Pablo Neira Ayuso <pablo@xxxxxxxxxxxxx> wrote: > On Wed, Dec 09, 2015 at 06:30:09PM +0100, Florian Westphal wrote: > > Ulrich reports soft lockup with following (shortened) callchain: > > > > NMI watchdog: BUG: soft lockup - CPU#1 stuck for 22s! > > __netif_receive_skb_core+0x6e4/0x774 > > process_backlog+0x94/0x160 > > net_rx_action+0x88/0x178 > > call_do_softirq+0x24/0x3c > > do_softirq+0x54/0x6c > > __local_bh_enable_ip+0x7c/0xbc > > nf_ct_iterate_cleanup+0x11c/0x22c [nf_conntrack] > > masq_inet_event+0x20/0x30 [nf_nat_masquerade_ipv6] > > atomic_notifier_call_chain+0x1c/0x2c > > ipv6_del_addr+0x1bc/0x220 [ipv6] > > > > Problem is that nf_ct_iterate_cleanup can run for a very long time > > since it can be interrupted by softirq processing. > > Moreover, atomic_notifier_call_chain runs with rcu readlock held. > > > > So lets call cond_resched() in nf_ct_iterate_cleanup loop and defer > > the call to a work queue for the atomic_notifier_call_chain case. > > Don't we potentially have the same problem in IPv4? No, the inet notifier appears to be fine (blocking notifier). The only nf_ct_iterate_cleanup callsite that I found to be problematic (i.e., not preemptible) is the ipv6 address deletion notifier in ipv6 masquarading. I also tried with nf-next + CONFIG_DEBUG_ATOMIC_SLEEP + this patch and I saw no error on ipv4 address deletion w. ip4 masquerade module loaded. -- To unsubscribe from this list: send the line "unsubscribe netfilter-devel" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
