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BUG: KCSAN: data-race in wbt_done / wbt_issue

write to 0xffff88821a998f28 of 8 bytes by interrupt on cpu 0:
 wbt_done+0x16e/0x1b0 block/blk-wbt.c:191
 __rq_qos_done+0x4a/0x80 block/blk-rq-qos.c:45
 rq_qos_done block/blk-rq-qos.h:156 [inline]
 blk_mq_free_request+0x24c/0x320 block/blk-mq.c:532
 __blk_mq_end_request block/blk-mq.c:561 [inline]
 blk_mq_end_request+0x28f/0x2b0 block/blk-mq.c:570
 lo_complete_rq+0x136/0x1a0 drivers/block/loop.c:485
 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

read to 0xffff88821a998f28 of 8 bytes by task 2493 on cpu 1:
 wbt_issue block/blk-wbt.c:617 [inline]
 wbt_issue+0x8e/0xf0 block/blk-wbt.c:603
 __rq_qos_issue+0x4a/0x80 block/blk-rq-qos.c:54
 rq_qos_issue block/blk-rq-qos.h:162 [inline]
 blk_mq_start_request+0x32a/0x370 block/blk-mq.c:688
 loop_queue_rq+0x64/0x2b0 drivers/block/loop.c:1898
 blk_mq_dispatch_rq_list+0xbe9/0xe40 block/blk-mq.c:1273
 blk_mq_do_dispatch_sched+0x11d/0x260 block/blk-mq-sched.c:115
 blk_mq_sched_dispatch_requests+0x2b4/0x380 block/blk-mq-sched.c:211
 __blk_mq_run_hw_queue+0xb7/0x160 block/blk-mq.c:1403
 blk_mq_run_work_fn+0x57/0x70 block/blk-mq.c:1636
 process_one_work+0x3d4/0x890 kernel/workqueue.c:2269
 worker_thread+0xa0/0x800 kernel/workqueue.c:2415
 kthread+0x1d4/0x200 drivers/block/aoe/aoecmd.c:1253
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:352

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 PID: 2493 Comm: kworker/1:1H Not tainted 5.4.0-rc3+ #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Workqueue: kblockd blk_mq_run_work_fn
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