From: Oleg Nesterov <oleg@redhat.com>
To: Peter Zijlstra <peterz@infradead.org>
Cc: Kirill Tkhai <ktkhai@parallels.com>,
linux-kernel@vger.kernel.org, Ingo Molnar <mingo@redhat.com>,
Vladimir Davydov <vdavydov@parallels.com>,
Kirill Tkhai <tkhai@yandex.ru>
Subject: Re: [PATCH RFC] sched: Revert delayed_put_task_struct() and fix use after free
Date: Fri, 17 Oct 2014 00:05:40 +0200 [thread overview]
Message-ID: <20141016220540.GA29796@redhat.com> (raw)
In-Reply-To: <20141016080106.GD7369@worktop.fdxtended.com>
On 10/16, Peter Zijlstra wrote:
>
> On Wed, Oct 15, 2014 at 05:06:41PM +0200, Oleg Nesterov wrote:
> >
> > At least the code like
> >
> > rcu_read_lock();
> > get_task_struct(foreign_rq->curr);
> > rcu_read_unlock();
> >
> > is certainly wrong. And _probably_ the problem should be fixed here. Perhaps
> > we can add try_to_get_task_struct() which does atomic_inc_not_zero() ...
>
> There is an rcu_read_lock() around it through task_numa_compare().
Yes, and the code above has rcu_read_lock() too. But it doesn't help
as Kirill pointed out.
Sorry, didn't have time today to read other emails in this thread,
will do tomorrow and (probably) send the patch which adds PF_EXITING
check.
Oleg.
next prev parent reply other threads:[~2014-10-16 22:09 UTC|newest]
Thread overview: 32+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-10-15 12:31 [PATCH RFC] sched: Revert delayed_put_task_struct() and fix use after free Kirill Tkhai
2014-10-15 15:06 ` Oleg Nesterov
2014-10-15 19:40 ` Oleg Nesterov
2014-10-15 21:46 ` Kirill Tkhai
2014-10-15 22:02 ` Kirill Tkhai
2014-10-16 7:59 ` Peter Zijlstra
2014-10-16 8:16 ` Kirill Tkhai
2014-10-16 9:43 ` Peter Zijlstra
2014-10-16 9:50 ` Kirill Tkhai
2014-10-16 9:51 ` Kirill Tkhai
2014-10-16 10:04 ` Kirill Tkhai
2014-10-17 21:34 ` Oleg Nesterov
2014-10-16 7:56 ` Peter Zijlstra
2014-10-16 8:01 ` Peter Zijlstra
2014-10-16 22:05 ` Oleg Nesterov [this message]
2014-10-17 21:36 ` [PATCH] sched/numa: fix unsafe get_task_struct() in task_numa_assign() Oleg Nesterov
2014-10-18 8:15 ` Kirill Tkhai
2014-10-18 8:33 ` Kirill Tkhai
2014-10-18 19:36 ` Peter Zijlstra
2014-10-18 21:18 ` Oleg Nesterov
2014-10-19 8:20 ` Kirill Tkhai
2014-10-18 20:56 ` Oleg Nesterov
2014-10-18 23:13 ` Kirill Tkhai
2014-10-19 19:24 ` Oleg Nesterov
2014-10-19 19:37 ` Oleg Nesterov
2014-10-19 19:43 ` Oleg Nesterov
2014-10-20 9:03 ` Kirill Tkhai
2014-10-20 9:13 ` Peter Zijlstra
2014-10-20 10:36 ` Kirill Tkhai
2014-10-20 9:00 ` Kirill Tkhai
2014-10-19 21:38 ` Peter Zijlstra
2014-10-20 8:56 ` Kirill Tkhai
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