Eric Lee / smarc-fsl-linux-kernel

26 Jul, 2008

1 commit

  • e885dcde7   cgroup_clone: use pid of newly created task for new cgroup ... Browse Code »

    cgroup_clone creates a new cgroup with the pid of the task. This works
    correctly for unshare, but for clone cgroup_clone is called from
    copy_namespaces inside copy_process, which happens before the new pid is
    created. As a result, the new cgroup was created with current's pid.
    This patch:

    1. Moves the call inside copy_process to after the new pid
    is created
    2. Passes the struct pid into ns_cgroup_clone (as it is not
    yet attached to the task)
    3. Passes a name from ns_cgroup_clone() into cgroup_clone()
    so as to keep cgroup_clone() itself simpler
    4. Uses pid_vnr() to get the process id value, so that the
    pid used to name the new cgroup is always the pid as it
    would be known to the task which did the cloning or
    unsharing. I think that is the most intuitive thing to
    do. This way, task t1 does clone(CLONE_NEWPID) to get
    t2, which does clone(CLONE_NEWPID) to get t3, then the
    cgroup for t3 will be named for the pid by which t2 knows
    t3.

    (Thanks to Dan Smith for finding the main bug)

    Changelog:
    June 11: Incorporate Paul Menage's feedback: don't pass
    NULL to ns_cgroup_clone from unshare, and reduce
    patch size by using 'nodename' in cgroup_clone.
    June 10: Original version

    [akpm@linux-foundation.org: build fix]
    [akpm@linux-foundation.org: coding-style fixes]
    Signed-off-by: Serge Hallyn
    Acked-by: Paul Menage
    Tested-by: Dan Smith
    Cc: Balbir Singh
    Cc: KAMEZAWA Hiroyuki
    Signed-off-by: Andrew Morton
    Signed-off-by: Linus Torvalds

    Serge E. Hallyn
     

29 Apr, 2008

2 commits

20 Oct, 2007

1 commit

  • 858d72ead   cgroups: implement namespace tracking subsystem ... Browse Code »

    When a task enters a new namespace via a clone() or unshare(), a new cgroup
    is created and the task moves into it.

    This version names cgroups which are automatically created using
    cgroup_clone() as "node_" where pid is the pid of the unsharing or
    cloned process. (Thanks Pavel for the idea) This is safe because if the
    process unshares again, it will create

    /cgroups/(...)/node_/node_

    The only possibilities (AFAICT) for a -EEXIST on unshare are

    1. pid wraparound
    2. a process fails an unshare, then tries again.

    Case 1 is unlikely enough that I ignore it (at least for now). In case 2, the
    node_ will be empty and can be rmdir'ed to make the subsequent unshare()
    succeed.

    Changelog:
    Name cloned cgroups as "node_".

    [clg@fr.ibm.com: fix order of cgroup subsystems in init/Kconfig]
    Signed-off-by: Serge E. Hallyn
    Cc: Paul Menage
    Signed-off-by: Cedric Le Goater
    Signed-off-by: Andrew Morton
    Signed-off-by: Linus Torvalds

    Serge E. Hallyn