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Message-Id: <20090615.023202.245678744.davem@davemloft.net>
Date: Mon, 15 Jun 2009 02:32:02 -0700 (PDT)
From: David Miller <davem@...emloft.net>
To: jarkao2@...il.com
Cc: robert.olsson@....uu.se, zheng.yan@...cle.com,
linux-kernel@...r.kernel.org, netdev@...r.kernel.org
Subject: Re: [PATCH] Re: [BUG] fib_tries related Oops in 2.6.30
From: Jarek Poplawski <jarkao2@...il.com>
Date: Mon, 15 Jun 2009 06:53:33 +0000
> ipv4: Fix fib_trie rebalancing
>
> While doing trie_rebalance(): resize(), inflate(), halve() RCU free
> tnodes before updating their parents. It depends on RCU delaying the
> real destruction, but if RCU readers start after call_rcu() and before
> parent update they could access freed memory.
>
> It is currently prevented with preempt_disable() on the update side,
> but it's not safe, except maybe classic RCU, plus it conflicts with
> memory allocations with GFP_KERNEL flag used from these functions.
>
> This patch explicitly delays freeing of tnodes by adding them to the
> list, which is flushed after the update is finished.
>
> Reported-by: Yan Zheng <zheng.yan@...cle.com>
> Signed-off-by: Jarek Poplawski <jarkao2@...il.com>
Applied to net-next-2.6
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