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BUG: KCSAN: data-race in relay_switch_subbuf / relay_switch_subbuf

write to 0xffff8881384b1e38 of 8 bytes by task 31902 on cpu 1:
 relay_switch_subbuf+0x399/0x3a0 kernel/relay.c:708
 relay_reserve include/linux/relay.h:248 [inline]
 __blk_add_trace+0x665/0x720 kernel/trace/blktrace.c:276
 blk_add_trace_bio_remap+0x161/0x170 kernel/trace/blktrace.c:1021
 trace_block_bio_remap include/trace/events/block.h:505 [inline]
 blk_partition_remap block/blk-core.c:550 [inline]
 submit_bio_noacct+0x846/0x8a0 block/blk-core.c:741
 submit_bio+0xb7/0xc0 block/blk-core.c:833
 ext4_io_submit+0x8a/0xa0 fs/ext4/page-io.c:378
 ext4_do_writepages+0xb77/0x21e0 fs/ext4/inode.c:2697
 ext4_writepages+0x15e/0x2e0 fs/ext4/inode.c:2766
 do_writepages+0x1c5/0x340 mm/page-writeback.c:2553
 filemap_fdatawrite_wbc+0xdb/0xf0 mm/filemap.c:393
 __filemap_fdatawrite_range mm/filemap.c:426 [inline]
 filemap_write_and_wait_range+0xe6/0x220 mm/filemap.c:681
 kiocb_invalidate_pages+0x87/0x1e0 mm/filemap.c:2759
 __iomap_dio_rw+0x576/0x10a0 fs/iomap/direct-io.c:554
 iomap_dio_rw+0x40/0x90 fs/iomap/direct-io.c:665
 ext4_dio_write_iter fs/ext4/file.c:609 [inline]
 ext4_file_write_iter+0xab3/0x1230 fs/ext4/file.c:720
 do_iter_write+0x4b4/0x7b0 fs/read_write.c:860
 vfs_writev+0x1a8/0x320 fs/read_write.c:933
 do_pwritev fs/read_write.c:1030 [inline]
 __do_sys_pwritev2 fs/read_write.c:1089 [inline]
 __se_sys_pwritev2+0x10c/0x1d0 fs/read_write.c:1080
 __x64_sys_pwritev2+0x78/0x90 fs/read_write.c:1080
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x41/0xc0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x63/0xcd

write to 0xffff8881384b1e38 of 8 bytes by task 31903 on cpu 0:
 relay_switch_subbuf+0x399/0x3a0 kernel/relay.c:708
 relay_reserve include/linux/relay.h:248 [inline]
 __blk_add_trace+0x665/0x720 kernel/trace/blktrace.c:276
 blk_add_trace_bio kernel/trace/blktrace.c:903 [inline]
 blk_add_trace_getrq+0x12c/0x140 kernel/trace/blktrace.c:940
 trace_block_getrq include/trace/events/block.h:392 [inline]
 blk_mq_submit_bio+0xd08/0xd70 block/blk-mq.c:2976
 __submit_bio+0x11c/0x350 block/blk-core.c:598
 __submit_bio_noacct_mq block/blk-core.c:677 [inline]
 submit_bio_noacct_nocheck+0x4ad/0x5e0 block/blk-core.c:706
 submit_bio_noacct+0x700/0x8a0 block/blk-core.c:800
 submit_bio+0xb7/0xc0 block/blk-core.c:833
 iomap_dio_submit_bio fs/iomap/direct-io.c:77 [inline]
 iomap_dio_bio_iter+0x95f/0xb10 fs/iomap/direct-io.c:347
 __iomap_dio_rw+0x8ac/0x10a0 fs/iomap/direct-io.c:575
 iomap_dio_rw+0x40/0x90 fs/iomap/direct-io.c:665
 ext4_dio_write_iter fs/ext4/file.c:609 [inline]
 ext4_file_write_iter+0xab3/0x1230 fs/ext4/file.c:720
 do_iter_write+0x4b4/0x7b0 fs/read_write.c:860
 vfs_writev+0x1a8/0x320 fs/read_write.c:933
 do_pwritev fs/read_write.c:1030 [inline]
 __do_sys_pwritev2 fs/read_write.c:1089 [inline]
 __se_sys_pwritev2+0x10c/0x1d0 fs/read_write.c:1080
 __x64_sys_pwritev2+0x78/0x90 fs/read_write.c:1080
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x41/0xc0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x63/0xcd

value changed: 0x0000000000000038 -> 0x0000000000000030

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 PID: 31903 Comm: syz-executor.1 Not tainted 6.5.0-rc6-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/26/2023
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