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BUG: KCSAN: data-race in enqueue_timer / mod_timer

write to 0xffff8881264aa470 of 8 bytes by task 7291 on cpu 0:
 hlist_add_head include/linux/list.h:787 [inline]
 enqueue_timer+0x6c/0x240 kernel/time/timer.c:540
 __mod_timer kernel/time/timer.c:1050 [inline]
 mod_timer+0x4b3/0x7a0 kernel/time/timer.c:1100
 sk_reset_timer+0x2d/0x70 net/core/sock.c:2838
 inet_csk_reset_xmit_timer include/net/inet_connection_sock.h:234 [inline]
 tcp_reset_xmit_timer include/net/tcp.h:1279 [inline]
 tcp_rearm_rto.part.0+0x190/0x240 net/ipv4/tcp_input.c:3009
 tcp_rearm_rto+0x4f/0x60 net/ipv4/tcp_input.c:3012
 tcp_event_new_data_sent+0x1bb/0x1c0 net/ipv4/tcp_output.c:77
 tcp_write_xmit+0xa16/0x3080 net/ipv4/tcp_output.c:2447
 __tcp_push_pending_frames+0x7b/0x1d0 net/ipv4/tcp_output.c:2616
 tcp_push+0x1e9/0x3d0 net/ipv4/tcp.c:724
 tcp_sendmsg_locked+0x1d1e/0x1f30 net/ipv4/tcp.c:1403
 tcp_sendmsg+0x39/0x60 net/ipv4/tcp.c:1434
 inet_sendmsg+0x6d/0x90 net/ipv4/af_inet.c:807
 sock_sendmsg_nosec net/socket.c:637 [inline]
 sock_sendmsg+0x9f/0xc0 net/socket.c:657
 sock_write_iter+0x16b/0x210 net/socket.c:989

read to 0xffff8881264aa470 of 8 bytes by task 7274 on cpu 1:
 __mod_timer kernel/time/timer.c:963 [inline]
 mod_timer+0x59/0x7a0 kernel/time/timer.c:1100
 sk_reset_timer+0x2d/0x70 net/core/sock.c:2838
 inet_csk_reset_xmit_timer include/net/inet_connection_sock.h:234 [inline]
 tcp_reset_xmit_timer include/net/tcp.h:1279 [inline]
 tcp_rearm_rto.part.0+0x190/0x240 net/ipv4/tcp_input.c:3009
 tcp_rearm_rto+0x4f/0x60 net/ipv4/tcp_input.c:3012
 tcp_event_new_data_sent+0x1bb/0x1c0 net/ipv4/tcp_output.c:77
 tcp_write_xmit+0xa16/0x3080 net/ipv4/tcp_output.c:2447
 __tcp_push_pending_frames+0x7b/0x1d0 net/ipv4/tcp_output.c:2616
 tcp_push+0x1e9/0x3d0 net/ipv4/tcp.c:724
 tcp_sendmsg_locked+0x1d1e/0x1f30 net/ipv4/tcp.c:1403
 tcp_sendmsg+0x39/0x60 net/ipv4/tcp.c:1434
 inet_sendmsg+0x6d/0x90 net/ipv4/af_inet.c:807
 sock_sendmsg_nosec net/socket.c:637 [inline]
 sock_sendmsg+0x9f/0xc0 net/socket.c:657
 sock_write_iter+0x16b/0x210 net/socket.c:989

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 PID: 7274 Comm: sshd 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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