Get error when disable /dev/md0: udevd-work[PID]: error opening ATTR{/sys/devices/virtual/block/md0/queue/iosched/quantum} for writing: No such file or directory

Issue

When disable /dev/mdX in RHEL6, it will report error:

-bash-4.1# mdadm -S /dev/md0
md0: detected capacity change from 209702912 to 0
md: md0 stopped.
md: unbind<sdb1>
md: export_rdev(sdb1)
md: unbind<sda1>
md: export_rdev(sda1)
mdadm: stopped /dev/md0
udevd-work[1890]: error opening ATTR{/sys/devices/virtual/block/md0/queue/iosched/slice_idle} for writing: No such file or directory
udevd-work[1890]: error opening ATTR{/sys/devices/virtual/block/md0/queue/iosched/quantum} for writing: No such file or directory
udevd-work[1890]: error opening ATTR{/sys/devices/virtual/block/md0/queue/iosched/slice_idle} for writing: No such file or directory
udevd-work[1890]: error opening ATTR{/sys/devices/virtual/block/md0/queue/iosched/quantum} for writing: No such file or directory