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BUG: KCSAN: data-race in relay_switch_subbuf / relay_switch_subbuf

write to 0xffff88813e252238 of 8 bytes by task 23474 on cpu 0:
 relay_switch_subbuf+0x39d/0x3b0 kernel/relay.c:708
 relay_reserve include/linux/relay.h:248 [inline]
 __blk_add_trace+0x6a7/0x700 kernel/trace/blktrace.c:276
 blk_add_trace_plug+0x48/0x60 kernel/trace/blktrace.c:954
 trace_block_plug include/trace/events/block.h:379 [inline]
 blk_add_rq_to_plug+0x2d4/0x390 block/blk-mq.c:1298
 blk_mq_submit_bio+0x90b/0xed0 block/blk-mq.c:2991
 __submit_bio block/blk-core.c:604 [inline]
 __submit_bio_noacct_mq block/blk-core.c:681 [inline]
 submit_bio_noacct_nocheck+0x83d/0xaa0 block/blk-core.c:698
 submit_bio_noacct+0x6a5/0x810 block/blk-core.c:804
 submit_bio+0xfb/0x110 block/blk-core.c:840
 iomap_dio_submit_bio fs/iomap/direct-io.c:77 [inline]
 iomap_dio_bio_iter+0xa0d/0xbd0 fs/iomap/direct-io.c:360
 __iomap_dio_rw+0x981/0x1000 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:587 [inline]
 ext4_file_write_iter+0xa36/0x11b0 fs/ext4/file.c:698
 call_write_iter include/linux/fs.h:2186 [inline]
 new_sync_write fs/read_write.c:491 [inline]
 vfs_write+0x468/0x760 fs/read_write.c:584
 ksys_write+0xe8/0x1a0 fs/read_write.c:637
 __do_sys_write fs/read_write.c:649 [inline]
 __se_sys_write fs/read_write.c:646 [inline]
 __x64_sys_write+0x3e/0x50 fs/read_write.c:646
 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+0x63/0xcd

write to 0xffff88813e252238 of 8 bytes by task 23473 on cpu 1:
 relay_switch_subbuf+0x39d/0x3b0 kernel/relay.c:708
 relay_reserve include/linux/relay.h:248 [inline]
 __blk_add_trace+0x6a7/0x700 kernel/trace/blktrace.c:276
 blk_add_trace_unplug+0x72/0xa0 kernel/trace/blktrace.c:974
 trace_block_unplug include/trace/events/block.h:424 [inline]
 blk_mq_dispatch_plug_list+0x27b/0x2c0 block/blk-mq.c:2757
 blk_mq_flush_plug_list+0x38a/0x3e0 block/blk-mq.c:2800
 blk_add_rq_to_plug+0x142/0x390 block/blk-mq.c:1296
 blk_mq_submit_bio+0x90b/0xed0 block/blk-mq.c:2991
 __submit_bio block/blk-core.c:604 [inline]
 __submit_bio_noacct_mq block/blk-core.c:681 [inline]
 submit_bio_noacct_nocheck+0x83d/0xaa0 block/blk-core.c:698
 submit_bio_noacct+0x6a5/0x810 block/blk-core.c:804
 submit_bio+0xfb/0x110 block/blk-core.c:840
 iomap_dio_submit_bio fs/iomap/direct-io.c:77 [inline]
 iomap_dio_bio_iter+0xa0d/0xbd0 fs/iomap/direct-io.c:360
 __iomap_dio_rw+0x981/0x1000 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:587 [inline]
 ext4_file_write_iter+0xa36/0x11b0 fs/ext4/file.c:698
 call_write_iter include/linux/fs.h:2186 [inline]
 new_sync_write fs/read_write.c:491 [inline]
 vfs_write+0x468/0x760 fs/read_write.c:584
 ksys_write+0xe8/0x1a0 fs/read_write.c:637
 __do_sys_write fs/read_write.c:649 [inline]
 __se_sys_write fs/read_write.c:646 [inline]
 __x64_sys_write+0x3e/0x50 fs/read_write.c:646
 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+0x63/0xcd

value changed: 0x0000000000000038 -> 0x0000000000000030

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 PID: 23473 Comm: syz-executor.3 Not tainted 6.1.0-syzkaller-13139-gf9ff5644bcc0-dirty #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/26/2022
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