From: Kirill Tkhai <ktkhai@xxxxxxxxxxxxx> This patch has been added to the 3.12 stable tree. If you have any objections, please let us know. =============== commit eeb61e53ea19be0c4015b00b2e8b3b2185436f2b upstream. The race may happen when somebody is changing task_group of a forking task. Child's cgroup is the same as parent's after dup_task_struct() (there just memory copying). Also, cfs_rq and rt_rq are the same as parent's. But if parent changes its task_group before it's called cgroup_post_fork(), we do not reflect this situation on child. Child's cfs_rq and rt_rq remain the same, while child's task_group changes in cgroup_post_fork(). To fix this we introduce fork() method, which calls sched_move_task() directly. This function changes sched_task_group on appropriate (also its logic has no problem with freshly created tasks, so we shouldn't introduce something special; we are able just to use it). Possibly, this decides the Burke Libbey's problem: https://lkml.org/lkml/2014/10/24/456 Signed-off-by: Kirill Tkhai <ktkhai@xxxxxxxxxxxxx> Signed-off-by: Peter Zijlstra (Intel) <peterz@xxxxxxxxxxxxx> Cc: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx> Link: http://lkml.kernel.org/r/1414405105.19914.169.camel@tkhai Signed-off-by: Ingo Molnar <mingo@xxxxxxxxxx> Signed-off-by: Jiri Slaby <jslaby@xxxxxxx> --- kernel/sched/core.c | 6 ++++++ 1 file changed, 6 insertions(+) diff --git a/kernel/sched/core.c b/kernel/sched/core.c index 3800316d7424..7381119ec1e9 100644 --- a/kernel/sched/core.c +++ b/kernel/sched/core.c @@ -7233,6 +7233,11 @@ static void cpu_cgroup_css_offline(struct cgroup_subsys_state *css) sched_offline_group(tg); } +static void cpu_cgroup_fork(struct task_struct *task) +{ + sched_move_task(task); +} + static int cpu_cgroup_can_attach(struct cgroup_subsys_state *css, struct cgroup_taskset *tset) { @@ -7602,6 +7607,7 @@ struct cgroup_subsys cpu_cgroup_subsys = { .css_free = cpu_cgroup_css_free, .css_online = cpu_cgroup_css_online, .css_offline = cpu_cgroup_css_offline, + .fork = cpu_cgroup_fork, .can_attach = cpu_cgroup_can_attach, .attach = cpu_cgroup_attach, .exit = cpu_cgroup_exit, -- 2.7.4 -- To unsubscribe from this list: send the line "unsubscribe stable" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html