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    SubjectRe: [PATCH 0/8 v3] cgroups: Task counter subsystem (was: New max number of tasks subsystem)
    On Mon, Aug 1, 2011 at 4:19 PM, Andrew Morton <akpm@linux-foundation.org> wrote:
    > On Fri, 29 Jul 2011 18:13:22 +0200
    > Frederic Weisbecker <fweisbec@gmail.com> wrote:
    >
    >> Reminder:
    >>
    >> This patchset is aimed at reducing the impact of a forkbomb to a
    >> cgroup boundaries, thus minimizing the consequences of such an attack
    >> against the rest of the system.
    >>
    >> This can be useful when cgroups are used to stage some processes or run
    >> untrustees.
    >
    > Really?  How useful?  Why is it useful enough to justify adding code
    > such as this to the kernel?
    >
    > Is forkbomb-prevention the only use?  Others have proposed different
    > ways of preventing forkbombs which were independent of cgroups - is
    > this way better and if so, why?

    I certainly want this for exactly the proposed use - putting a bounds
    on threads/tasks per container. It's rlimits but more useful.

    IMHO, most every limit that can be set at a system level should be
    settable at a cgroup level. This is just one more isolation leak.

    >>  block/blk-cgroup.c            |   10 ++-
    >>  include/linux/cgroup.h        |   15 +++-
    >>  include/linux/cgroup_subsys.h |    8 ++
    >>  include/linux/res_counter.h   |   12 +++
    >>  init/Kconfig                  |    7 ++
    >>  kernel/Makefile               |    1 +
    >>  kernel/cgroup.c               |   25 ++++--
    >>  kernel/cgroup_freezer.c       |    3 +-
    >>  kernel/cgroup_task_counter.c  |  176 +++++++++++++++++++++++++++++++++++++++++
    >>  kernel/cpuset.c               |    6 +-
    >>  kernel/events/core.c          |    5 +-
    >>  kernel/fork.c                 |    4 +
    >>  kernel/res_counter.c          |   81 ++++++++++++++++---
    >>  kernel/sched.c                |    6 +-
    >
    > The patch forgot to document the feature: how it works, what it's
    > useful for, what behaviour users can expect to see, when they should
    > consider using it, what the userspace control interface is and how to
    > configure it, etc.  Documentation/cgroups/ is the place for that.

    +1 - I am not very familiar with the cgroups code, so I am disinclined
    to learn it all just to evaluate the functionality and API of this
    patch. Design doc, please?

    Tim
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