[lkml]   [2014]   [Mar]   [25]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
Messages in this thread
    Patch in this message
    Subject[PATCH 3.8 40/81] cgroup: update cgroup_enable_task_cg_lists() to grab siglock
    Date -stable review patch.  If anyone has any objections, please let me know.


    From: Tejun Heo <>

    commit 532de3fc72adc2a6525c4d53c07bf81e1732083d upstream.

    Currently, there's nothing preventing cgroup_enable_task_cg_lists()
    from missing set PF_EXITING and race against cgroup_exit(). Depending
    on the timing, cgroup_exit() may finish with the task still linked on
    css_set leading to list corruption. Fix it by grabbing siglock in
    cgroup_enable_task_cg_lists() so that PF_EXITING is guaranteed to be

    This whole on-demand cg_list optimization is extremely fragile and has
    ample possibility to lead to bugs which can cause things like
    once-a-year oops during boot. I'm wondering whether the better
    approach would be just adding "cgroup_disable=all" handling which
    disables the whole cgroup rather than tempting fate with this
    on-demand craziness.

    Signed-off-by: Tejun Heo <>
    Acked-by: Li Zefan <>
    Signed-off-by: Kamal Mostafa <>
    kernel/cgroup.c | 5 +++++
    1 file changed, 5 insertions(+)

    diff --git a/kernel/cgroup.c b/kernel/cgroup.c
    index ba9e28c..a2d2c80 100644
    --- a/kernel/cgroup.c
    +++ b/kernel/cgroup.c
    @@ -2982,9 +2982,14 @@ static void cgroup_enable_task_cg_lists(void)
    * We should check if the process is exiting, otherwise
    * it will race with cgroup_exit() in that the list
    * entry won't be deleted though the process has exited.
    + * Do it while holding siglock so that we don't end up
    + * racing against cgroup_exit().
    + spin_lock_irq(&p->sighand->siglock);
    if (!(p->flags & PF_EXITING) && list_empty(&p->cg_list))
    list_add(&p->cg_list, &p->cgroups->tasks);
    + spin_unlock_irq(&p->sighand->siglock);
    } while_each_thread(g, p);

     \ /
      Last update: 2014-03-25 19:21    [W:5.214 / U:0.020 seconds]
    ©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site