On 09/02/14 at 11:38am, Pablo Neira Ayuso wrote:
> The sets are released from the rcu callback, after the rule is removed
> from the chain list, which implies that nfnetlink cannot update the
> hashes (thus, no resizing may occur) and no packets are walking on the
> set anymore.
>
> This resolves a lockdep splat in the nft_hash_destroy() path since the
> nfnl mutex is not held there.
>
> ===============================
> [ INFO: suspicious RCU usage. ]
> 3.16.0-rc2+ #168 Not tainted
> -------------------------------
> net/netfilter/nft_hash.c:362 suspicious rcu_dereference_protected() usage!
>
> other info that might help us debug this:
>
> rcu_scheduler_active = 1, debug_locks = 1
> 1 lock held by ksoftirqd/0/3:
> #0: (rcu_callback){......}, at: [<ffffffff81096393>] rcu_process_callbacks+0x27e/0x4c7
>
> stack backtrace:
> CPU: 0 PID: 3 Comm: ksoftirqd/0 Not tainted 3.16.0-rc2+ #168
> Hardware name: LENOVO 23259H1/23259H1, BIOS G2ET32WW (1.12 ) 05/30/2012
> 0000000000000001 ffff88011769bb98 ffffffff8142c922 0000000000000006
> ffff880117694090 ffff88011769bbc8 ffffffff8107c3ff ffff8800cba52400
> ffff8800c476bea8 ffff8800c476bea8 ffff8800cba52400 ffff88011769bc08
> Call Trace:
> [<ffffffff8142c922>] dump_stack+0x4e/0x68
> [<ffffffff8107c3ff>] lockdep_rcu_suspicious+0xfa/0x103
> [<ffffffffa079931e>] nft_hash_destroy+0x50/0x137 [nft_hash]
> [<ffffffffa078cd57>] nft_set_destroy+0x11/0x2a [nf_tables]
>
> Signed-off-by: Pablo Neira Ayuso <pablo@xxxxxxxxxxxxx>
Acked-by: Thomas Graf <tgraf@xxxxxxx>
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