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BUG: KCSAN: data-race in blk_mq_do_dispatch_sched / blk_mq_request_bypass_insert

write to 0xffff8881013fa810 of 8 bytes by task 154 on cpu 1:
 __list_add include/linux/list.h:72 [inline]
 list_add include/linux/list.h:88 [inline]
 blk_mq_request_bypass_insert+0x6a/0x130 block/blk-mq.c:2365
 blk_mq_sched_insert_request+0xfd/0x220 block/blk-mq-sched.c:441
 blk_mq_requeue_work+0x38b/0x3f0 block/blk-mq.c:1318
 process_one_work+0x3e3/0x970 kernel/workqueue.c:2289
 worker_thread+0x638/0xaa0 kernel/workqueue.c:2436
 kthread+0x1c1/0x1e0 kernel/kthread.c:376
 ret_from_fork+0x1f/0x30

read to 0xffff8881013fa810 of 8 bytes by task 12438 on cpu 0:
 list_empty_careful include/linux/list.h:329 [inline]
 __blk_mq_do_dispatch_sched block/blk-mq-sched.c:112 [inline]
 blk_mq_do_dispatch_sched+0x196/0x7f0 block/blk-mq-sched.c:187
 __blk_mq_sched_dispatch_requests+0x1ca/0x270
 blk_mq_sched_dispatch_requests+0x9f/0x110 block/blk-mq-sched.c:339
 __blk_mq_run_hw_queue+0x7e/0x100 block/blk-mq.c:1980
 __blk_mq_delay_run_hw_queue+0x19c/0x390 block/blk-mq.c:2057
 blk_mq_run_hw_queue+0x180/0x310 block/blk-mq.c:2108
 blk_mq_sched_insert_requests+0x1cc/0x2a0 block/blk-mq-sched.c:493
 blk_mq_dispatch_plug_list+0x1e9/0x2c0 block/blk-mq.c:2603
 blk_mq_flush_plug_list+0x2ea/0x340 block/blk-mq.c:2645
 __blk_flush_plug+0x25a/0x2b0 block/blk-core.c:1244
 blk_finish_plug+0x44/0x60 block/blk-core.c:1268
 ext4_writepages+0x1591/0x1a60 fs/ext4/inode.c:2855
 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]
 file_write_and_wait_range+0xd7/0x170 mm/filemap.c:779
 ext4_sync_file+0xad/0x570 fs/ext4/fsync.c:151
 vfs_fsync_range+0x107/0x120 fs/sync.c:188
 generic_write_sync include/linux/fs.h:2732 [inline]
 ext4_buffered_write_iter+0x23f/0x280 fs/ext4/file.c:277
 ext4_file_write_iter+0x21a/0xd70
 call_write_iter include/linux/fs.h:2050 [inline]
 do_iter_readv_writev+0x27d/0x320 fs/read_write.c:726
 do_iter_write+0x192/0x5c0 fs/read_write.c:852
 vfs_iter_write+0x4c/0x70 fs/read_write.c:893
 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+0x675/0xc40 fs/read_write.c:1246
 __do_sys_sendfile64 fs/read_write.c:1305 [inline]
 __se_sys_sendfile64 fs/read_write.c:1297 [inline]
 __x64_sys_sendfile64+0xb9/0x140 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+0x44/0xae

value changed: 0xffff8881013fa808 -> 0xffff888103044848

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 PID: 12438 Comm: syz-executor.4 Not tainted 5.18.0-rc1-syzkaller-00016-g3e732ebf7316-dirty #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
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