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BUG: KCSAN: data-race in blk_mq_run_hw_queue / blk_mq_sched_insert_request

write to 0xffff888129a03010 of 8 bytes by task 2493 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:772
 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

read to 0xffff888129a03010 of 8 bytes by task 7604 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+0x11a/0x1c0 block/blk-mq.c:1504
 blk_mq_sched_insert_requests+0x1ca/0x2e0 block/blk-mq-sched.c:444
 blk_mq_flush_plug_list+0x572/0x6c0 block/blk-mq.c:1772
 blk_flush_plug_list+0x271/0x2a0 block/blk-core.c:1766
 blk_finish_plug block/blk-core.c:1783 [inline]
 blk_finish_plug+0x60/0x84 block/blk-core.c:1779
 fsync_buffers_list fs/buffer.c:720 [inline]
 sync_mapping_buffers+0x317/0x6e0 fs/buffer.c:523
 __generic_file_fsync+0xac/0x190 fs/libfs.c:1005
 ext4_sync_file+0x48e/0xb00 fs/ext4/fsync.c:120
 vfs_fsync_range+0x82/0x150 fs/sync.c:197
 generic_write_sync include/linux/fs.h:2853 [inline]
 ext4_file_write_iter+0x45b/0xa00 fs/ext4/file.c:279
 call_write_iter include/linux/fs.h:1895 [inline]
 do_iter_readv_writev+0x487/0x5b0 fs/read_write.c:693
 do_iter_write fs/read_write.c:970 [inline]
 do_iter_write+0x13b/0x3c0 fs/read_write.c:951
 vfs_iter_write+0x5c/0x80 fs/read_write.c:983

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 PID: 7604 Comm: syz-executor.1 Not tainted 5.4.0-rc3+ #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
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