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BUG: KCSAN: data-race in __nf_conntrack_alloc / gc_worker

write to 0xffff8881221c8108 of 4 bytes by task 25 on cpu 1:
 __nf_conntrack_alloc+0x147/0x270 net/netfilter/nf_conntrack_core.c:1508
 init_conntrack+0x1c8/0xab0 net/netfilter/nf_conntrack_core.c:1576
 resolve_normal_ct net/netfilter/nf_conntrack_core.c:1674 [inline]
 nf_conntrack_in+0x3af/0xb0e net/netfilter/nf_conntrack_core.c:1834
 ipv4_conntrack_local+0xc2/0x120 net/netfilter/nf_conntrack_proto.c:200
 nf_hook_entry_hookfn include/linux/netfilter.h:136 [inline]
 nf_hook_slow+0x72/0x170 net/netfilter/core.c:512
 nf_hook include/linux/netfilter.h:256 [inline]
 __ip_local_out+0x282/0x2a0 net/ipv4/ip_output.c:114
 ip_local_out net/ipv4/ip_output.c:123 [inline]
 __ip_queue_xmit+0x976/0x9e0 net/ipv4/ip_output.c:530
 ip_queue_xmit+0x34/0x40 net/ipv4/ip_output.c:544
 __tcp_transmit_skb+0x1320/0x1810 net/ipv4/tcp_output.c:1246
 tcp_transmit_skb net/ipv4/tcp_output.c:1264 [inline]
 tcp_connect+0x5ac/0x1090 net/ipv4/tcp_output.c:3686
 tcp_v4_connect+0xab0/0xb80 net/ipv4/tcp_ipv4.c:312
 __inet_stream_connect+0x5c6/0x6b0 net/ipv4/af_inet.c:661
 inet_stream_connect+0x44/0x70 net/ipv4/af_inet.c:725
 rds_tcp_conn_path_connect+0x366/0x430 net/rds/tcp_connect.c:172
 rds_connect_worker+0x125/0x1a0 net/rds/threads.c:176
 process_one_work+0x3e1/0x9a0 kernel/workqueue.c:2269
 worker_thread+0x665/0xbe0 kernel/workqueue.c:2415
 kthread+0x20d/0x230 kernel/kthread.c:292
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:294

read to 0xffff8881221c8108 of 4 bytes by task 31722 on cpu 0:
 gc_worker+0x230/0x840 arch/x86/include/asm/bitops.h:207
 process_one_work+0x3e1/0x9a0 kernel/workqueue.c:2269
 worker_thread+0x665/0xbe0 kernel/workqueue.c:2415
 kthread+0x20d/0x230 kernel/kthread.c:292
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:294

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 PID: 31722 Comm: kworker/0:47 Not tainted 5.9.0-rc4-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Workqueue: events_power_efficient gc_worker
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