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BUG: KCSAN: data-race in br_fdb_update / br_fdb_update

read to 0xffff888139acfcc0 of 8 bytes by interrupt on cpu 0:
 br_fdb_update+0x10d/0x540 net/bridge/br_fdb.c:723
 br_handle_frame_finish+0x1f0/0xbe0 net/bridge/br_input.c:96
 br_nf_hook_thresh+0x194/0x1d0
 br_nf_pre_routing_finish_ipv6+0x4dc/0x500
 NF_HOOK include/linux/netfilter.h:307 [inline]
 br_nf_pre_routing_ipv6+0x1ea/0x280 net/bridge/br_netfilter_ipv6.c:236
 br_nf_pre_routing+0x4d1/0xb30 net/bridge/br_netfilter_hooks.c:505
 nf_hook_entry_hookfn include/linux/netfilter.h:142 [inline]
 nf_hook_bridge_pre net/bridge/br_input.c:230 [inline]
 br_handle_frame+0x463/0xba0 net/bridge/br_input.c:370
 __netif_receive_skb_core+0xa4b/0x1df0 net/core/dev.c:5356
 __netif_receive_skb_one_core net/core/dev.c:5460 [inline]
 __netif_receive_skb+0x52/0x1b0 net/core/dev.c:5576
 process_backlog+0x23f/0x3e0 net/core/dev.c:6452
 __napi_poll+0x65/0x3f0 net/core/dev.c:7020
 napi_poll net/core/dev.c:7087 [inline]
 net_rx_action+0x29e/0x650 net/core/dev.c:7174
 __do_softirq+0x158/0x2de kernel/softirq.c:558
 run_ksoftirqd+0x1f/0x30 kernel/softirq.c:920
 smpboot_thread_fn+0x308/0x4a0 kernel/smpboot.c:164
 kthread+0x2c7/0x2e0 kernel/kthread.c:327
 ret_from_fork+0x1f/0x30

write to 0xffff888139acfcc0 of 8 bytes by interrupt on cpu 1:
 br_fdb_update+0x14b/0x540 net/bridge/br_fdb.c:724
 br_handle_frame_finish+0x1f0/0xbe0 net/bridge/br_input.c:96
 br_nf_hook_thresh+0x194/0x1d0
 br_nf_pre_routing_finish_ipv6+0x4dc/0x500
 NF_HOOK include/linux/netfilter.h:307 [inline]
 br_nf_pre_routing_ipv6+0x1ea/0x280 net/bridge/br_netfilter_ipv6.c:236
 br_nf_pre_routing+0x4d1/0xb30 net/bridge/br_netfilter_hooks.c:505
 nf_hook_entry_hookfn include/linux/netfilter.h:142 [inline]
 nf_hook_bridge_pre net/bridge/br_input.c:230 [inline]
 br_handle_frame+0x463/0xba0 net/bridge/br_input.c:370
 __netif_receive_skb_core+0xa4b/0x1df0 net/core/dev.c:5356
 __netif_receive_skb_one_core net/core/dev.c:5460 [inline]
 __netif_receive_skb+0x52/0x1b0 net/core/dev.c:5576
 process_backlog+0x23f/0x3e0 net/core/dev.c:6452
 __napi_poll+0x65/0x3f0 net/core/dev.c:7020
 napi_poll net/core/dev.c:7087 [inline]
 net_rx_action+0x29e/0x650 net/core/dev.c:7174
 __do_softirq+0x158/0x2de kernel/softirq.c:558
 do_softirq+0xb1/0xf0 kernel/softirq.c:459
 __local_bh_enable_ip+0x68/0x70 kernel/softirq.c:383
 __raw_read_unlock_bh include/linux/rwlock_api_smp.h:249 [inline]
 _raw_read_unlock_bh+0x17/0x20 kernel/locking/spinlock.c:284
 rds_tcp_data_ready+0x287/0x2c0 net/rds/tcp_recv.c:332
 tcp_data_ready+0x19e/0x280 net/ipv4/tcp_input.c:4977
 tcp_data_queue+0x1533/0x3010 net/ipv4/tcp_input.c:5047
 tcp_rcv_established+0x878/0x10e0 net/ipv4/tcp_input.c:5945
 tcp_v6_do_rcv+0x36e/0xa50 net/ipv6/tcp_ipv6.c:1521
 sk_backlog_rcv include/net/sock.h:1030 [inline]
 __release_sock+0xf2/0x270 net/core/sock.c:2768
 release_sock+0x40/0x110 net/core/sock.c:3300
 tcp_sock_set_cork+0xf4/0x100 net/ipv4/tcp.c:3195
 rds_tcp_xmit_path_complete+0x37/0x40 net/rds/tcp_send.c:52
 rds_send_xmit+0x1032/0x1500 net/rds/send.c:422
 rds_send_worker+0x43/0x200 net/rds/threads.c:200
 process_one_work+0x3fc/0x980 kernel/workqueue.c:2298
 worker_thread+0x616/0xa70 kernel/workqueue.c:2445
 kthread+0x2c7/0x2e0 kernel/kthread.c:327
 ret_from_fork+0x1f/0x30

value changed: 0x000000010001f4fe -> 0x000000010001f4ff

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 PID: 5267 Comm: kworker/u4:8 Tainted: G        W         5.15.0-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Workqueue: krdsd rds_send_worker
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