From: Peter Zijlstra <peterz@infradead.org>
To: Oleg Nesterov <oleg@redhat.com>
Cc: "Ni, BaoleX" <baolex.ni@intel.com>,
"mingo@redhat.com" <mingo@redhat.com>,
"acme@kernel.org" <acme@kernel.org>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
"alexander.shishkin@linux.intel.com"
<alexander.shishkin@linux.intel.com>,
"Liu, Chuansheng" <chuansheng.liu@intel.com>
Subject: Re: hit a KASan bug related to Perf during stress test
Date: Wed, 26 Oct 2016 11:03:32 +0200 [thread overview]
Message-ID: <20161026090332.GA3102@twins.programming.kicks-ass.net> (raw)
In-Reply-To: <20161025144126.GD4326@redhat.com>
On Tue, Oct 25, 2016 at 04:41:26PM +0200, Oleg Nesterov wrote:
> >
> > So what serialization would close that race? __task_pid_nr_ns() only
> > seems to use RCU nothing more.
>
> I do not see how can we close this race, we obviously do not want to use
> any locking.
>
> That is why I tried to suggest
>
> nr = __task_pid_nr_ns(p, type, event->ns);
> if (!nr && !is_idle_task(p))
> nr = -1;
> return nr;
>
> but this will report -1 if p runs in another namespace, so perhaps we
> can do
>
> nr = __task_pid_nr_ns(p, type, event->ns);
> if (!nr && p->exit_state)
> // it has already called exit_notify
> nr = -1;
> return nr;
I think I'm asking how __task_pid_nr_ns() isn't susceptible to this race
;-)
next prev parent reply other threads:[~2016-10-26 9:03 UTC|newest]
Thread overview: 27+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <318B87A793BE164187D8851D6CE09D64371C8811@shsmsx102.ccr.corp.intel.com>
2016-10-24 9:53 ` hit a KASan bug related to Perf during stress test Peter Zijlstra
2016-10-24 11:15 ` Oleg Nesterov
2016-10-24 11:24 ` Peter Zijlstra
2016-10-24 12:02 ` Oleg Nesterov
2016-10-24 12:10 ` Oleg Nesterov
2016-10-24 12:22 ` Peter Zijlstra
2016-10-24 12:29 ` Oleg Nesterov
2016-10-24 12:38 ` Peter Zijlstra
2016-10-24 13:25 ` Oleg Nesterov
2016-10-24 13:40 ` Oleg Nesterov
2016-10-24 14:17 ` Peter Zijlstra
2016-10-24 14:36 ` Peter Zijlstra
2016-10-24 15:39 ` Oleg Nesterov
2016-10-24 15:53 ` Oleg Nesterov
2016-10-25 6:55 ` Ni, BaoleX
2016-10-25 9:28 ` Peter Zijlstra
2016-10-25 14:41 ` Oleg Nesterov
2016-10-26 9:03 ` Peter Zijlstra [this message]
2016-10-26 16:10 ` Oleg Nesterov
2016-10-24 12:19 ` Peter Zijlstra
2016-10-24 11:27 ` Peter Zijlstra
2016-10-24 11:29 ` Peter Zijlstra
2016-10-24 12:04 ` Jiri Olsa
2016-10-24 12:12 ` Peter Zijlstra
2016-10-24 12:11 ` Peter Zijlstra
2016-10-24 12:21 ` Oleg Nesterov
2016-10-24 12:27 ` Peter Zijlstra
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