Comment # 24 on bug 1016313 from Franck Bui

Ok, the issue you're facing is probably due to :

> execve("/usr/lib/systemd/systemd-timesyncd", ["/usr/lib/systemd/systemd-timesyn"...], [/* 116 vars */]) = 0
> ...
> statfs("/sys/fs/selinux", 0x7ffec2cac480) = -1 ENOENT (No such file or directory)
> statfs("/selinux", {f_type=BTRFS_SUPER_MAGIC, f_bsize=4096, f_blocks=31204254, f_bfree=29339042, f_bavail=29153112, f_files=0, f_ffree=0, f_fsid={val=[2664197864, 450012966]}, f_namelen=255, f_frsize=4096, f_flags=ST_VALID|ST_NOATIME}) = 0
> mount("proc", "/proc", "proc", 0, NULL) = -1 EBUSY (Device or resource busy)

This call to mount(2) is done when ld is loading and initializing the share
libs used by systemd-timesyncd.

libselinux is one of them and is the one which does the mount(2) syscall.

>From libselinux changelog:

  $ rpm -q libselinux1 
  libselinux1-2.5-2.5.x86_64

  $ rpm -q --changelog libselinux1
  [...]
  * Sun Jul 24 2016 crrodriguez@opensuse.org
  - Avoid mounting /proc outside of selinux_init_load_policy().
    (Stephen Smalley) reverts upstream 5a8d8c4, 9df4988, fixes
    among other things systemd seccomp sandboxing otherwise all
    filters must allow mount(2)
    (libselinux-proc-mount-only-if-needed.patch)
  [...]

So it seems that this issue has been addressed already...

Can you check the version of this lib installed on your system and make sure
that the version you're using includes this fix ?