linux-kernel - Re: mmotm 2010-04-05-16-09 uploaded

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Message-ID: <4BBDF7E7.708@trash.net>
Date:	Thu, 08 Apr 2010 17:36:07 +0200
From:	Patrick McHardy <kaber@...sh.net>
To:	Valdis.Kletnieks@...edu
CC:	Andrew Morton <akpm@...ux-foundation.org>,
	Peter Zijlstra <peterz@...radead.org>,
	Ingo Molnar <mingo@...hat.com>,
	"David S. Miller" <davem@...emloft.net>,
	linux-kernel@...r.kernel.org, netfilter-devel@...r.kernel.org,
	netdev@...r.kernel.org
Subject: Re: mmotm 2010-04-05-16-09 uploaded

Valdis.Kletnieks@...edu wrote:
> On Thu, 08 Apr 2010 13:41:00 +0200, Patrick McHardy said:
>>> [   11.488579] ===================================================
>>> [   11.489529] [ INFO: suspicious rcu_dereference_check() usage. ]
>>> [   11.489988] ---------------------------------------------------
>>> [   11.490494] net/netfilter/nf_conntrack_ecache.c:88 invoked rcu_dereference_check() without protection!
>>> [   11.491024] 
>> There are some unnecessary rcu_dereference() calls in the conntrack
>> notifier registration and unregistration functions.
>>
>> Does this fix it?
> 
> Well, it *changed* it.  Does the rcu_defererence_check() only fire on the
> first time it hits something, so we've fixed the first one and now we get to
> see the second one?

It appears that way, otherwise you should have seen a second warning in
nf_conntrack_ecache the last time.

> (For what it's worth, if this is going to be one-at-a-time whack-a-mole, I'm
> OK on that, just want to know up front.)

I went through the other files and I believe this should be it.
We already removed most of these incorrect rcu_dereference()
calls a while back.

> [    9.299425] ip_tables: (C) 2000-2006 Netfilter Core Team
> [    9.299486] 
> [    9.299486] ===================================================
> [    9.300499] [ INFO: suspicious rcu_dereference_check() usage. ]
> [    9.301001] ---------------------------------------------------
> [    9.301523] net/netfilter/nf_log.c:55 invoked rcu_dereference_check() without protection!
> [    9.302066] 


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