Re: [Suggestion] kernel: cgroup: mount failure in LTP cgroup_regression_test.sh

[Jan Stancek <jstancek-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>]

Hi,

it looks like those 2 subsystems are already mounted by systemd,
each in different hierarchy:

>   cpuacct	4	35	1
>   freezer	5	4	1

from Documentation/cgroups/cgroups.txt:
"If an active hierarchy with exactly the same set of subsystems already
exists, it will be reused for the new mount. If no existing hierarchy
matches, and any of the requested subsystems are in use in an existing
hierarchy, the mount will fail with -EBUSY. Otherwise, a new hierarchy
is activated, associated with the requested subsystems."

Regards,
Jan

----- Original Message -----
> From: "Chen Gang" <gang.chen.5i5j-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>
> To: "Tejun Heo" <tj-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org>, "Garrett Cooper" <yanegomi-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>, gaowanlong-BthXqXjhjHXQFUHtdCDX3A@public.gmane.org, chris-8NJIiSa5LzA@public.gmane.org,
> jstancek-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org, mitani-Czb31pHLG9l3+QwDJ9on6Q@public.gmane.org, lizf-BthXqXjhjHXQFUHtdCDX3A@public.gmane.org
> Cc: "Li Zefan" <lizefan-hv44wF8Li93QT0dZR+AlfA@public.gmane.org>, containers-cunTk1MwBs9QetFLy7KEm3xJsTq8ys+cHZ5vskTnxNA@public.gmane.org, cgroups-u79uwXL29TY76Z2rM5mHXA@public.gmane.org
> Sent: Thursday, 21 November, 2013 5:18:50 AM
> Subject: Fwd: [Suggestion] kernel: cgroup: mount failure in LTP cgroup_regression_test.sh
> 
> Hello LTP maintainers:
> 
> When I use ltp to test cgroup, I find one failure, the related forward
> mail is below.
> 
> Related LTP git commit is "75df824 Add cgroup regression tests to LTP:
> Those testcases can reproduce bugs we found in cgroups, and is useful
> to track future regressions." (lizf-BthXqXjhjHXQFUHtdCDX3A@public.gmane.org and subrata_modak)
> 
> Please help check when you have time.
> 
> Thanks.
> 
> -------- Original Message --------
> Subject: [Suggestion] kernel: cgroup: mount failure in LTP
> cgroup_regression_test.sh
> Date: Fri, 08 Nov 2013 16:15:23 +0800
> From: Chen Gang <gang.chen-bOixZGp5f+dBDgjK7y7TUQ@public.gmane.org>
> To: Tejun Heo <tj-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org>, Li Zefan <lizefan-hv44wF8Li93QT0dZR+AlfA@public.gmane.org>
> CC: containers-cunTk1MwBs9QetFLy7KEm3xJsTq8ys+cHZ5vskTnxNA@public.gmane.org, cgroups-u79uwXL29TY76Z2rM5mHXA@public.gmane.org,
> "linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org" <linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org>
> 
> Hello Maintainers:
> 
> On Fedora16 with defconfig for next-20131107 kernel, use latest LTP
> (Linux Test Project) version, test_5() in cgroup_regression_test.sh
> will be fail. The related LTP output:
> 
>   <<<test_start>>>
>   tag=cgroup stime=1383562810
>   cmdline="       cgroup_regression_test.sh"
>   contacts=""
>   analysis=exit
>   <<<test_output>>>
>   cgroup_regression_test    1  TPASS  :  no kernel bug was found
>   /opt/ltp/testcases/bin/cgroup_regression_test.sh: line 118: 13283
>   Terminated              ./fork_processes
>   cgroup_regression_test    2  TPASS  :  notify_on_release is inherited
>   cgroup_regression_test    3  TCONF  :  CONFIG_SCHED_DEBUG is not enabled
>   cgroup_regression_test    4  TCONF  :  CONFIG_LOCKDEP is not enabled
>   mount: xxx already mounted or cgroup/ busy
>   cgroup_regression_test    5  TFAIL  :  mount freezer and cpuacct failed
>   cgroup_regression_test    6  TCONF  :  CONFIG_CGROUP_NS
>   /opt/ltp/testcases/bin/cgroup_regression_test.sh: line 360: 24428
>   Terminated              sleep 100 < cgroup/0
>   /opt/ltp/testcases/bin/cgroup_regression_test.sh: line 381: 24447
>   Terminated              sleep 100 < cgroup/0
>   cgroup_regression_test    7  TPASS  :  no kernel bug was found
>   cgroup_regression_test    8  TPASS  :  no kernel bug was found
>   cgroup_regression_test    9  TPASS  :  no kernel warning was found
>   rmdir: failed to remove `cgroup/0': No such file or directory
>   umount: /sys/fs/cgroup/systemd: device is busy.
>           (In some cases useful info about processes that use
>            the device is found by lsof(8) or fuser(1))
>   cgroup_regression_test   10  TPASS  :  no kernel warning was found
>   <<<execution_status>>>
>   initiation_status="ok"
>   duration=62 termination_type=exited termination_id=1 corefile=no
>   cutime=3341 cstime=6353
>   <<<test_end>>>
> 
> After simplify, the related operation, environments and output are:
> 
>   [root@gchenlinux tmp]# df -Th | grep cgroup
>   tmpfs                             tmpfs    1001M     0 1001M   0%
>   /sys/fs/cgroup
>   [root@gchenlinux tmp]# lsof | grep cgroup | grep -v grep
>   systemd       1          root    6r      DIR               0,18         0
>   5998 /sys/fs/cgroup/systemd/system
>   [root@gchenlinux tmp]# cat /proc/cgroups
>   #subsys_name	hierarchy	num_cgroups	enabled
>   cpuset	3	4	1
>   cpu	4	35	1
>   cpuacct	4	35	1
>   freezer	5	4	1
>   [root@gchenlinux tmp]# mkdir cgroup
>   [root@gchenlinux tmp]# mount -t cgroup -o freezer,cpuacct xxx cgroup/
>   mount: xxx already mounted or cgroup/ busy
> 
> Is it real issue of cgroup? If it is, I will/should continue analyzing.
> 
> 
> Welcome any additional suggestions and completions.
> 
> Thanks.
> --
> Chen Gang
> 
> 
>