RHEL7.1: Softirq hang in fib6_run_gc()
Issue
- We see repeated occurrences in the /var/log/messages file of the following at a customer site:
[ 2691.938567] Call Trace:
[ 2691.938572] [<ffffffff815bb278>] fib6_run_gc+0x28/0x100
[ 2691.938575] [<ffffffff815b3ecf>] ip6_dst_gc+0x6f/0xf0
[ 2691.938579] [<ffffffff81503f23>] dst_alloc+0x123/0x170
[ 2691.938582] [<ffffffff814fdcc8>] ? dev_hard_start_xmit+0x328/0x580
[ 2691.938585] [<ffffffff815b4b00>] ip6_rt_copy+0x40/0x340
[ 2691.938587] [<ffffffff815b5a38>] ip6_pol_route.isra.46+0x398/0x480
[ 2691.938589] [<ffffffff815b5b7a>] ip6_pol_route_output+0x2a/0x30
[ 2691.938592] [<ffffffff815dc855>] fib6_rule_action+0xc5/0x200
[ 2691.938594] [<ffffffff815b5b50>] ? ip6_pol_route_input+0x30/0x30
[ 2691.938597] [<ffffffff81517c16>] fib_rules_lookup+0xd6/0x170
[ 2691.938600] [<ffffffff815dcb53>] fib6_rule_lookup+0x53/0xa0
[ 2691.938602] [<ffffffff815b5b50>] ? ip6_pol_route_input+0x30/0x30
[ 2691.938604] [<ffffffff815b3a74>] ip6_route_output+0x74/0xb0
[ 2691.938607] [<ffffffff815a5aa3>] ip6_dst_lookup_tail+0x283/0x2a0
[ 2691.938610] [<ffffffff815a5b23>] ip6_dst_lookup_flow+0x43/0xb0
[ 2691.938613] [<ffffffff815a455b>] inet6_sk_rebuild_header+0x10b/0x180
[ 2691.938616] [<ffffffff815532e9>] ? tcp_transmit_skb+0x479/0x900
[ 2691.938618] [<ffffffff815546ff>] __tcp_retransmit_skb+0x7f/0x5c0
[ 2691.938622] [<ffffffff81080afd>] ? mod_timer+0x11d/0x240
[ 2691.938624] [<ffffffff81554e69>] tcp_retransmit_skb+0x19/0x110
[ 2691.938627] [<ffffffff81556df4>] tcp_retransmit_timer+0x274/0x720
[ 2691.938630] [<ffffffff81557490>] ? tcp_write_timer_handler+0x1f0/0x1f0
[ 2691.938632] [<ffffffff81557340>] tcp_write_timer_handler+0xa0/0x1f0
[ 2691.938634] [<ffffffff815574fc>] tcp_write_timer+0x6c/0x70
[ 2691.938639] [<ffffffff8107df56>] call_timer_fn+0x36/0x110
[ 2691.938641] [<ffffffff81557490>] ? tcp_write_timer_handler+0x1f0/0x1f0
[ 2691.938643] [<ffffffff8107fdcf>] run_timer_softirq+0x21f/0x320
[ 2691.938646] [<ffffffff81077b2f>] __do_softirq+0xef/0x280
[ 2691.938649] [<ffffffff81077cf0>] run_ksoftirqd+0x30/0x50
[ 2691.938652] [<ffffffff8109fc7f>] smpboot_thread_fn+0xff/0x1a0
[ 2691.938654] [<ffffffff816096a9>] ? schedule+0x29/0x70
[ 2691.938656] [<ffffffff8109fb80>] ? lg_global_unlock+0xc0/0xc0
[ 2691.938659] [<ffffffff8109726f>] kthread+0xcf/0xe0
[ 2691.938662] [<ffffffff810971a0>] ? kthread_create_on_node+0x140/0x140
[ 2691.938665] [<ffffffff81614158>] ret_from_fork+0x58/0x90
Environment
- Red Hat Enterprise Linux 7.1
- kernel-3.10.0-229.7.2.el7
- Ipv6
- Following kernel settings related to garbage collection:
net.ipv6.route.gc_elasticity = 8
net.ipv6.route.gc_interval = 30
net.ipv6.route.gc_min_interval = 0
net.ipv6.route.gc_min_interval_ms = 500
net.ipv6.route.gc_thresh = 524288
net.ipv6.route.gc_timeout = 60
net.ipv6.route.max_size = 8388608
net.ipv6.route.min_adv_mss = 1220
net.ipv6.route.mtu_expires = 600
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