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BUG: KCSAN: data-race in blk_mq_run_hw_queue / blk_mq_sched_insert_request

read to 0xffff888129715c10 of 8 bytes by task 7880 on cpu 1:
 list_empty_careful include/linux/list.h:287 [inline]
 blk_mq_hctx_has_pending block/blk-mq.c:69 [inline]
 blk_mq_run_hw_queue+0x10e/0x1c0 block/blk-mq.c:1469
 blk_mq_sched_insert_requests+0x198/0x260 block/blk-mq-sched.c:444
 blk_mq_flush_plug_list+0x572/0x6c0 block/blk-mq.c:1733
 blk_flush_plug_list+0x271/0x2a0 block/blk-core.c:1768
 blk_finish_plug block/blk-core.c:1785 [inline]
 blk_finish_plug+0x60/0x84 block/blk-core.c:1781
 ext4_writepages+0xe32/0x2500 fs/ext4/inode.c:2832
 do_writepages+0x6b/0x170 mm/page-writeback.c:2344
 __filemap_fdatawrite_range+0x1c5/0x230 mm/filemap.c:421
 file_write_and_wait_range+0xfd/0x160 mm/filemap.c:782
 ext4_sync_file+0x266/0xaf0 fs/ext4/fsync.c:153
 vfs_fsync_range+0x82/0x150 fs/sync.c:197
 generic_write_sync include/linux/fs.h:2856 [inline]
 ext4_buffered_write_iter+0x222/0x290 fs/ext4/file.c:259
 ext4_file_write_iter+0xf4/0xd40 fs/ext4/file.c:547
 call_write_iter include/linux/fs.h:1902 [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/0x3a0 arch/x86/entry/common.c:294
 entry_SYSCALL_64_after_hwframe+0x44/0xa9

write to 0xffff888129715c10 of 8 bytes by task 2498 on cpu 0:
 __list_add include/linux/list.h:63 [inline]
 list_add include/linux/list.h:79 [inline]
 blk_mq_sched_bypass_insert block/blk-mq-sched.c:367 [inline]
 blk_mq_sched_insert_request+0x2fd/0x3f0 block/blk-mq-sched.c:394
 blk_mq_requeue_work+0x370/0x460 block/blk-mq.c:738
 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

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 PID: 2498 Comm: kworker/0:1H Not tainted 5.5.0-rc1-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Workqueue: kblockd blk_mq_requeue_work
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