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From: Ingo Molnar <mingo@elte.hu>
To: Andrew Morton <akpm@linux-foundation.org>
Cc: Oleg Nesterov <oleg@tv-sign.ru>,
	ebiederm@xmission.com, paulmck@linux.vnet.ibm.com,
	xemul@openvz.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH] fix tasklist + find_pid() with CONFIG_PREEMPT_RCU
Date: Thu, 31 Jan 2008 14:32:35 +0100	[thread overview]
Message-ID: <20080131133235.GD8499@elte.hu> (raw)
In-Reply-To: <20080129150209.663538cb.akpm@linux-foundation.org>


* Andrew Morton <akpm@linux-foundation.org> wrote:

> On Tue, 29 Jan 2008 19:40:19 +0300
> Oleg Nesterov <oleg@tv-sign.ru> wrote:
> 
> > With CONFIG_PREEMPT_RCU read_lock(tasklist_lock) doesn't imply 
> > rcu_read_lock(),
> 
> I'm suspecting that we have other code which assumes that read_lock, 
> write_lock and spin_lock imply rcu_read_lock().
> 
> I wonder if there are any sane runtime checks we can put in there to 
> find such problems.

we usually caught them via the DEBUG_PREEMPT checks on PREEMPT_RT: stuff 
that has such implicit reliance tends to use smp_processor_id() along 
the way and that gets flagged if the non-preemptability guarantee of 
spin_lock() vanishes.

	Ingo

  parent reply	other threads:[~2008-01-31 13:33 UTC|newest]

Thread overview: 15+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2008-01-29 16:40 Oleg Nesterov
2008-01-29 23:02 ` Andrew Morton
2008-01-30 14:17   ` Peter Zijlstra
2008-01-31 13:32   ` Ingo Molnar [this message]
2008-01-29 23:08 ` Andrew Morton
2008-01-30  2:16   ` Eric W. Biederman
2008-01-30  4:56     ` Paul E. McKenney
2008-01-30  3:24 ` Eric W. Biederman
2008-01-30  5:00   ` Paul E. McKenney
2008-01-30  9:20     ` Eric W. Biederman
2008-01-30  9:48       ` Oleg Nesterov
2008-01-30  9:30   ` Oleg Nesterov
2008-01-30 18:28     ` Eric W. Biederman
2008-01-31  9:31       ` Oleg Nesterov
2009-12-14  2:15 Tetsuo Handa

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