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BUG: KCSAN: data-race in relay_switch_subbuf / relay_switch_subbuf

write to 0xffff88813703c838 of 8 bytes by task 4200 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:848 [inline]
 blk_add_trace_rq_issue+0x1be/0x1d0 kernel/trace/blktrace.c:862
 trace_block_rq_issue include/trace/events/block.h:227 [inline]
 blk_mq_start_request+0x23b/0x280 block/blk-mq.c:1134
 scsi_queue_rq+0x13d8/0x1570 drivers/scsi/scsi_lib.c:1744
 blk_mq_dispatch_rq_list+0x544/0x1210 block/blk-mq.c:1896
 __blk_mq_do_dispatch_sched block/blk-mq-sched.c:173 [inline]
 blk_mq_do_dispatch_sched+0x49d/0x7f0 block/blk-mq-sched.c:187
 __blk_mq_sched_dispatch_requests+0x1cd/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:2013
 __blk_mq_delay_run_hw_queue+0x194/0x390 block/blk-mq.c:2090
 blk_mq_run_hw_queue+0x180/0x320 block/blk-mq.c:2141
 blk_mq_sched_insert_requests+0x1cb/0x2a0 block/blk-mq-sched.c:493
 blk_mq_dispatch_plug_list+0x1e9/0x2c0 block/blk-mq.c:2621
 blk_mq_flush_plug_list+0x2ea/0x340 block/blk-mq.c:2663
 __blk_flush_plug+0x25a/0x2b0 block/blk-core.c:1219
 blk_finish_plug+0x44/0x60 block/blk-core.c:1243
 __iomap_dio_rw+0xc6d/0xf50 fs/iomap/direct-io.c:609
 iomap_dio_rw+0x3c/0x80 fs/iomap/direct-io.c:689
 ext4_dio_write_iter fs/ext4/file.c:566 [inline]
 ext4_file_write_iter+0xaa9/0x1210 fs/ext4/file.c:677
 do_iter_readv_writev+0x27b/0x300
 do_iter_write+0x16f/0x5c0 fs/read_write.c:868
 vfs_iter_write+0x4c/0x70 fs/read_write.c:909
 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:1262
 __do_sys_sendfile64 fs/read_write.c:1327 [inline]
 __se_sys_sendfile64 fs/read_write.c:1313 [inline]
 __x64_sys_sendfile64+0x10c/0x150 fs/read_write.c:1313
 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

write to 0xffff88813703c838 of 8 bytes by task 4203 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_bio kernel/trace/blktrace.c:908 [inline]
 blk_add_trace_bio_queue+0x13e/0x150 kernel/trace/blktrace.c:940
 trace_block_bio_queue include/trace/events/block.h:355 [inline]
 submit_bio_noacct+0x7b2/0x7f0 block/blk-core.c:856
 submit_bio+0xfb/0x110
 iomap_dio_submit_bio fs/iomap/direct-io.c:77 [inline]
 iomap_dio_bio_iter+0x9ed/0xba0 fs/iomap/direct-io.c:361
 __iomap_dio_rw+0x8eb/0xf50 fs/iomap/direct-io.c:601
 iomap_dio_rw+0x3c/0x80 fs/iomap/direct-io.c:689
 ext4_dio_write_iter fs/ext4/file.c:566 [inline]
 ext4_file_write_iter+0xaa9/0x1210 fs/ext4/file.c:677
 do_iter_readv_writev+0x27b/0x300
 do_iter_write+0x16f/0x5c0 fs/read_write.c:868
 vfs_iter_write+0x4c/0x70 fs/read_write.c:909
 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:1262
 __do_sys_sendfile64 fs/read_write.c:1327 [inline]
 __se_sys_sendfile64 fs/read_write.c:1313 [inline]
 __x64_sys_sendfile64+0x10c/0x150 fs/read_write.c:1313
 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

value changed: 0x0000000000000040 -> 0x0000000000000030

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 PID: 4203 Comm: syz-executor.0 Not tainted 5.19.0-rc2-syzkaller-00302-g05c6ca8512f2-dirty #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
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