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BUG: KCSAN: data-race in __blk_mq_sched_dispatch_requests / blk_mq_run_hw_queue

write to 0xffff88810272b810 of 8 bytes by task 230 on cpu 1:
 INIT_LIST_HEAD include/linux/list.h:36 [inline]
 list_splice_init include/linux/list.h:483 [inline]
 __blk_mq_sched_dispatch_requests+0x137/0x290 block/blk-mq-sched.c:308
 blk_mq_sched_dispatch_requests+0x9f/0x110 block/blk-mq-sched.c:360
 __blk_mq_run_hw_queue+0xbc/0x140 block/blk-mq.c:1480
 __blk_mq_delay_run_hw_queue+0x163/0x2f0 block/blk-mq.c:1557
 blk_mq_run_hw_queue+0x22c/0x250 block/blk-mq.c:1610
 blk_mq_run_hw_queues+0x1d1/0x230 block/blk-mq.c:1673
 blk_mq_requeue_work+0x3ff/0x440 block/blk-mq.c:798
 process_one_work+0x402/0x910 kernel/workqueue.c:2297
 worker_thread+0x636/0xae0 kernel/workqueue.c:2444
 kthread+0x262/0x280 kernel/kthread.c:319
 ret_from_fork+0x1f/0x30

read to 0xffff88810272b810 of 8 bytes by task 23629 on cpu 0:
 list_empty_careful include/linux/list.h:319 [inline]
 blk_mq_hctx_has_pending block/blk-mq.c:72 [inline]
 blk_mq_run_hw_queue+0x129/0x250 block/blk-mq.c:1606
 blk_mq_submit_bio+0xbc3/0xe90 block/blk-mq.c:2215
 __submit_bio_noacct_mq block/blk-core.c:998 [inline]
 submit_bio_noacct+0x6e2/0x7d0 block/blk-core.c:1031
 submit_bio+0x10c/0x190
 submit_bio_wait+0x86/0xc0 block/bio.c:1248
 blkdev_issue_flush+0x7f/0xa0 block/blk-flush.c:458
 ext4_sync_file+0x410/0x670 fs/ext4/fsync.c:177
 vfs_fsync_range+0x107/0x120 fs/sync.c:200
 generic_write_sync include/linux/fs.h:2955 [inline]
 ext4_buffered_write_iter+0x3af/0x400 fs/ext4/file.c:277
 ext4_file_write_iter+0x2e7/0x11f0
 call_write_iter include/linux/fs.h:2163 [inline]
 do_iter_readv_writev+0x2de/0x380 fs/read_write.c:729
 do_iter_write+0x192/0x5c0 fs/read_write.c:855
 vfs_iter_write+0x4c/0x70 fs/read_write.c:896
 iter_file_splice_write+0x43a/0x790 fs/splice.c:689
 do_splice_from fs/splice.c:767 [inline]
 direct_splice_actor+0x80/0xa0 fs/splice.c:936
 splice_direct_to_actor+0x345/0x650 fs/splice.c:891
 do_splice_direct+0x106/0x190 fs/splice.c:979
 do_sendfile+0x63e/0xbb0 fs/read_write.c:1249
 __do_sys_sendfile64 fs/read_write.c:1314 [inline]
 __se_sys_sendfile64 fs/read_write.c:1300 [inline]
 __x64_sys_sendfile64+0x102/0x140 fs/read_write.c:1300
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x44/0xa0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x44/0xae

value changed: 0xffff888101d60048 -> 0xffff88810272b808

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 PID: 23629 Comm: syz-executor.5 Not tainted 5.14.0-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
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