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BUG: KCSAN: data-race in __blk_mq_sched_dispatch_requests / blk_mq_run_hw_queue

write to 0xffff888129902010 of 8 bytes by task 3222 on cpu 0:
 INIT_LIST_HEAD include/linux/list.h:36 [inline]
 list_splice_init include/linux/list.h:465 [inline]
 __blk_mq_sched_dispatch_requests+0x174/0x2b0 block/blk-mq-sched.c:224
 blk_mq_sched_dispatch_requests+0x9f/0x110 block/blk-mq-sched.c:276
 __blk_mq_run_hw_queue+0xee/0x1c0 block/blk-mq.c:1418
 __blk_mq_delay_run_hw_queue+0x199/0x340 block/blk-mq.c:1495
 blk_mq_run_hw_queue+0x22e/0x260 block/blk-mq.c:1548
 blk_mq_run_hw_queues block/blk-mq.c:1566 [inline]
 blk_mq_requeue_work+0x433/0x4a0 block/blk-mq.c:774
 process_one_work+0x3e1/0x9a0 kernel/workqueue.c:2269
 worker_thread+0x665/0xbe0 kernel/workqueue.c:2415
 kthread+0x20d/0x230 kernel/kthread.c:291
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:293

read to 0xffff888129902010 of 8 bytes by task 10840 on cpu 1:
 list_empty_careful include/linux/list.h:301 [inline]
 blk_mq_hctx_has_pending block/blk-mq.c:70 [inline]
 blk_mq_run_hw_queue+0x12b/0x260 block/blk-mq.c:1544
 blk_mq_make_request+0xa6b/0x1070 block/blk-mq.c:2081
 do_make_request block/blk-core.c:1084 [inline]
 generic_make_request+0x240/0x5d0 block/blk-core.c:1156
 submit_bio+0x200/0x370 block/blk-core.c:1275
 submit_bio_wait+0x88/0x120 block/bio.c:1149
 blkdev_issue_flush+0xd3/0xf0 block/blk-flush.c:448
 ext4_sync_file+0x3eb/0x6e0 fs/ext4/fsync.c:177
 vfs_fsync_range+0x107/0x120 fs/sync.c:200
 generic_write_sync include/linux/fs.h:2882 [inline]
 iomap_dio_complete+0x2de/0x380 fs/iomap/direct-io.c:125
 iomap_dio_rw+0x874/0x8c0 fs/iomap/direct-io.c:572
 ext4_dio_write_iter fs/ext4/file.c:545 [inline]
 ext4_file_write_iter+0xda4/0x1010 fs/ext4/file.c:653
 call_write_iter include/linux/fs.h:1908 [inline]
 do_iter_readv_writev+0x321/0x3c0 fs/read_write.c:713
 do_iter_write+0x10e/0x470 fs/read_write.c:1018
 vfs_iter_write+0x4c/0x70 fs/read_write.c:1059
 iter_file_splice_write+0x41a/0x770 fs/splice.c:750
 do_splice_from fs/splice.c:846 [inline]
 direct_splice_actor+0x95/0x160 fs/splice.c:1016
 splice_direct_to_actor+0x365/0x660 fs/splice.c:971
 do_splice_direct+0xf2/0x170 fs/splice.c:1059
 do_sendfile+0x562/0xb10 fs/read_write.c:1540
 __do_sys_sendfile64 fs/read_write.c:1601 [inline]
 __se_sys_sendfile64 fs/read_write.c:1587 [inline]
 __x64_sys_sendfile64+0xf2/0x130 fs/read_write.c:1587
 do_syscall_64+0x51/0xb0 arch/x86/entry/common.c:384
 entry_SYSCALL_64_after_hwframe+0x44/0xa9

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 PID: 10840 Comm: syz-executor.5 Not tainted 5.8.0-rc5-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
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