2017-01-20 20:37 GMT-03:00 Guillermo:
>
> [...] I'll do more testing during the weekend.
And here are the results:
> 1) Programs from at least util-linux get confused by the way
> system-manager(8) mounts some of the filesystems from
> source/api_mounts.cpp. The problem seems to be those whose
> corresponding array of iovecs doesn't have a 'from' element, which
> IIUC results in a mount(2) call for them with an empty string as the
> 'source' argument in source/nmount.cpp.
It's definitely that. To see what happens, I added lines of the form:
FROM, MAKE_IOVEC("Some non-empty source, even if it is meaningless for
this filesystem's type"),
to each array of iovecs in source/api_mounts.cpp that didn't have one
(inside the #if defined(__LINUX__) || defined(__linux__) ... #else
block), and that does make the other programs happy:
$ mount
/dev/sda4 on / type ext4 (rw,relatime,data=ordered)
proc on /proc type proc (rw,nosuid,nodev,relatime)
sysfs on /sys type sysfs (rw,nosuid,nodev,noexec,relatime)
tmpfs on /sys/fs/cgroup type tmpfs
(rw,nosuid,nodev,noexec,relatime,size=1024k,mode=755)
cgroup on /sys/fs/cgroup/systemd type cgroup
(rw,nosuid,nodev,noexec,relatime,name=systemd)
dev on /dev type devtmpfs (rw,nosuid,size=10240k,nr_inodes=128775,mode=755)
devpts on /dev/pts type devpts (rw,nosuid,noexec,gid=5,mode=620,ptmxmode=666)
tmpfs on /run type tmpfs (rw,nosuid,nodev,size=206124k,mode=755)
tmpfs on /run/shm type tmpfs (rw,nosuid,nodev,noexec,size=515312k)
[...]
$ findmnt --list
TARGET SOURCE FSTYPE OPTIONS
/ /dev/sda4 ext4 rw,relatime,data=ordered
/proc proc proc rw,nosuid,nodev,relatime
/sys sysfs sysfs rw,nosuid,nodev,noexec,relatime
/sys/fs/cgroup tmpfs tmpfs
rw,nosuid,nodev,noexec,relatime,size=1024k,mode=755
/sys/fs/cgroup/systemd cgroup cgroup
rw,nosuid,nodev,noexec,relatime,name=systemd
/dev dev devtmpfs
rw,nosuid,size=10240k,nr_inodes=128775,mode=755
/dev/pts devpts devpts
rw,nosuid,noexec,gid=5,mode=620,ptmxmode=666
/run tmpfs tmpfs rw,nosuid,nodev,size=206124k,mode=755
/run/shm tmpfs tmpfs rw,nosuid,nodev,noexec,size=515312k
[...]
> 2) [...]
> /sys/fs/cgroup shows up empty even though the kernel has cgroups v1
> support compiled in. And the catch-all logger reports this:
>
> $ tai64nlocal /run/system-manager/log/current
> 2017-01-19 21:36:21.771835085 system-manager: INFO: cg1: Not required
> by this kernel.
> 2017-01-19 21:36:21.771907685 system-manager: INFO: sc1: Not required
> by this kernel.
> [...]
> The lines about cg1 and sc1, the arrays of iovecs corresponding to
> /sys/fs/cgroup (fstype=tmpfs) and /sys/fs/cgroup/systemd
> (fstype=cgroup), shouldn't be there, since there is a 'cgroup' line in
> /proc/filesystems that query_control_group_level() in
> source/common-manager.cpp should have seen:
Well, it turns out the explanation wasn't that complicated:
query_control_group_level() tries to read /proc/filesystems, which is
only available after mounting /proc... and /proc is mounted in
setup_kernel_api_volumes_and_devices(), by the code that loops over
the api_mounts vector, *after* calling query_control_group_level(), so
that function unconditionally returns 0 because it can't read the
file. For testing purposes I modified the code to do the dirty trick
of triggering the query_control_group_level() call when an api_mount
object with a 'cgl' field of 3 shows up (and some std::fprintf() calls
to make system-manager more verbose so I could check the results) to
get past this and see what I really wanted to check out in the first
place: system-manager's cgroups v1 setup and its interaction with
set-control-group-knob(1) :)
$ tai64nlocal /run/system-manager/log/current
2017-01-21 22:11:17.709571254 system-manager: INFO: proc: has cgl = 0
2017-01-21 22:11:17.709633263 system-manager: INFO: sys: has cgl = 3
2017-01-21 22:11:17.709637174 system-manager: INFO:
query_control_group_level() returned 1
2017-01-21 22:11:17.709641144 system-manager: INFO: cg1: has cgl = 1
2017-01-21 22:11:17.709644536 system-manager: INFO: sc1: has cgl = 1
2017-01-21 22:11:17.709647934 system-manager: INFO: cg2: has cgl = 2
2017-01-21 22:11:17.709651209 system-manager: INFO: cg2: Not required
by this kernel.
