==================================================================
BUG: KCSAN: data-race in dd_has_work / deadline_remove_request

write to 0xffff888102046090 of 8 bytes by task 709 on cpu 1:
 __list_del include/linux/list.h:112 [inline]
 __list_del_entry include/linux/list.h:135 [inline]
 list_del_init include/linux/list.h:204 [inline]
 deadline_remove_request+0x58/0x180 block/mq-deadline-main.c:198
 deadline_move_request block/mq-deadline-main.c:274 [inline]
 __dd_dispatch_request+0x3d3/0x4b0 block/mq-deadline-main.c:472
 dd_dispatch_request+0x138/0x1e0 block/mq-deadline-main.c:518
 __blk_mq_do_dispatch_sched block/blk-mq-sched.c:149 [inline]
 blk_mq_do_dispatch_sched+0x1e4/0x640 block/blk-mq-sched.c:214
 __blk_mq_sched_dispatch_requests+0x1eb/0x290 block/blk-mq-sched.c:329
 blk_mq_sched_dispatch_requests+0x9f/0x110 block/blk-mq-sched.c:360
 __blk_mq_run_hw_queue+0xbc/0x140 block/blk-mq.c:1500
 blk_mq_run_work_fn+0x3d/0x50 block/blk-mq.c:1832
 process_one_work+0x3e9/0x8f0 kernel/workqueue.c:2276
 worker_thread+0x636/0xae0 kernel/workqueue.c:2422
 kthread+0x262/0x280 kernel/kthread.c:319
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:295

read to 0xffff888102046090 of 8 bytes by task 30511 on cpu 0:
 list_empty_careful include/linux/list.h:319 [inline]
 dd_has_work_for_prio block/mq-deadline-main.c:841 [inline]
 dd_has_work+0x187/0x260 block/mq-deadline-main.c:850
 blk_mq_sched_has_work block/blk-mq-sched.h:77 [inline]
 blk_mq_hctx_has_pending block/blk-mq.c:74 [inline]
 blk_mq_run_hw_queue+0x19f/0x250 block/blk-mq.c:1626
 blk_mq_submit_bio+0xbaf/0xe80 block/blk-mq.c:2235
 __submit_bio_noacct_mq block/blk-core.c:1011 [inline]
 submit_bio_noacct+0x6f2/0x7e0 block/blk-core.c:1044
 submit_bio+0x10c/0x190 include/linux/vmstat.h:81
 submit_bio_wait+0x86/0xc0 block/bio.c:1155
 blkdev_issue_flush+0x6c/0x90 block/blk-flush.c:445
 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:2987 [inline]
 ext4_buffered_write_iter+0x39c/0x3f0 fs/ext4/file.c:277
 ext4_file_write_iter+0x2e7/0x11d0 fs/ext4/file.c:519
 call_write_iter include/linux/fs.h:2114 [inline]
 do_iter_readv_writev+0x2cb/0x360 fs/read_write.c:740
 do_iter_write+0x112/0x4c0 fs/read_write.c:866
 vfs_iter_write+0x4c/0x70 fs/read_write.c:907
 iter_file_splice_write+0x40a/0x750 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+0xf5/0x170 fs/splice.c:979
 do_sendfile+0x773/0xda0 fs/read_write.c:1260
 __do_sys_sendfile64 fs/read_write.c:1325 [inline]
 __se_sys_sendfile64 fs/read_write.c:1311 [inline]
 __x64_sys_sendfile64+0xf2/0x130 fs/read_write.c:1311
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x3d/0x90 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x44/0xae

value changed: 0xffff888102b45a48 -> 0xffff888102046088

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 PID: 30511 Comm: syz-executor.3 Not tainted 5.14.0-rc1-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
==================================================================