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BUG: KCSAN: data-race in enqueue_timer / wbt_wait

write to 0xffff888128c3fd98 of 8 bytes by task 7230 on cpu 1:
 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_schedule_loss_probe net/ipv4/tcp_output.c:2519 [inline]
 tcp_schedule_loss_probe+0x2b7/0x350 net/ipv4/tcp_output.c:2475
 tcp_write_xmit+0xe0e/0x3080 net/ipv4/tcp_output.c:2467
 __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
 call_write_iter include/linux/fs.h:1895 [inline]
 new_sync_write+0x388/0x4a0 fs/read_write.c:483
 __vfs_write+0xb1/0xc0 fs/read_write.c:496

read to 0xffff888128c3fd98 of 8 bytes by task 8638 on cpu 0:
 blk_stat_is_active block/blk-stat.h:131 [inline]
 wbt_wait+0x177/0x250 block/blk-wbt.c:593
 __rq_qos_throttle+0x47/0x70 block/blk-rq-qos.c:72
 rq_qos_throttle block/blk-rq-qos.h:185 [inline]
 blk_mq_make_request+0x29c/0xf60 block/blk-mq.c:1971
 generic_make_request block/blk-core.c:1064 [inline]
 generic_make_request+0x196/0x740 block/blk-core.c:1006
 submit_bio+0x96/0x3c0 block/blk-core.c:1190
 submit_bio_wait+0xb8/0x100 block/bio.c:972
 blkdev_issue_flush+0x163/0x1c0 block/blk-flush.c:459
 ext4_sync_file+0x77c/0xb00 fs/ext4/fsync.c:157
 vfs_fsync_range+0x82/0x150 fs/sync.c:197
 generic_write_sync include/linux/fs.h:2853 [inline]
 ext4_file_write_iter+0x45b/0xa00 fs/ext4/file.c:279
 call_write_iter include/linux/fs.h:1895 [inline]
 do_iter_readv_writev+0x487/0x5b0 fs/read_write.c:693
 do_iter_write fs/read_write.c:970 [inline]
 do_iter_write+0x13b/0x3c0 fs/read_write.c:951
 vfs_iter_write+0x5c/0x80 fs/read_write.c:983

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 PID: 8638 Comm: syz-executor.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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