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BUG: KCSAN: data-race in relay_switch_subbuf / relay_switch_subbuf

write to 0xffff888149c83638 of 8 bytes by interrupt 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_rq kernel/trace/blktrace.c:844 [inline]
 blk_add_trace_rq_complete+0x1b3/0x1c0 kernel/trace/blktrace.c:876
 trace_block_rq_complete include/trace/events/block.h:149 [inline]
 blk_update_request+0x8f4/0x950 block/blk-mq.c:901
 scsi_end_request+0x52/0x4e0 drivers/scsi/scsi_lib.c:537
 scsi_io_completion+0x9f/0x200 drivers/scsi/scsi_lib.c:975
 scsi_finish_command+0x1bb/0x1d0 drivers/scsi/scsi.c:198
 scsi_complete+0x19a/0x1d0 drivers/scsi/scsi_lib.c:1437
 blk_complete_reqs block/blk-mq.c:1136 [inline]
 blk_done_softirq+0x73/0xa0 block/blk-mq.c:1141
 __do_softirq+0xc4/0x27b kernel/softirq.c:553
 invoke_softirq kernel/softirq.c:427 [inline]
 __irq_exit_rcu kernel/softirq.c:632 [inline]
 irq_exit_rcu+0x3b/0x90 kernel/softirq.c:644
 common_interrupt+0x81/0x90 arch/x86/kernel/irq.c:247
 asm_common_interrupt+0x26/0x40 arch/x86/include/asm/idtentry.h:640
 should_watch kernel/kcsan/core.c:280 [inline]
 check_access kernel/kcsan/core.c:752 [inline]
 __tsan_read4+0x113/0x180 kernel/kcsan/core.c:1024
 crc32_body lib/crc32.c:110 [inline]
 crc32_le_generic lib/crc32.c:179 [inline]
 __crc32c_le_base+0x10e/0x520 lib/crc32.c:201
 chksum_update+0x32/0x50 crypto/crc32c_generic.c:88
 crypto_shash_update+0x46/0x50 crypto/shash.c:70
 ext4_chksum fs/ext4/ext4.h:2474 [inline]
 ext4_dirblock_csum fs/ext4/namei.c:382 [inline]
 ext4_dirblock_csum_set fs/ext4/namei.c:430 [inline]
 ext4_handle_dirty_dirblock+0x26d/0x350 fs/ext4/namei.c:438
 add_dirent_to_buf+0x342/0x430 fs/ext4/namei.c:2215
 ext4_add_entry+0x3a6/0x1ec0 fs/ext4/namei.c:2445
 ext4_add_nondir+0x50/0x190 fs/ext4/namei.c:2793
 ext4_symlink+0x4dc/0x590 fs/ext4/namei.c:3434
 vfs_symlink+0xc2/0x1a0 fs/namei.c:4480
 do_symlinkat+0xe3/0x340 fs/namei.c:4506
 __do_sys_symlinkat fs/namei.c:4522 [inline]
 __se_sys_symlinkat fs/namei.c:4519 [inline]
 __x64_sys_symlinkat+0x62/0x70 fs/namei.c:4519
 do_syscall_x64 arch/x86/entry/common.c:52 [inline]
 do_syscall_64+0xcd/0x1d0 arch/x86/entry/common.c:83
 entry_SYSCALL_64_after_hwframe+0x63/0x6b

write to 0xffff888149c83638 of 8 bytes by task 16885 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_rq kernel/trace/blktrace.c:844 [inline]
 blk_add_trace_rq_insert+0x1b6/0x1c0 kernel/trace/blktrace.c:851
 trace_block_rq_insert include/trace/events/block.h:215 [inline]
 dd_insert_request block/mq-deadline.c:824 [inline]
 dd_insert_requests+0x52e/0x670 block/mq-deadline.c:878
 blk_mq_dispatch_plug_list block/blk-mq.c:2784 [inline]
 blk_mq_flush_plug_list+0x634/0xdc0 block/blk-mq.c:2834
 blk_add_rq_to_plug+0x102/0x3d0 block/blk-mq.c:1300
 blk_mq_submit_bio+0x760/0x1020 block/blk-mq.c:3037
 __submit_bio+0x11c/0x350 block/blk-core.c:607
 __submit_bio_noacct_mq block/blk-core.c:686 [inline]
 submit_bio_noacct_nocheck+0x4ad/0x5e0 block/blk-core.c:715
 submit_bio_noacct+0x67d/0x830 block/blk-core.c:825
 submit_bio+0xb7/0xc0 block/blk-core.c:858
 iomap_dio_submit_bio fs/iomap/direct-io.c:80 [inline]
 iomap_dio_bio_iter+0xa4a/0xbe0 fs/iomap/direct-io.c:417
 __iomap_dio_rw+0x8dd/0x1090 fs/iomap/direct-io.c:659
 iomap_dio_rw+0x40/0x90 fs/iomap/direct-io.c:748
 ext4_dio_write_iter fs/ext4/file.c:577 [inline]
 ext4_file_write_iter+0xa8a/0xe10 fs/ext4/file.c:696
 call_write_iter include/linux/fs.h:2085 [inline]
 new_sync_write fs/read_write.c:497 [inline]
 vfs_write+0x760/0x8d0 fs/read_write.c:590
 ksys_write+0xeb/0x1a0 fs/read_write.c:643
 __do_sys_write fs/read_write.c:655 [inline]
 __se_sys_write fs/read_write.c:652 [inline]
 __x64_sys_write+0x42/0x50 fs/read_write.c:652
 do_syscall_x64 arch/x86/entry/common.c:52 [inline]
 do_syscall_64+0xcd/0x1d0 arch/x86/entry/common.c:83
 entry_SYSCALL_64_after_hwframe+0x63/0x6b

value changed: 0x0000000000000038 -> 0x0000000000000030

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 PID: 16885 Comm: syz-executor.1 Not tainted 6.8.0-rc2-syzkaller-00055-g6764c317b6bb #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/25/2024
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