Hello, Frederic. On Thu, Oct 18, 2012 at 04:50:59PM +0200, Frederic Weisbecker wrote: > Ah right I was confused. Hmm, indeed we have a race here on > cgroup_fork(). How about using css_try_get() in cgroup_fork() and > refetch the parent's css until we succeed? This requires rcu_read_lock > though, and freeing the css_set under RCU. > > Don't know which is better. For now, I'll revert the patches and cc stable. Let's think about improving it later. > Different problem but I really would like we sanitize the cgroup hooks > in fork. There is cgroup_fork(), cgroup_post_fork() which takes that > big css_set_lock, plus the big threadgroup lock... I hope we can > simplify the mess there. Oh yeah, I've been looking at that one too. There are a few problems in that area. I think all we need is clearing ->cgroups to NULL on copy_process() and all the rest can be moved to cgroup_post_fork(). I'd also like to make it very explicit that migration can't happen before post_fork is complete. > > I really don't know. Why isn't it locking the threadgroup to begin > > with? > > No idea, sounds like something to fix. Alrighty. Thanks. -- tejun -- To unsubscribe from this list: send the line "unsubscribe cgroups" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
