Hello, Li, Frederic. On Mon, Oct 08, 2012 at 01:46:18PM +0800, Li Zefan wrote: > You're right. threadgroup lock is held unconditionally in attach_task_py_pid(), > but it's held only for CLONE_THREAD in fork path, which I guess I overlooked > when reviewing the patch. > > > Also, please note that task_lock is likely to be hot on local CPU at > > that point and avoiding it there might not really buy much. > > Reverting that commit should be fine. There are other commits which perform similar optimization 7e3aa30ac8 ("cgroup: Remove task_lock() from cgroup_post_fork()") c84cdf75cc ("cgroup: Remove unnecessary task_lock before fetching css_set on migration") Are they wrong too? 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