2017-01-21 22:11:17.709654884 system-manager: INFO: sc2: has cgl = 2
2017-01-21 22:11:17.709658104 system-manager: INFO: sc2: Not required
by this kernel.
2017-01-21 22:11:17.709661871 system-manager: INFO: dev: has cgl = 0
2017-01-21 22:11:17.709665114 system-manager: INFO: pts: has cgl = 0
2017-01-21 22:11:17.709668389 system-manager: INFO: run: has cgl = 0
2017-01-21 22:11:17.709671634 system-manager: INFO: shm: has cgl = 0
2017-01-21 22:11:17.709674891 system-manager: ERROR: symlink:
/dev/ptmx: File exists
2017-01-21 22:11:17.709678664 system-manager: ERROR:
/sys/fs/cgroup/systemd//cgroup.subtree_control: No such file or
directory
2017-01-21 22:11:17.709683364 system-manager: ERROR:
/sys/fs/cgroup/systemd//service-manager.slice/cgroup.subtree_control:
No such file or directory
2017-01-21 22:11:17.709688663 system-manager: INFO: system-control
(pid 61) started (init )
2017-01-21 22:11:17.709692514 system-manager: INFO: cyclog (pid 62) started
2017-01-21 22:11:17.709695970 system-manager: INFO: service-manager
(pid 63) started
2017-01-21 22:11:17.735193005 system-manager: INFO: system-control
(pid 61) ended status 0
2017-01-21 22:11:17.735941678 system-manager: INFO: system-control
(pid 64) started (start sysinit)
[...]
$ ps -e -o pid,ppid,comm,cgroup
PID PPID COMMAND CGROUP
1 0 system-manager 1:name=systemd:/me.slice
[...]
62 1 cyclog 1:name=systemd:/system-manager-log.slice
63 1 service-manager 1:name=systemd:/service-manager.slice/me.slice
73 63 udevd 1:name=systemd:/service-manager.slice/eudev.service
113 63 login
1:name=systemd:/service-manager.slice/agetty_at_.service/agetty_at_tty1.service
115 113 bash
1:name=systemd:/service-manager.slice/agetty_at_.service/agetty_at_tty1.service
131 115 ps
1:name=systemd:/service-manager.slice/agetty_at_.service/agetty_at_tty1.service
$ ls /sys/fs/cgroup/systemd/*
/sys/fs/cgroup/systemd/cgroup.clone_children
/sys/fs/cgroup/systemd/cgroup.procs
/sys/fs/cgroup/systemd/cgroup.sane_behavior
/sys/fs/cgroup/systemd/notify_on_release
/sys/fs/cgroup/systemd/release_agent
/sys/fs/cgroup/systemd/tasks
/sys/fs/cgroup/systemd/me.slice:
cgroup.clone_children
cgroup.procs
notify_on_release
tasks
/sys/fs/cgroup/systemd/service-manager.slice:
agetty_at_.service
basic.target
cgroup.clone_children
cgroup.procs
eudev.service
frame-buffer.target
fs-servers.target
local-fs-pre.target
local-fs.target
local-syslog.target
me.slice
multi-user-pre.target
multi-user.target
normal.target
notify_on_release
remote-fs-pre.target
remote-fs.target
server.target
static-networking.target
swapauto.target
swaplate.target
sysinit.target
tasks
uhidd.target
workstation.target
/sys/fs/cgroup/systemd/system-control.slice:
cgroup.clone_children
cgroup.procs
notify_on_release
tasks
/sys/fs/cgroup/systemd/system-manager-log.slice:
cgroup.clone_children
cgroup.procs
notify_on_release
tasks
G.
Received on Sun Jan 22 2017 - 17:29:15 UTC
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