From mboxrd@z Thu Jan 1 00:00:00 1970 From: Ding Tianhong Subject: [PATCH] ipv6: Fix soft lockup for ipv6 network notifier. Date: Fri, 1 Jul 2016 15:38:44 +0800 Message-ID: <57761E04.8030202@huawei.com> Mime-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 7bit To: , , , Eric Dumazet , "David S. Miller" , Netdev , Cong Wang Return-path: Received: from szxga03-in.huawei.com ([119.145.14.66]:1703 "EHLO szxga03-in.huawei.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752199AbcGAHjB (ORCPT ); Fri, 1 Jul 2016 03:39:01 -0400 Sender: netdev-owner@vger.kernel.org List-ID: The problem was occurs in my system that a lot of drviers register its own handler to the notifiler call chain for netdev_chain, and then create 4095 vlan dev for one nic, and add several ipv6 address on each one of them, just like this: for i in `seq 1 4095`; do ip link add link eth0 name eth0.$i type vlan id $i; done for i in `seq 1 4095`; do ip -6 addr add 2001::$i dev eth0.$i; done for i in `seq 1 4095`; do ip -6 addr add 2002::$i dev eth0.$i; done for i in `seq 1 4095`; do ip -6 addr add 2003::$i dev eth0.$i; done ifconfig eth0 up ifconfig eth0 down then it will halt several seconds, and occurs softlockup: <0>[ 7620.364058]NMI watchdog: BUG: soft lockup - CPU#0 stuck for 23s! [ifconfig:19186] <0>[ 7620.364592]Call trace: <4>[ 7620.364599][] dump_backtrace+0x0/0x220 <4>[ 7620.364603][] show_stack+0x20/0x28 <4>[ 7620.364607][] dump_stack+0x90/0xb0 <4>[ 7620.364612][] watchdog_timer_fn+0x41c/0x460 <4>[ 7620.364617][] __run_hrtimer+0x98/0x2d8 <4>[ 7620.364620][] hrtimer_interrupt+0x110/0x288 <4>[ 7620.364624][] arch_timer_handler_phys+0x38/0x48 <4>[ 7620.364628][] handle_percpu_devid_irq+0x9c/0x190 <4>[ 7620.364632][] generic_handle_irq+0x40/0x58 <4>[ 7620.364635][] __handle_domain_irq+0x68/0xc0 <4>[ 7620.364638][] gic_handle_irq+0xc4/0x1c8 <4>[ 7620.364641]Exception stack(0xffffffc0309b3640 to 0xffffffc0309b3770) <4>[ 7620.364644]3640: 0000000000001000 0000000000000000 ffffffc0309b37c0 ffffffbfa1019cf8 <4>[ 7620.364647]3660: 0000000080000145 ffffffc0309b3958 0000000000000000 ffffffbfa1013008 <4>[ 7620.364651]3680: 00000000000007f0 ffffffbfa131b770 ffffffd08aaadc40 ffffffbfa1019cf8 <4>[ 7620.364654]36a0: ffffffbfa1019cc4 ffffffd089c2b000 ffffffd08eff8000 ffffffc0309b3958 <4>[ 7620.364656]36c0: ffffffbfa101c5c0 0000000000000000 0000000000000000 ffffffbfa101c66c <4>[ 7620.364659]36e0: 7f7f7f7f7f7f7f7f 0000000000000030 ffffffffffffffff ffff000000000000 <4>[ 7620.364662]3700: 0000000000000000 0000000000000000 ffffffc000393d58 0000007f794d67b0 <4>[ 7620.364665]3720: 0000007fe62215d0 ffffffc0309b3830 ffffffc00021d8e0 ffffffbfa1049b68 <4>[ 7620.364668]3740: ffffffc000697578 ffffffc0006974b8 ffffffc0309b3958 0000000000000000 <4>[ 7620.364670]3760: ffffffbfa1013008 00000000000007f0 <4>[ 7620.364673][] el1_irq+0x80/0x100 <4>[ 7620.364692][] fib6_walk+0x3c/0x70 [ipv6] <4>[ 7620.364710][] fib6_clean_tree+0x68/0x90 [ipv6] <4>[ 7620.364727][] __fib6_clean_all+0x88/0xc0 [ipv6] <4>[ 7620.364746][] fib6_clean_all+0x28/0x30 [ipv6] <4>[ 7620.364763][] rt6_ifdown+0x64/0x148 [ipv6] <4>[ 7620.364781][] addrconf_ifdown+0x68/0x540 [ipv6] <4>[ 7620.364798][] addrconf_notify+0xd0/0x8b8 [ipv6] <4>[ 7620.364801][] notifier_call_chain+0x5c/0xa0 <4>[ 7620.364804][] raw_notifier_call_chain+0x20/0x28 <4>[ 7620.364809][] call_netdevice_notifiers_info+0x4c/0x80 <4>[ 7620.364812][] dev_close_many+0xd0/0x138 <4>[ 7620.364821][] vlan_device_event+0x4a8/0x6a0 [8021q] <4>[ 7620.364824][] notifier_call_chain+0x5c/0xa0 <4>[ 7620.364827][] raw_notifier_call_chain+0x20/0x28 <4>[ 7620.364830][] call_netdevice_notifiers_info+0x4c/0x80 <4>[ 7620.364833][] __dev_notify_flags+0xb8/0xe0 <4>[ 7620.364836][] dev_change_flags+0x54/0x68 <4>[ 7620.364840][] devinet_ioctl+0x650/0x700 <4>[ 7620.364843][] inet_ioctl+0xa4/0xc8 <4>[ 7620.364847][] sock_do_ioctl+0x44/0x88 <4>[ 7620.364850][] sock_ioctl+0x23c/0x308 <4>[ 7620.364854][] do_vfs_ioctl+0x48c/0x620 <4>[ 7620.364857][] SyS_ioctl+0x94/0xa8 =================================cut here======================================== It looks that the notifier_call_chain has to deal with too much handler, and will not feed the watchdog until finish the work, and the notifier_call_chain would call the ipv6_dev_notf several times and hold the cpu for a long time, so add cond_resched() in the ipv6_dev_notf in order to schedule out in the network notifiers to avoid softlocking to fix this problem. Suggested-by: Eric Dumazet Signed-off-by: Ding Tianhong --- net/ipv6/addrconf.c | 6 ++++++ 1 file changed, 6 insertions(+) diff --git a/net/ipv6/addrconf.c b/net/ipv6/addrconf.c index f555f4f..e294a3d 100644 --- a/net/ipv6/addrconf.c +++ b/net/ipv6/addrconf.c @@ -3284,6 +3284,12 @@ restart: spin_unlock_bh(&addrconf_hash_lock); } + /* + * It is safe here to schedule out to avoid softlocking if preempt + * is disabled. + */ + cond_resched(); + write_lock_bh(&idev->lock); addrconf_del_rs_timer(idev); -- 1.9.0