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  1. Apr 08, 2014
    • Tejun Heo's avatar
      cgroup: newly created dirs and files should be owned by the creator · 49957f8e
      Tejun Heo authored
      
      
      While converting cgroup to kernfs, 2bd59d48 ("cgroup: convert to
      kernfs") accidentally dropped the logic which makes newly created
      cgroup dirs and files owned by the current uid / gid.  This broke
      cases where cgroup subtree management is delegated to !root as the sub
      manager wouldn't be able to create more than single level of hierarchy
      or put tasks into child cgroups it created.
      
      Among other things, this breaks user session management in systemd and
      one of the symptoms was 90s hang during shutdown.  User session
      systemd running as the user creates a sub-service to initiate shutdown
      and tries to put kill(1) into it but fails because cgroup.procs is
      owned by root.  This leads to 90s hang during shutdown.
      
      Implement cgroup_kn_set_ugid() which sets a kn's uid and gid to those
      of the caller and use it from file and dir creation paths.
      
      Signed-off-by: default avatarTejun Heo <tj@kernel.org>
      Reported-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
      49957f8e
  2. Apr 04, 2014