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BUG: KCSAN: data-race in blk_stat_add / enqueue_timer

read to 0xffff88821a906c18 of 8 bytes by interrupt on cpu 1:
 blk_stat_is_active block/blk-stat.h:131 [inline]
 blk_stat_add+0xc9/0x290 block/blk-stat.c:65
 __blk_mq_end_request block/blk-mq.c:549 [inline]
 blk_mq_end_request+0x256/0x2b0 block/blk-mq.c:570
 end_cmd drivers/block/null_blk_main.c:622 [inline]
 end_cmd+0xa9/0x1a0 drivers/block/null_blk_main.c:616
 null_complete_rq+0x22/0x30 drivers/block/null_blk_main.c:649
 blk_done_softirq+0x1eb/0x250 block/blk-softirq.c:37
 __do_softirq+0x115/0x33f kernel/softirq.c:292
 run_ksoftirqd+0x46/0x60 kernel/softirq.c:603
 smpboot_thread_fn+0x37d/0x4a0 kernel/smpboot.c:165
 kthread+0x1d4/0x200 drivers/block/aoe/aoecmd.c:1253
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:352

write to 0xffff88821a906c18 of 8 bytes by task 7652 on cpu 0:
 hlist_add_head include/linux/list.h:787 [inline]
 enqueue_timer+0x6c/0x210 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:2842
 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+0x2ef/0x390 net/ipv4/tcp_output.c:2475
 tcp_write_xmit+0xe6f/0x3120 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:726
 tcp_sendmsg_locked+0x1d2b/0x1fb0 net/ipv4/tcp.c:1405
 tcp_sendmsg+0x39/0x60 net/ipv4/tcp.c:1436
 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
 vfs_write fs/read_write.c:558 [inline]
 vfs_write+0x18a/0x390 fs/read_write.c:542
 ksys_write+0xd5/0x1b0 fs/read_write.c:611
 __do_sys_write fs/read_write.c:623 [inline]
 __se_sys_write fs/read_write.c:620 [inline]
 __x64_sys_write+0x4c/0x60 fs/read_write.c:620
 do_syscall_64+0xcc/0x370 arch/x86/entry/common.c:290
 entry_SYSCALL_64_after_hwframe+0x44/0xa9

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 PID: 7652 Comm: syz-fuzzer Not tainted 5.4.0-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
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