On Sat, Feb 4, 2017 at 12:20 AM, Max Yehorov <myehorov@xxxxxxxxxx> wrote:
> It is certainly annoying. It does not allow to umount for hours.
For hours? Does it succeed after X number of hours?
>> Does umount error out or hang forever?
> umount errors out. with
> umount: target is busy
> (In some cases useful info about processes that
> use the device is found by lsof(8) or fuser(1).)
>
> Maybe this will help?
>
> - lsof, for the rbd device in question, shows it is in use by pid 5926
>
> dio/rbd0 5926 root cwd DIR 8,5 4096 2 /
> dio/rbd0 5926 root rtd DIR 8,5 4096 2 /
> dio/rbd0 5926 root txt unknown /proc/5926/exe
This doesn't say that /dev/rbd0 is in use by pid 5926. It says that
there is a process with the name "dio/rbd0", that's all.
I'm guessing you ran plain "lsof" with no arguments here. Were there
other */rbd0 matches, like jbd2/rbd0?
>
> - PID 5926 is dio, it seems like a kernel thread
> ps ax | grep 5926
> 5926 ? S< 0:00 [dio/rbd0]
>
> - Also, there is no more dio but that one
> ps ax | grep dio
> 5926 ? S< 0:00 [dio/rbd0]
It's a kernel workqueue, its presence itself doesn't mean much:
$ sudo mkfs.ext4 /dev/rbd0
...
$ sudo mount /dev/rbd0 /mnt
$ pgrep -a dio # nothing
$ sudo fio --ioengine=libaio --direct=1 --name=test
--filename=/mnt/test --bs=4k --size=16M --readwrite=randwrite
...
$ pgrep -a dio
1254 dio/rbd0
$ ps 1254
PID TTY STAT TIME COMMAND
1254 ? S< 0:00 [dio/rbd0]
$ sudo umount /mnt # OK
Thanks,
Ilya
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