Hello, On Friday 02 September 2011 00:55:54 Luka Perkov wrote: > I also had this issue on my sx763 lantiq based board: > > https://dev.openwrt.org/ticket/9440 > > With symbol table I got this oops: > > Unhandled kernel unaligned access[#1]: > ... bla bla bla (to keep it short) ... > Call Trace: > [<80cb8968>] nf_nat_setup_info+0x2e0/0x6e8 [nf_nat] > [<80d1e158>] masquerade_tg+0xc0/0xe8 [ipt_MASQUERADE] > [<80c646a8>] ipt_do_table+0x3e0/0x484 [ip_tables] > [<80dee0c0>] nf_nat_rule_find+0x28/0x9c [iptable_nat] > [<80dee290>] nf_nat_fn+0x120/0x1a0 [iptable_nat] > [<801baa34>] nf_iterate+0x8c/0xfc > [<801bab34>] nf_hook_slow+0x90/0x17c > [<801c76c8>] ip_output+0xd8/0x104 > [<8019a224>] __netif_receive_skb+0x4d4/0x578 > [<80210128>] br_handle_frame+0x280/0x2b8 > [<80199f9c>] __netif_receive_skb+0x24c/0x578 > [<8019a370>] process_backlog+0xa8/0x188 > [<8019a778>] net_rx_action+0x8c/0x1b8 > [<800215f0>] __do_softirq+0xa8/0x154 > [<800217f0>] do_softirq+0x48/0x68 > [<800031c0>] plat_irq_dispatch+0xf4/0x164 > [<800059ec>] ret_from_irq+0x0/0x4 > [<80005be0>] r4k_wait+0x20/0x40 > [<80007690>] cpu_idle+0x28/0x4c > [<802a58d0>] start_kernel+0x35c/0x378 > > It's easy to reproduce with nmap: > > # nmap -sT -p 1-10000 -T insane -Pn -n some.public.ip.address/24 > > After some time I discovered that the issue is in this lines: > > % sed -n '320,326p' linux-2.6.39.4/net/ipv4/netfilter/nf_nat_core.c > spin_lock_bh(&nf_nat_lock); > /* nf_conntrack_alter_reply might re-allocate exntension aera */ > nat = nfct_nat(ct); > nat->ct = ct; > hlist_add_head_rcu(&nat->bysource, > &net->ipv4.nat_bysource[srchash]); > spin_unlock_bh(&nf_nat_lock); > > Long story short - enable CONFIG_PREEMPT to have functional spin locks: > > http://www.kernel.org/pub/linux/kernel/people/rusty/kernel-locking/x109.htm > l > > Also in linux-2.6.39.4/kernel/Kconfig.preempt you will see for > CONFIG_PREEMPT: > > Select this if you are building a kernel for a desktop or > embedded system with latency requirements in the milliseconds > range > > Because of that I made changes to all kernel config files. > > Signed-off-by: Luka Perkov < openwrt ->-to->- lukaperkov.net >
I am not opposed to enabling CONFIG_PREEMPT on a global basis, but I am afraid this might reveal new locking problems that we have not had so far. At least trunk should be the place where to experiment this. -- Florian _______________________________________________ openwrt-devel mailing list openwrt-devel@lists.openwrt.org https://lists.openwrt.org/mailman/listinfo/openwrt-devel
