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BUG: KCSAN: data-race in enqueue_timer / wbt_wait

write to 0xffff88812900ed18 of 8 bytes by task 1235 on cpu 0:
 hlist_add_head include/linux/list.h:787 [inline]
 enqueue_timer+0x6c/0x210 kernel/time/timer.c:540
 __internal_add_timer+0x4f/0x60 kernel/time/timer.c:553
 internal_add_timer kernel/time/timer.c:595 [inline]
 __mod_timer kernel/time/timer.c:1053 [inline]
 mod_timer kernel/time/timer.c:1100 [inline]
 add_timer+0x250/0x550 kernel/time/timer.c:1136
 __queue_delayed_work+0x13b/0x1d0 kernel/workqueue.c:1644
 queue_delayed_work_on+0xf3/0x110 kernel/workqueue.c:1669
 queue_delayed_work include/linux/workqueue.h:509 [inline]
 schedule_delayed_work include/linux/workqueue.h:610 [inline]
 nsim_dev_trap_report_work+0x581/0x5a0 drivers/net/netdevsim/dev.c:416
 process_one_work+0x3d4/0x890 kernel/workqueue.c:2264
 worker_thread+0xa0/0x800 kernel/workqueue.c:2410
 kthread+0x1d4/0x200 drivers/block/aoe/aoecmd.c:1253
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:352

read to 0xffff88812900ed18 of 8 bytes by task 8040 on cpu 1:
 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:182 [inline]
 blk_mq_make_request+0x29c/0xf60 block/blk-mq.c:1932
 generic_make_request block/blk-core.c:1066 [inline]
 generic_make_request+0x196/0x700 block/blk-core.c:1008
 submit_bio+0x96/0x3c0 block/blk-core.c:1192
 submit_bh_wbc+0x40f/0x460 fs/buffer.c:3135
 submit_bh fs/buffer.c:3141 [inline]
 __sync_dirty_buffer+0xd3/0x210 fs/buffer.c:3227
 sync_dirty_buffer+0x24/0x40 fs/buffer.c:3240
 __ext4_handle_dirty_metadata+0x19c/0x3e0 fs/ext4/ext4_jbd2.c:316
 ext4_handle_dirty_dirblock+0x20a/0x280 fs/ext4/namei.c:404
 ext4_delete_entry+0x266/0x2c0 fs/ext4/namei.c:2509
 ext4_rmdir fs/ext4/namei.c:3115 [inline]
 ext4_rmdir+0x3ca/0x700 fs/ext4/namei.c:3067
 vfs_rmdir fs/namei.c:3882 [inline]
 vfs_rmdir+0x119/0x300 fs/namei.c:3861
 do_rmdir+0x2cb/0x300 fs/namei.c:3944
 __do_sys_rmdir fs/namei.c:3962 [inline]
 __se_sys_rmdir fs/namei.c:3960 [inline]
 __x64_sys_rmdir+0x2f/0x40 fs/namei.c:3960
 do_syscall_64+0xcc/0x3a0 arch/x86/entry/common.c:294
 entry_SYSCALL_64_after_hwframe+0x44/0xa9

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 PID: 8040 Comm: syz-executor.3 Not tainted 5.5.0-rc1-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
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