From: Oleg Nesterov <oleg@redhat.com>
To: Kirill Tkhai <ktkhai@parallels.com>
Cc: linux-kernel@vger.kernel.org,
Peter Zijlstra <peterz@infradead.org>,
Ingo Molnar <mingo@redhat.com>,
Burke Libbey <burke.libbey@shopify.com>,
Vladimir Davydov <vdavydov@parallels.com>,
Kirill Tkhai <tkhai@yandex.ru>
Subject: Re: [PATCH] sched: Fix race between task_group and sched_task_group
Date: Tue, 28 Oct 2014 00:04:27 +0100 [thread overview]
Message-ID: <20141027230427.GA18454@redhat.com> (raw)
In-Reply-To: <1414405105.19914.169.camel@tkhai>
On 10/27, Kirill Tkhai wrote:
>
> +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,
Agreed, but it seems that sched_move_task() -> task_css_check() can
complain if CONFIG_PROVE_RCU...
cpu_cgroup_exit() too calls sched_move_task() without any lock, but
there is the PF_EXITING check and init_css_set can't go away.
perhaps sched_move_task() should just take rcu_read_lock() and use
task_css() ? This lockdep_is_held(siglock) looks ugly, and iiuc we
need it to shut up the warning if autogroup_move_group() is the caller.
Oleg.
next prev parent reply other threads:[~2014-10-27 22:08 UTC|newest]
Thread overview: 14+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-10-27 10:18 [PATCH] sched: Fix race between task_group and sched_task_group Kirill Tkhai
2014-10-27 12:21 ` Peter Zijlstra
2014-10-27 23:04 ` Oleg Nesterov [this message]
2014-10-28 5:24 ` Kirill Tkhai
2014-10-28 22:52 ` Oleg Nesterov
2014-10-29 3:20 ` Kirill Tkhai
2014-10-29 9:16 ` Peter Zijlstra
2014-10-29 11:13 ` Kirill Tkhai
2014-10-29 19:21 ` Oleg Nesterov
2014-11-04 16:07 ` [tip:sched/urgent] sched: Remove lockdep check in sched_move_task () tip-bot for Kirill Tkhai
2014-10-28 11:01 ` [tip:sched/core] sched: Fix race between task_group and sched_task_group tip-bot for Kirill Tkhai
2015-01-26 23:46 ` [PATCH] " Sasha Levin
2015-01-27 8:48 ` Peter Zijlstra
2015-01-27 9:31 ` Peter Zijlstra
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