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BUG: KCSAN: data-race in relay_switch_subbuf / relay_switch_subbuf

write to 0xffff88813314ce38 of 8 bytes by task 73 on cpu 1:
 relay_switch_subbuf+0x39d/0x3b0 kernel/relay.c:711
 relay_reserve include/linux/relay.h:248 [inline]
 __blk_add_trace+0x6ba/0x710 kernel/trace/blktrace.c:275
 blk_add_trace_rq kernel/trace/blktrace.c:846 [inline]
 blk_add_trace_rq_issue+0x1cd/0x1e0 kernel/trace/blktrace.c:860
 trace_block_rq_issue include/trace/events/block.h:227 [inline]
 blk_mq_start_request+0x273/0x2b0 block/blk-mq.c:1131
 scsi_queue_rq+0x13d8/0x1570 drivers/scsi/scsi_lib.c:1744
 blk_mq_dispatch_rq_list+0x534/0x11f0 block/blk-mq.c:1864
 __blk_mq_sched_dispatch_requests+0x1b4/0x270 block/blk-mq-sched.c:306
 blk_mq_sched_dispatch_requests+0x8f/0xf0 block/blk-mq-sched.c:339
 __blk_mq_run_hw_queue+0x7e/0x100 block/blk-mq.c:1981
 __blk_mq_delay_run_hw_queue+0x194/0x390 block/blk-mq.c:2058
 blk_mq_run_hw_queue+0x180/0x310 block/blk-mq.c:2109
 blk_mq_run_hw_queues+0x1c0/0x240 block/blk-mq.c:2172
 blk_mq_requeue_work+0x3cd/0x400 block/blk-mq.c:1322
 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

write to 0xffff88813314ce38 of 8 bytes by task 5297 on cpu 0:
 relay_switch_subbuf+0x39d/0x3b0 kernel/relay.c:711
 relay_reserve include/linux/relay.h:248 [inline]
 __blk_add_trace+0x6ba/0x710 kernel/trace/blktrace.c:275
 blk_add_trace_plug+0x4a/0x60 kernel/trace/blktrace.c:953
 trace_block_plug include/trace/events/block.h:379 [inline]
 blk_add_rq_to_plug+0x30c/0x390 block/blk-mq.c:2703
 blk_mq_submit_bio+0x91c/0xe40 block/blk-mq.c:2856
 __submit_bio+0x130/0x330 block/blk-core.c:666
 __submit_bio_noacct_mq block/blk-core.c:743 [inline]
 submit_bio_noacct_nocheck+0x3cb/0x480 block/blk-core.c:760
 submit_bio_noacct+0x6c4/0x820 block/blk-core.c:867
 submit_bio+0x139/0x150
 iomap_dio_submit_bio fs/iomap/direct-io.c:67 [inline]
 iomap_dio_bio_iter+0x9ad/0xb60 fs/iomap/direct-io.c:352
 __iomap_dio_rw+0x8c7/0xf80 fs/iomap/direct-io.c:591
 iomap_dio_rw+0x38/0x80 fs/iomap/direct-io.c:681
 ext4_dio_write_iter fs/ext4/file.c:566 [inline]
 ext4_file_write_iter+0x7df/0xdf0 fs/ext4/file.c:677
 do_iter_readv_writev+0x27b/0x300
 do_iter_write+0x16f/0x5c0 fs/read_write.c:852
 vfs_iter_write+0x4c/0x70 fs/read_write.c:893
 iter_file_splice_write+0x44a/0x7c0 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+0x345/0x660 fs/splice.c:891
 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+0x44/0xae

value changed: 0x0000000000000038 -> 0x0000000000000030

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 PID: 5297 Comm: syz-executor.5 Tainted: G        W         5.18.0-rc4-syzkaller-dirty #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
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