On Mon, Oct 27, 2014 at 04:36:02PM +0300, Kirill Tkhai wrote: > > > 27.10.2014, 16:28, "Peter Zijlstra" <[email protected]>: > > On Mon, Oct 27, 2014 at 08:40:02AM -0400, Tejun Heo wrote: > >> On Mon, Oct 27, 2014 at 01:07:34PM +0100, Peter Zijlstra wrote: > >>> On Fri, Oct 24, 2014 at 09:18:42PM +0400, Kirill Tkhai wrote: > >>>> I was seeking a places where task_group of a task may change. I can't > >>>> understand > >>>> how changing of parent's cgroup during fork() applies to a child. > >>> I didn't know we could change cgroup on fork(), I though the idea was > >>> you always inherited your parents cgroup. > >>> > >>> How can this be? > >> Hmmm? -ENEEDMORECONTEXT but the inheriting happens at one point during > >> fork in cgroup_post_fork(). The child inherits whatever the parent > >> cgroup is at that point. > > > > So Kirill is saying that there is a race between fork and attach such > > that a child can end up in a different cgroup than the parent and we > > need to use the cgroup_subsys::fork call to fix that up. > > I mean cgroup is the same, but sched_task_group is other (sched_task_group > is equal to parent's on the moment of dup_task_struct()).
But that still means the parent changed cgroup during fork right? It started out in a different cgroup than it ended up with, and we need that .fork callback to fixup state. -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
