mdadm -C /dev/md/imsm0 -n 4 -e imsm /dev/nvme0n1 /dev/nvme1n1 /dev/nvme2n1 /dev/nvme3n1
mdadm -C /dev/md126 /dev/md/imsm0 -n4 -l 5 -c 64 -f
2. Increase number of RAID5 threads:
echo 4 > /sys/block/md126/md/group_thread_cnt
3. Trigger fio:
fio --time_based --name="fio_check=16=16=4kb=100" --filename=/dev/md126 --rw=randrw --rwmixwrite=100 --bs=4kb --direct=1 --do_verify=0 --eta=never --iodepth=16 --ioengine=libaio --runtime=600 --ramp_time=600 --refill_buffers --numjobs=16 --group_reporting --randrepeat=0 --thread --unified_rw_reporting=1 --cpus_allowed=2-17 --cpus_allowed_policy=split --disable_lat=1 --disable_slat=1 --disable_bw=1 --stonewall --norandommap --minimal --output=results_16_16_4kb_100.log

Target Kernel: TBD
Target Release: 19.10

[quanxian (quanxian-wang)]

if reproduce, just reopen it.