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BUG: KCSAN: data-race in __blk_mq_sched_dispatch_requests / __blk_mq_sched_dispatch_requests

write to 0xffff888102548810 of 8 bytes by task 3248 on cpu 0:
 INIT_LIST_HEAD include/linux/list.h:36 [inline]
 list_splice_init include/linux/list.h:483 [inline]
 __blk_mq_sched_dispatch_requests+0x16a/0x2a0 block/blk-mq-sched.c:289
 blk_mq_sched_dispatch_requests+0x8f/0xf0 block/blk-mq-sched.c:341
 __blk_mq_run_hw_queue+0xee/0x1c0 block/blk-mq.c:1532
 __blk_mq_delay_run_hw_queue+0x18e/0x340 block/blk-mq.c:1609
 blk_mq_run_hw_queue+0x231/0x260 block/blk-mq.c:1662
 blk_mq_run_hw_queues block/blk-mq.c:1680 [inline]
 blk_mq_requeue_work+0x423/0x490 block/blk-mq.c:816
 process_one_work+0x3e1/0x950 kernel/workqueue.c:2272
 worker_thread+0x635/0xb90 kernel/workqueue.c:2418
 kthread+0x1ff/0x220 kernel/kthread.c:292
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:296

read to 0xffff888102548810 of 8 bytes by task 3249 on cpu 1:
 list_empty_careful include/linux/list.h:319 [inline]
 __blk_mq_sched_dispatch_requests+0xb1/0x2a0 block/blk-mq-sched.c:286
 blk_mq_sched_dispatch_requests+0x8f/0xf0 block/blk-mq-sched.c:341
 __blk_mq_run_hw_queue+0xee/0x1c0 block/blk-mq.c:1532
 blk_mq_run_work_fn+0x3d/0x50 block/blk-mq.c:1810
 process_one_work+0x3e1/0x950 kernel/workqueue.c:2272
 worker_thread+0x635/0xb90 kernel/workqueue.c:2418
 kthread+0x1ff/0x220 kernel/kthread.c:292
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:296

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 PID: 3249 Comm: kworker/1:1H Not tainted 5.9.0-syzkaller #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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