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BUG: KCSAN: data-race in fib6_ifup / find_match

write to 0xffff8880ab31a3af of 1 bytes by task 12850 on cpu 0:
 fib6_ifup+0xd7/0x100 net/ipv6/route.c:4588
 fib6_clean_node+0x194/0x310 net/ipv6/ip6_fib.c:2077
 fib6_walk_continue+0x2e3/0x440 net/ipv6/ip6_fib.c:2002
 fib6_walk+0x10d/0x160 net/ipv6/ip6_fib.c:2050
 fib6_clean_tree+0xef/0x120 net/ipv6/ip6_fib.c:2130
 __fib6_clean_all+0xbd/0x150 net/ipv6/ip6_fib.c:2146
 fib6_clean_all+0x34/0x50 net/ipv6/ip6_fib.c:2157
 rt6_sync_up+0x9f/0x110 net/ipv6/route.c:4608
 addrconf_notify+0x254/0x1480 net/ipv6/addrconf.c:3604
 notifier_call_chain+0xd7/0x160 kernel/notifier.c:95
 __raw_notifier_call_chain kernel/notifier.c:396 [inline]
 raw_notifier_call_chain+0x37/0x50 kernel/notifier.c:403
 call_netdevice_notifiers_info+0x48/0xc0 net/core/dev.c:1749
 netdev_state_change net/core/dev.c:1352 [inline]
 netdev_state_change+0xb2/0xd0 net/core/dev.c:1345
 linkwatch_do_dev+0xd8/0xf0 net/core/link_watch.c:159

read to 0xffff8880ab31a3af of 1 bytes by interrupt on cpu 1:
 find_match+0x52/0x790 net/ipv6/route.c:740
 __find_rr_leaf+0xe3/0x780 net/ipv6/route.c:831
 find_rr_leaf net/ipv6/route.c:852 [inline]
 rt6_select net/ipv6/route.c:896 [inline]
 fib6_table_lookup+0x383/0x650 net/ipv6/route.c:2164
 ip6_pol_route+0xee/0x5c0 net/ipv6/route.c:2200
 ip6_pol_route_input+0x4d/0x70 net/ipv6/route.c:2258
 fib6_rule_lookup+0x95/0x470 net/ipv6/fib6_rules.c:113
 ip6_route_input_lookup+0x9f/0xc0 net/ipv6/route.c:2270
 ip6_route_input+0x41e/0x4b0 net/ipv6/route.c:2442
 ip6_rcv_finish_core.isra.0+0x97/0x1f0 net/ipv6/ip6_input.c:63
 ip6_rcv_finish+0xee/0x140 net/ipv6/ip6_input.c:74
 NF_HOOK include/linux/netfilter.h:305 [inline]
 NF_HOOK include/linux/netfilter.h:299 [inline]
 ipv6_rcv+0x1a1/0x1b0 net/ipv6/ip6_input.c:284
 __netif_receive_skb_one_core+0xa7/0xe0 net/core/dev.c:5010
 __netif_receive_skb+0x37/0xf0 net/core/dev.c:5124

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 PID: 16 Comm: ksoftirqd/1 Not tainted 5.4.0-rc3+ #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
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