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

write to 0xffff888101317318 of 8 bytes by task 32687 on cpu 1:
 __list_add include/linux/list.h:70 [inline]
 list_add_tail include/linux/list.h:100 [inline]
 dd_insert_request block/mq-deadline.c:521 [inline]
 dd_insert_requests+0x38e/0x4f0 block/mq-deadline.c:537
 blk_mq_sched_insert_requests+0xc3/0x210 block/blk-mq-sched.c:486
 blk_mq_flush_plug_list+0x2f5/0x400 block/blk-mq.c:1915
 blk_flush_plug_list+0x235/0x260 block/blk-core.c:1755
 blk_finish_plug+0x44/0x60 block/blk-core.c:1772
 __iomap_dio_rw+0x60f/0x9b0 fs/iomap/direct-io.c:539
 iomap_dio_rw+0x30/0x70 fs/iomap/direct-io.c:605
 ext4_dio_read_iter fs/ext4/file.c:77 [inline]
 ext4_file_read_iter+0x3cd/0x430 fs/ext4/file.c:129
 call_read_iter include/linux/fs.h:1895 [inline]
 generic_file_splice_read+0x22a/0x310 fs/splice.c:311
 do_splice_to fs/splice.c:788 [inline]
 splice_direct_to_actor+0x2aa/0x650 fs/splice.c:867
 do_splice_direct+0xf5/0x170 fs/splice.c:976
 do_sendfile+0x5e0/0xcf0 fs/read_write.c:1257
 __do_sys_sendfile64 fs/read_write.c:1318 [inline]
 __se_sys_sendfile64 fs/read_write.c:1304 [inline]
 __x64_sys_sendfile64+0xf2/0x130 fs/read_write.c:1304
 do_syscall_64+0x39/0x80 arch/x86/entry/common.c:46
 entry_SYSCALL_64_after_hwframe+0x44/0xa9

read to 0xffff888101317318 of 8 bytes by task 32686 on cpu 0:
 list_empty_careful include/linux/list.h:319 [inline]
 dd_has_work+0xc3/0x110 block/mq-deadline.c:589
 __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 block/blk-mq.c:1515 [inline]
 __blk_mq_delay_run_hw_queue+0x207/0x420 block/blk-mq.c:1592
 blk_mq_run_hw_queue+0x231/0x260 block/blk-mq.c:1645
 blk_mq_sched_insert_requests+0x144/0x210 block/blk-mq-sched.c:501
 blk_mq_flush_plug_list+0x2f5/0x400 block/blk-mq.c:1915
 blk_flush_plug_list+0x235/0x260 block/blk-core.c:1755
 blk_finish_plug+0x44/0x60 block/blk-core.c:1772
 ext4_writepages+0x18dd/0x1e70 fs/ext4/inode.c:2852
 do_writepages+0x7b/0x150 mm/page-writeback.c:2352
 __filemap_fdatawrite_range+0x19d/0x1d0 mm/filemap.c:422
 filemap_write_and_wait_range+0x8b/0x2a0 mm/filemap.c:655
 __iomap_dio_rw+0x38c/0x9b0 fs/iomap/direct-io.c:489
 iomap_dio_rw+0x30/0x70 fs/iomap/direct-io.c:605
 ext4_dio_read_iter fs/ext4/file.c:77 [inline]
 ext4_file_read_iter+0x3cd/0x430 fs/ext4/file.c:129
 call_read_iter include/linux/fs.h:1895 [inline]
 generic_file_splice_read+0x22a/0x310 fs/splice.c:311
 do_splice_to fs/splice.c:788 [inline]
 splice_direct_to_actor+0x2aa/0x650 fs/splice.c:867
 do_splice_direct+0xf5/0x170 fs/splice.c:976
 do_sendfile+0x5e0/0xcf0 fs/read_write.c:1257
 __do_sys_sendfile64 fs/read_write.c:1318 [inline]
 __se_sys_sendfile64 fs/read_write.c:1304 [inline]
 __x64_sys_sendfile64+0xf2/0x130 fs/read_write.c:1304
 do_syscall_64+0x39/0x80 arch/x86/entry/common.c:46
 entry_SYSCALL_64_after_hwframe+0x44/0xa9

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 PID: 32686 Comm: syz-executor.5 Not tainted 5.11.0-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
==================================================================