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BUG: KCSAN: data-race in dd_has_work / dd_insert_request

write to 0xffff88810323e098 of 8 bytes by task 21210 on cpu 0:
 __list_add include/linux/list.h:72 [inline]
 list_add_tail include/linux/list.h:102 [inline]
 dd_insert_request+0x438/0x570 block/mq-deadline.c:759
 dd_insert_requests+0xfc/0x140 block/mq-deadline.c:778
 blk_mq_sched_insert_requests+0xc0/0x2a0 block/blk-mq-sched.c:477
 blk_mq_dispatch_plug_list+0x1e9/0x2c0 block/blk-mq.c:2648
 blk_mq_flush_plug_list+0x2ea/0x340 block/blk-mq.c:2690
 __blk_flush_plug+0x25a/0x2b0 block/blk-core.c:1219
 blk_finish_plug+0x44/0x60 block/blk-core.c:1243
 ext4_writepages+0x172d/0x1d00 fs/ext4/inode.c:2867
 do_writepages+0x1db/0x350 mm/page-writeback.c:2352
 filemap_fdatawrite_wbc+0xd6/0xf0 mm/filemap.c:388
 __filemap_fdatawrite_range mm/filemap.c:421 [inline]
 filemap_write_and_wait_range+0xbf/0x2e0 mm/filemap.c:673
 __iomap_dio_rw+0x51e/0xf50 fs/iomap/direct-io.c:572
 iomap_dio_rw+0x3c/0x80 fs/iomap/direct-io.c:689
 ext4_dio_read_iter fs/ext4/file.c:79 [inline]
 ext4_file_read_iter+0x22d/0x2a0 fs/ext4/file.c:130
 call_read_iter include/linux/fs.h:2035 [inline]
 generic_file_splice_read+0x1de/0x2c0 fs/splice.c:311
 do_splice_to fs/splice.c:796 [inline]
 splice_direct_to_actor+0x2ac/0x660 fs/splice.c:870
 do_splice_direct+0xfb/0x180 fs/splice.c:979
 do_sendfile+0x3ad/0x900 fs/read_write.c:1246
 __do_sys_sendfile64 fs/read_write.c:1311 [inline]
 __se_sys_sendfile64 fs/read_write.c:1297 [inline]
 __x64_sys_sendfile64+0x10c/0x150 fs/read_write.c:1297
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x2b/0x70 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x46/0xb0

read to 0xffff88810323e098 of 8 bytes by task 155 on cpu 1:
 list_empty_careful include/linux/list.h:329 [inline]
 dd_has_work_for_prio block/mq-deadline.c:838 [inline]
 dd_has_work+0x188/0x260 block/mq-deadline.c:847
 __blk_mq_do_dispatch_sched block/blk-mq-sched.c:109 [inline]
 blk_mq_do_dispatch_sched+0x148/0x780 block/blk-mq-sched.c:187
 __blk_mq_sched_dispatch_requests+0x1ca/0x270
 blk_mq_sched_dispatch_requests+0x8f/0xf0 block/blk-mq-sched.c:339
 __blk_mq_run_hw_queue+0x7e/0x100 block/blk-mq.c:2025
 blk_mq_run_work_fn+0x3d/0x50 block/blk-mq.c:2363
 process_one_work+0x3d3/0x720 kernel/workqueue.c:2289
 worker_thread+0x618/0xa70 kernel/workqueue.c:2436
 kthread+0x1a9/0x1e0 kernel/kthread.c:376
 ret_from_fork+0x1f/0x30

value changed: 0xffff88810323e090 -> 0xffff888103314488

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 PID: 155 Comm: kworker/1:1H Tainted: G        W         5.18.0-syzkaller-07496-gd7227785e384-dirty #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Workqueue: kblockd blk_mq_run_work_fn
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