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BUG: KCSAN: data-race in relay_switch_subbuf / relay_switch_subbuf

write to 0xffff88814a5c0a38 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:147 [inline]
 blk_update_request+0x8fa/0x950 block/blk-mq.c:877
 scsi_end_request+0x52/0x4e0 drivers/scsi/scsi_lib.c:541
 scsi_io_completion+0x9f/0x200 drivers/scsi/scsi_lib.c:978
 scsi_finish_command+0x1bb/0x1d0 drivers/scsi/scsi.c:198
 scsi_complete+0x19a/0x1d0 drivers/scsi/scsi_lib.c:1442
 blk_complete_reqs block/blk-mq.c:1113 [inline]
 blk_done_softirq+0x73/0xa0 block/blk-mq.c:1118
 __do_softirq+0xc1/0x265 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+0x7f/0x90 arch/x86/kernel/irq.c:247
 asm_common_interrupt+0x26/0x40 arch/x86/include/asm/idtentry.h:636
 is_atomic kernel/kcsan/core.c:249 [inline]
 should_watch kernel/kcsan/core.c:277 [inline]
 check_access kernel/kcsan/core.c:752 [inline]
 __tsan_read8+0xe4/0x180 kernel/kcsan/core.c:1025
 do_anonymous_page mm/memory.c:4067 [inline]
 do_pte_missing mm/memory.c:3662 [inline]
 handle_pte_fault mm/memory.c:4939 [inline]
 __handle_mm_fault mm/memory.c:5079 [inline]
 handle_mm_fault+0xa45/0x2c10 mm/memory.c:5233
 faultin_page mm/gup.c:959 [inline]
 __get_user_pages+0x42e/0xd20 mm/gup.c:1258
 __get_user_pages_locked mm/gup.c:1487 [inline]
 __gup_longterm_locked+0xdcb/0x1380 mm/gup.c:2181
 internal_get_user_pages_fast+0x1f99/0x29b0 mm/gup.c:3179
 pin_user_pages_fast+0x92/0xe0 mm/gup.c:3285
 iov_iter_extract_user_pages lib/iov_iter.c:1768 [inline]
 iov_iter_extract_pages+0x284/0x4d0 lib/iov_iter.c:1831
 __bio_iov_iter_get_pages block/bio.c:1276 [inline]
 bio_iov_iter_get_pages+0x338/0xb10 block/bio.c:1349
 iomap_dio_bio_iter+0x706/0xb10 fs/iomap/direct-io.c:317
 __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
 call_write_iter include/linux/fs.h:1877 [inline]
 new_sync_write fs/read_write.c:491 [inline]
 vfs_write+0x4ab/0x7d0 fs/read_write.c:584
 ksys_write+0xeb/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+0x42/0x50 fs/read_write.c:646
 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 0xffff88814a5c0a38 of 8 bytes by task 19097 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:213 [inline]
 dd_insert_request block/mq-deadline.c:823 [inline]
 dd_insert_requests+0x529/0x670 block/mq-deadline.c:877
 blk_mq_dispatch_plug_list block/blk-mq.c:2744 [inline]
 blk_mq_flush_plug_list+0x67f/0xda0 block/blk-mq.c:2799
 blk_add_rq_to_plug+0x108/0x3e0 block/blk-mq.c:1279
 blk_mq_submit_bio+0x692/0xd70 block/blk-mq.c:2994
 __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
 call_write_iter include/linux/fs.h:1877 [inline]
 new_sync_write fs/read_write.c:491 [inline]
 vfs_write+0x4ab/0x7d0 fs/read_write.c:584
 ksys_write+0xeb/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+0x42/0x50 fs/read_write.c:646
 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: 19097 Comm: syz-executor.5 Not tainted 6.5.0-rc6-syzkaller-00036-g4853c74bd7ab #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/26/2023
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