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

write to 0xffff888102be2528 of 8 bytes by task 22429 on cpu 0:
 __list_add include/linux/list.h:70 [inline]
 list_add_tail include/linux/list.h:100 [inline]
 dd_insert_request+0x27a/0x430 block/mq-deadline.c:521
 dd_insert_requests+0x10c/0x150 block/mq-deadline.c:537
 blk_mq_sched_insert_request+0x228/0x240 block/blk-mq-sched.c:448
 blk_mq_submit_bio+0x8b1/0x1060 block/blk-mq.c:2243
 __submit_bio_noacct_mq block/blk-core.c:1014 [inline]
 submit_bio_noacct+0x7c2/0x9a0 block/blk-core.c:1047
 submit_bio+0x200/0x370 block/blk-core.c:1118
 submit_bh_wbc+0x36b/0x3b0 fs/buffer.c:3055
 submit_bh fs/buffer.c:3061 [inline]
 __sync_dirty_buffer+0x136/0x1e0 fs/buffer.c:3156
 sync_dirty_buffer+0x16/0x20 fs/buffer.c:3169
 ext4_write_inode+0x285/0x390 fs/ext4/inode.c:5238
 write_inode+0x8c/0x1f0 fs/fs-writeback.c:1320
 __writeback_single_inode+0x286/0x4d0 fs/fs-writeback.c:1525
 writeback_single_inode+0x122/0x580 fs/fs-writeback.c:1580
 sync_inode fs/fs-writeback.c:2624 [inline]
 sync_inode_metadata+0x52/0x70 fs/fs-writeback.c:2644
 ext4_fsync_nojournal fs/ext4/fsync.c:92 [inline]
 ext4_sync_file+0x359/0x6e0 fs/ext4/fsync.c:170
 vfs_fsync_range+0x107/0x120 fs/sync.c:200
 generic_write_sync include/linux/fs.h:2843 [inline]
 ext4_buffered_write_iter+0x38f/0x3e0 fs/ext4/file.c:277
 ext4_file_write_iter+0x48a/0x10b0 fs/ext4/file.c:502
 call_write_iter include/linux/fs.h:1977 [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+0x7a6/0xe20 fs/read_write.c:1260
 __do_sys_sendfile64 fs/read_write.c:1319 [inline]
 __se_sys_sendfile64 fs/read_write.c:1311 [inline]
 __x64_sys_sendfile64+0xa9/0x130 fs/read_write.c:1311
 do_syscall_64+0x39/0x80 arch/x86/entry/common.c:46
 entry_SYSCALL_64_after_hwframe+0x44/0xae

read to 0xffff888102be2528 of 8 bytes by task 22441 on cpu 1:
 list_empty_careful include/linux/list.h:319 [inline]
 dd_has_work+0xd3/0xe0 block/mq-deadline.c:586
 __blk_mq_do_dispatch_sched block/blk-mq-sched.c:135 [inline]
 blk_mq_do_dispatch_sched+0x138/0x610 block/blk-mq-sched.c:199
 __blk_mq_sched_dispatch_requests+0x1fd/0x2a0 block/blk-mq-sched.c:310
 blk_mq_sched_dispatch_requests+0x9f/0x110 block/blk-mq-sched.c:341
 __blk_mq_run_hw_queue+0xc1/0x140 block/blk-mq.c:1488
 __blk_mq_delay_run_hw_queue+0x188/0x330 block/blk-mq.c:1565
 blk_mq_run_hw_queue+0x231/0x260 block/blk-mq.c:1618
 blk_mq_sched_insert_requests+0x144/0x210 block/blk-mq-sched.c:491
 blk_mq_flush_plug_list+0x2f5/0x400 block/blk-mq.c:1942
 blk_flush_plug_list+0x235/0x260 block/blk-core.c:1749
 blk_finish_plug+0x44/0x60 block/blk-core.c:1766
 ext4_writepages+0x18dd/0x1e70 fs/ext4/inode.c:2853
 do_writepages+0x7b/0x150 mm/page-writeback.c:2352
 __filemap_fdatawrite_range+0x19d/0x1d0 mm/filemap.c:424
 file_write_and_wait_range+0x9f/0x120 mm/filemap.c:763
 ext4_sync_file+0x105/0x6e0 fs/ext4/fsync.c:151
 vfs_fsync_range+0x107/0x120 fs/sync.c:200
 generic_write_sync include/linux/fs.h:2843 [inline]
 ext4_buffered_write_iter+0x38f/0x3e0 fs/ext4/file.c:277
 ext4_file_write_iter+0x48a/0x10b0 fs/ext4/file.c:502
 call_write_iter include/linux/fs.h:1977 [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+0x7a6/0xe20 fs/read_write.c:1260
 __do_sys_sendfile64 fs/read_write.c:1319 [inline]
 __se_sys_sendfile64 fs/read_write.c:1311 [inline]
 __x64_sys_sendfile64+0xa9/0x130 fs/read_write.c:1311
 do_syscall_64+0x39/0x80 arch/x86/entry/common.c:46
 entry_SYSCALL_64_after_hwframe+0x44/0xae

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 PID: 22441 Comm: syz-executor.4 Not tainted 5.12.0-rc5-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
==================================================================