From: Oleg Nesterov <oleg@redhat.com>
To: "Paul E. McKenney" <paulmck@linux.vnet.ibm.com>
Cc: linux-kernel@vger.kernel.org, mingo@kernel.org,
laijs@cn.fujitsu.com, dipankar@in.ibm.com,
akpm@linux-foundation.org, mathieu.desnoyers@efficios.com,
josh@joshtriplett.org, tglx@linutronix.de, peterz@infradead.org,
rostedt@goodmis.org, dhowells@redhat.com, edumazet@google.com,
dvhart@linux.intel.com, fweisbec@gmail.com,
bobby.prani@gmail.com
Subject: Re: [PATCH v2 tip/core/rcu 01/10] rcu: Add call_rcu_tasks()
Date: Fri, 1 Aug 2014 17:53:10 +0200 [thread overview]
Message-ID: <20140801155310.GA2945@redhat.com> (raw)
In-Reply-To: <1406767182-4356-1-git-send-email-paulmck@linux.vnet.ibm.com>
On 07/30, Paul E. McKenney wrote:
>
> + rcu_read_lock();
> + for_each_process_thread(g, t) {
> + if (t != current && ACCESS_ONCE(t->on_rq) &&
> + !is_idle_task(t)) {
> + t->rcu_tasks_nvcsw = ACCESS_ONCE(t->nvcsw);
> + t->rcu_tasks_holdout = 1;
> + list_add(&t->rcu_tasks_holdout_list,
> + &rcu_tasks_holdouts);
> + }
> + }
> + rcu_read_unlock();
Wait, unless I missed something this can't work...
The problem is, once the exiting task passes exit_notify() it can
be removed from rcu lists.
Now suppose that (say) proc_exit_connector() has a probe, and this
task has jumped into trampoline and it was preempted there.
No?
Oleg.
next prev parent reply other threads:[~2014-08-01 15:55 UTC|newest]
Thread overview: 42+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-07-31 0:39 [PATCH v2 tip/core/rcu 0/10] RCU-tasks implementation Paul E. McKenney
2014-07-31 0:39 ` [PATCH v2 tip/core/rcu 01/10] rcu: Add call_rcu_tasks() Paul E. McKenney
2014-07-31 0:39 ` [PATCH v2 tip/core/rcu 02/10] rcu: Provide cond_resched_rcu_qs() to force quiescent states in long loops Paul E. McKenney
2014-07-31 0:39 ` [PATCH v2 tip/core/rcu 03/10] rcu: Add synchronous grace-period waiting for RCU-tasks Paul E. McKenney
2014-07-31 16:58 ` josh
2014-07-31 18:34 ` Paul E. McKenney
2014-07-31 0:39 ` [PATCH v2 tip/core/rcu 04/10] rcu: Export RCU-tasks APIs to GPL modules Paul E. McKenney
2014-07-31 16:56 ` josh
2014-07-31 20:55 ` Paul E. McKenney
2014-07-31 0:39 ` [PATCH v2 tip/core/rcu 05/10] rcutorture: Add torture tests for RCU-tasks Paul E. McKenney
2014-07-31 17:01 ` josh
2014-07-31 20:55 ` Paul E. McKenney
2014-07-31 0:39 ` [PATCH v2 tip/core/rcu 06/10] rcutorture: Add RCU-tasks test cases Paul E. McKenney
2014-07-31 0:39 ` [PATCH v2 tip/core/rcu 07/10] rcu: Add stall-warning checks for RCU-tasks Paul E. McKenney
2014-07-31 0:39 ` [PATCH v2 tip/core/rcu 08/10] rcu: Improve RCU-tasks energy efficiency Paul E. McKenney
2014-07-31 0:39 ` [PATCH v2 tip/core/rcu 09/10] documentation: Add verbiage on RCU-tasks stall warning messages Paul E. McKenney
2014-07-31 0:39 ` [PATCH v2 tip/core/rcu 10/10] rcu: Make RCU-tasks track exiting tasks Paul E. McKenney
2014-07-31 7:30 ` [PATCH v2 tip/core/rcu 01/10] rcu: Add call_rcu_tasks() Lai Jiangshan
2014-07-31 16:09 ` Paul E. McKenney
2014-07-31 16:20 ` Peter Zijlstra
2014-07-31 16:47 ` Paul E. McKenney
2014-07-31 16:57 ` Peter Zijlstra
2014-07-31 16:31 ` Oleg Nesterov
2014-07-31 17:02 ` Paul E. McKenney
2014-07-31 17:27 ` Oleg Nesterov
2014-07-31 17:44 ` Paul E. McKenney
2014-08-01 0:53 ` Lai Jiangshan
2014-08-01 2:09 ` Paul E. McKenney
2014-08-01 15:53 ` Oleg Nesterov [this message]
2014-08-01 18:19 ` Paul E. McKenney
2014-08-01 18:36 ` Oleg Nesterov
2014-07-31 16:19 ` [PATCH v2 tip/core/rcu 0/10] RCU-tasks implementation josh
2014-07-31 16:30 ` Peter Zijlstra
2014-07-31 16:43 ` josh
2014-07-31 16:49 ` Paul E. McKenney
2014-07-31 16:58 ` Paul E. McKenney
2014-07-31 17:20 ` josh
2014-07-31 18:38 ` Paul E. McKenney
2014-07-31 20:58 ` josh
2014-07-31 21:11 ` Paul E. McKenney
2014-07-31 19:29 ` Andi Kleen
2014-07-31 21:08 ` Paul E. McKenney
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