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BUG: KCSAN: data-race in relay_switch_subbuf / relay_switch_subbuf

write to 0xffff888024222a38 of 8 bytes by interrupt on cpu 1:
 relay_switch_subbuf+0x336/0x340 kernel/relay.c:796
 relay_reserve include/linux/relay.h:261 [inline]
 __blk_add_trace+0x6db/0x7a0 kernel/trace/blktrace.c:274
 blk_add_trace_rq kernel/trace/blktrace.c:844 [inline]
 blk_add_trace_rq_complete+0x1b6/0x1c0 kernel/trace/blktrace.c:881
 trace_block_rq_complete include/trace/events/block.h:116 [inline]
 blk_update_request+0xabe/0xb00 block/blk-core.c:1436
 scsi_end_request+0x51/0x470 drivers/scsi/scsi_lib.c:583
 scsi_io_completion+0x105/0xf20 drivers/scsi/scsi_lib.c:970
 scsi_finish_command+0x26c/0x2b0 drivers/scsi/scsi.c:214
 scsi_softirq_done+0xdf/0x440 drivers/scsi/scsi_lib.c:1490
 blk_done_softirq+0x145/0x190 block/blk-mq.c:586
 __do_softirq+0x12c/0x2b1 kernel/softirq.c:298
 asm_call_irq_on_stack+0xf/0x20
 __run_on_irqstack arch/x86/include/asm/irq_stack.h:26 [inline]
 run_on_irqstack_cond arch/x86/include/asm/irq_stack.h:77 [inline]
 do_softirq_own_stack+0x32/0x40 arch/x86/kernel/irq_64.c:77
 invoke_softirq kernel/softirq.c:393 [inline]
 __irq_exit_rcu+0xb2/0xc0 kernel/softirq.c:423
 common_interrupt+0xb5/0x130 arch/x86/kernel/irq.c:239
 asm_common_interrupt+0x1e/0x40 arch/x86/include/asm/idtentry.h:622
 get_ctx kernel/kcsan/core.c:198 [inline]
 check_access kernel/kcsan/core.c:629 [inline]
 __tsan_read8+0x108/0x180 kernel/kcsan/core.c:842
 page_zonenum include/linux/mm.h:1086 [inline]
 is_zone_device_page include/linux/mm.h:1092 [inline]
 release_pages+0x144/0x8b0 mm/swap.c:896
 free_pages_and_swap_cache+0x1db/0x1f0 mm/swap_state.c:355
 tlb_batch_pages_flush mm/mmu_gather.c:49 [inline]
 tlb_flush_mmu_free mm/mmu_gather.c:242 [inline]
 tlb_flush_mmu+0x597/0x5f0 mm/mmu_gather.c:249
 zap_pte_range+0x1134/0x13c0 mm/memory.c:1319
 zap_pmd_range mm/memory.c:1357 [inline]
 zap_pud_range mm/memory.c:1386 [inline]
 zap_p4d_range mm/memory.c:1407 [inline]
 unmap_page_range+0x560/0x660 mm/memory.c:1428
 unmap_single_vma+0x157/0x210 mm/memory.c:1473
 unmap_vmas+0xbf/0x150 mm/memory.c:1505
 exit_mmap+0x1c7/0x3b0 mm/mmap.c:3222
 __mmput+0xa2/0x220 kernel/fork.c:1079
 mmput+0x38/0x40 kernel/fork.c:1100
 exit_mm+0x2bd/0x320 kernel/exit.c:483
 do_exit+0x3c2/0x15a0 kernel/exit.c:793
 do_group_exit+0xc8/0x170 kernel/exit.c:903
 get_signal+0xf9b/0x1510 kernel/signal.c:2757
 arch_do_signal+0x25/0x260 arch/x86/kernel/signal.c:811
 exit_to_user_mode_loop kernel/entry/common.c:161 [inline]
 exit_to_user_mode_prepare+0xde/0x170 kernel/entry/common.c:191
 syscall_exit_to_user_mode+0x16/0x30 kernel/entry/common.c:266
 do_syscall_64+0x45/0x80 arch/x86/entry/common.c:56
 entry_SYSCALL_64_after_hwframe+0x44/0xa9

write to 0xffff888024222a38 of 8 bytes by task 15513 on cpu 0:
 relay_switch_subbuf+0x336/0x340 kernel/relay.c:796
 relay_reserve include/linux/relay.h:261 [inline]
 __blk_add_trace+0x6db/0x7a0 kernel/trace/blktrace.c:274
 blk_add_trace_rq kernel/trace/blktrace.c:844 [inline]
 blk_add_trace_rq_insert+0x1b8/0x1d0 kernel/trace/blktrace.c:852
 trace_block_rq_insert include/trace/events/block.h:192 [inline]
 blk_mq_sched_request_inserted+0x90/0xd0 block/blk-mq-sched.c:389
 dd_insert_request block/mq-deadline.c:501 [inline]
 dd_insert_requests+0x1a8/0x4f0 block/mq-deadline.c:537
 blk_mq_sched_insert_requests+0xc3/0x210 block/blk-mq-sched.c:486
 blk_mq_flush_plug_list+0x2f5/0x400 block/blk-mq.c:1932
 blk_flush_plug_list+0x235/0x260 block/blk-core.c:1756
 blk_mq_submit_bio+0x81a/0x1020 block/blk-mq.c:2225
 __submit_bio_noacct_mq block/blk-core.c:1022 [inline]
 submit_bio_noacct+0x77d/0x930 block/blk-core.c:1055
 submit_bio+0x1f3/0x360 block/blk-core.c:1125
 iomap_dio_submit_bio fs/iomap/direct-io.c:76 [inline]
 iomap_dio_bio_actor+0x82d/0xa60 fs/iomap/direct-io.c:312
 iomap_dio_actor+0x266/0x3a0 fs/iomap/direct-io.c:387
 iomap_apply+0x1e1/0x4a0 fs/iomap/apply.c:84
 __iomap_dio_rw+0x448/0x9b0 fs/iomap/direct-io.c:517
 iomap_dio_rw+0x30/0x70 fs/iomap/direct-io.c:605
 ext4_dio_write_iter fs/ext4/file.c:552 [inline]
 ext4_file_write_iter+0xe06/0x1090 fs/ext4/file.c:662
 call_write_iter include/linux/fs.h:1887 [inline]
 aio_write+0x24f/0x310 fs/aio.c:1579
 __io_submit_one fs/aio.c:1838 [inline]
 io_submit_one+0x654/0x1230 fs/aio.c:1881
 __do_sys_io_submit fs/aio.c:1940 [inline]
 __se_sys_io_submit+0xf5/0x270 fs/aio.c:1910
 __x64_sys_io_submit+0x3f/0x50 fs/aio.c:1910
 do_syscall_64+0x39/0x80 arch/x86/entry/common.c:46
 entry_SYSCALL_64_after_hwframe+0x44/0xa9

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 PID: 15513 Comm: //selinux Not tainted 5.9.0-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
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