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BUG: KCSAN: data-race in mod_timer / timer_clear_idle

write to 0xffff88812c11dca4 of 1 bytes by task 0 on cpu 1:
 timer_clear_idle+0x3d/0x50 kernel/time/timer.c:1676
 tick_nohz_restart_sched_tick kernel/time/tick-sched.c:860 [inline]
 __tick_nohz_idle_restart_tick+0x32/0x1a0 kernel/time/tick-sched.c:1161
 tick_nohz_idle_exit+0x19c/0x1d0 kernel/time/tick-sched.c:1202
 do_idle+0xac/0x290 kernel/sched/idle.c:282
 cpu_startup_entry+0x14/0x20 kernel/sched/idle.c:361
 start_secondary+0x169/0x1b0 arch/x86/kernel/smpboot.c:268
 secondary_startup_64+0xa4/0xb0 arch/x86/kernel/head_64.S:242

read to 0xffff88812c11dca4 of 1 bytes by task 8919 on cpu 0:
 forward_timer_base kernel/time/timer.c:892 [inline]
 __mod_timer kernel/time/timer.c:1010 [inline]
 mod_timer+0x546/0x830 kernel/time/timer.c:1101
 sk_reset_timer+0x29/0xc0 net/core/sock.c:2863
 inet_csk_reset_xmit_timer include/net/inet_connection_sock.h:234 [inline]
 tcp_reset_xmit_timer include/net/tcp.h:1310 [inline]
 tcp_rearm_rto net/ipv4/tcp_input.c:3016 [inline]
 tcp_rearm_rto+0x1ce/0x280 net/ipv4/tcp_input.c:2992
 tcp_event_new_data_sent+0x23f/0x260 net/ipv4/tcp_output.c:81
 tcp_write_xmit+0x5c6/0x31e0 net/ipv4/tcp_output.c:2524
 __tcp_push_pending_frames+0x72/0x1b0 net/ipv4/tcp_output.c:2693
 tcp_push+0x1ec/0x3e0 net/ipv4/tcp.c:725
 tcp_sendmsg_locked+0x1de3/0x20f0 net/ipv4/tcp.c:1403
 tcp_sendmsg+0x35/0x50 net/ipv4/tcp.c:1433
 inet_sendmsg+0x69/0x90 net/ipv4/af_inet.c:807
 sock_sendmsg_nosec net/socket.c:652 [inline]
 sock_sendmsg+0x98/0xc0 net/socket.c:672
 sock_write_iter+0x186/0x240 net/socket.c:1004
 call_write_iter include/linux/fs.h:1907 [inline]
 new_sync_write+0x303/0x400 fs/read_write.c:484
 __vfs_write+0x9e/0xb0 fs/read_write.c:497
 vfs_write fs/read_write.c:559 [inline]
 vfs_write+0x189/0x380 fs/read_write.c:543
 ksys_write+0x16a/0x1a0 fs/read_write.c:612
 __do_sys_write fs/read_write.c:624 [inline]
 __se_sys_write fs/read_write.c:621 [inline]
 __x64_sys_write+0x49/0x60 fs/read_write.c:621
 do_syscall_64+0xc7/0x3b0 arch/x86/entry/common.c:295
 entry_SYSCALL_64_after_hwframe+0x44/0xa9

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 PID: 8919 Comm: syz-fuzzer Not tainted 5.7.0-rc1-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
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