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BUG: KCSAN: data-race in relay_switch_subbuf / relay_switch_subbuf

write to 0xffff88813624c238 of 8 bytes by interrupt on cpu 1:
 relay_switch_subbuf+0x3b5/0x3c0 kernel/relay.c:711
 relay_reserve include/linux/relay.h:248 [inline]
 __blk_add_trace+0x66f/0x740 kernel/trace/blktrace.c:275
 blk_add_trace_rq kernel/trace/blktrace.c:846 [inline]
 blk_add_trace_rq_complete+0x102/0x110 kernel/trace/blktrace.c:879
 trace_block_rq_complete include/trace/events/block.h:147 [inline]
 blk_update_request+0x8c8/0x980 block/blk-mq.c:785
 scsi_end_request+0x52/0x460 drivers/scsi/scsi_lib.c:543
 scsi_io_completion+0xdf/0x1220 drivers/scsi/scsi_lib.c:980
 scsi_finish_command+0x1b8/0x1d0 drivers/scsi/scsi.c:198
 scsi_complete+0x1a5/0x1e0 drivers/scsi/scsi_lib.c:1482
 blk_complete_reqs block/blk-mq.c:1011 [inline]
 blk_done_softirq+0x92/0xc0 block/blk-mq.c:1016
 __do_softirq+0x158/0x2de kernel/softirq.c:558
 __irq_exit_rcu kernel/softirq.c:637 [inline]
 irq_exit_rcu+0x37/0x70 kernel/softirq.c:649
 common_interrupt+0x9f/0xc0 arch/x86/kernel/irq.c:240
 asm_common_interrupt+0x1e/0x40
 kcsan_setup_watchpoint+0x43d/0x460 kernel/kcsan/core.c:694
 follow_page_mask+0x46/0x890 mm/gup.c:833
 __get_user_pages+0x327/0xc50 mm/gup.c:1184
 __get_user_pages_locked mm/gup.c:1378 [inline]
 get_user_pages_unlocked+0x175/0x630 mm/gup.c:2161
 __gup_longterm_unlocked+0x47/0x100 mm/gup.c:2737
 internal_get_user_pages_fast+0x7ca/0x8a0 mm/gup.c:2825
 get_user_pages_fast+0x5d/0x80 mm/gup.c:2917
 iov_iter_get_pages+0x1bd/0x5d0 lib/iov_iter.c:1541
 __bio_iov_iter_get_pages+0xb5/0x760 block/bio.c:1164
 bio_iov_iter_get_pages+0x181/0x300 block/bio.c:1275
 iomap_dio_bio_iter+0x6ad/0xbd0 fs/iomap/direct-io.c:323
 __iomap_dio_rw+0x8d6/0x10a0 fs/iomap/direct-io.c:592
 iomap_dio_rw+0x38/0x80 fs/iomap/direct-io.c:682
 ext4_dio_write_iter fs/ext4/file.c:566 [inline]
 ext4_file_write_iter+0x7ab/0xd70 fs/ext4/file.c:677
 call_write_iter include/linux/fs.h:2081 [inline]
 new_sync_write fs/read_write.c:504 [inline]
 vfs_write+0x7f5/0x950 fs/read_write.c:591
 ksys_write+0xd9/0x190 fs/read_write.c:644
 __do_sys_write fs/read_write.c:656 [inline]
 __se_sys_write fs/read_write.c:653 [inline]
 __x64_sys_write+0x3e/0x50 fs/read_write.c:653
 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+0x44/0xae

write to 0xffff88813624c238 of 8 bytes by task 31160 on cpu 0:
 relay_switch_subbuf+0x3b5/0x3c0 kernel/relay.c:711
 relay_reserve include/linux/relay.h:248 [inline]
 __blk_add_trace+0x66f/0x740 kernel/trace/blktrace.c:275
 blk_add_trace_rq kernel/trace/blktrace.c:846 [inline]
 blk_add_trace_rq_insert+0xf8/0x110 kernel/trace/blktrace.c:854
 trace_block_rq_insert include/trace/events/block.h:213 [inline]
 dd_insert_request+0x4ed/0x530 block/mq-deadline.c:741
 dd_insert_requests+0x10c/0x150 block/mq-deadline.c:777
 blk_mq_sched_insert_requests+0xc1/0x2a0 block/blk-mq-sched.c:477
 blk_mq_dispatch_plug_list+0x1e9/0x2c0 block/blk-mq.c:2604
 blk_mq_flush_plug_list+0x2ea/0x340 block/blk-mq.c:2646
 blk_add_rq_to_plug+0x13f/0x3a0 block/blk-mq.c:2707
 blk_mq_submit_bio+0x99d/0xff0 block/blk-mq.c:2856
 __submit_bio+0x131/0x330 block/blk-core.c:667
 __submit_bio_noacct_mq block/blk-core.c:744 [inline]
 submit_bio_noacct_nocheck+0x475/0x4e0 block/blk-core.c:761
 submit_bio_noacct+0x69d/0x810 block/blk-core.c:872
 submit_bio+0x10c/0x180
 iomap_dio_submit_bio fs/iomap/direct-io.c:67 [inline]
 iomap_dio_bio_iter+0x94d/0xbd0 fs/iomap/direct-io.c:353
 __iomap_dio_rw+0x8d6/0x10a0 fs/iomap/direct-io.c:592
 iomap_dio_rw+0x38/0x80 fs/iomap/direct-io.c:682
 ext4_dio_write_iter fs/ext4/file.c:566 [inline]
 ext4_file_write_iter+0x7ab/0xd70 fs/ext4/file.c:677
 call_write_iter include/linux/fs.h:2081 [inline]
 new_sync_write fs/read_write.c:504 [inline]
 vfs_write+0x7f5/0x950 fs/read_write.c:591
 ksys_write+0xd9/0x190 fs/read_write.c:644
 __do_sys_write fs/read_write.c:656 [inline]
 __se_sys_write fs/read_write.c:653 [inline]
 __x64_sys_write+0x3e/0x50 fs/read_write.c:653
 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+0x44/0xae

value changed: 0x0000000000000038 -> 0x0000000000000030

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 PID: 31160 Comm: syz-executor.0 Not tainted 5.17.0-syzkaller-02003-g3bf03b9a0839-dirty #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
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