From: Kirill Tkhai Date: Mon, 27 Oct 2014 10:18:25 +0000 (+0400) Subject: sched: Fix race between task_group and sched_task_group X-Git-Tag: v3.18-rc3~21^2~8 X-Git-Url: https://openfabrics.org/gitweb/?a=commitdiff_plain;h=eeb61e53ea19be0c4015b00b2e8b3b2185436f2b;p=~emulex%2Finfiniband.git sched: Fix race between task_group and sched_task_group 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 Signed-off-by: Peter Zijlstra (Intel) Cc: Linus Torvalds Link: http://lkml.kernel.org/r/1414405105.19914.169.camel@tkhai Signed-off-by: Ingo Molnar --- diff --git a/kernel/sched/core.c b/kernel/sched/core.c index 44999505e1b..dde8adb7d0c 100644 --- a/kernel/sched/core.c +++ b/kernel/sched/core.c @@ -7833,6 +7833,11 @@ 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) { @@ -8205,6 +8210,7 @@ struct cgroup_subsys cpu_cgrp_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,