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BUG: KCSAN: data-race in relay_switch_subbuf / relay_switch_subbuf

write to 0xffff88813a75a638 of 8 bytes by task 19082 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_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+0x634/0xdb0 block/blk-mq.c:2834
 __blk_flush_plug+0x210/0x260 block/blk-core.c:1166
 blk_finish_plug+0x47/0x60 block/blk-core.c:1190
 __flush_batch fs/jbd2/checkpoint.c:129 [inline]
 jbd2_log_do_checkpoint+0x611/0xa50 fs/jbd2/checkpoint.c:281
 jbd2_journal_flush+0x15d/0x810 fs/jbd2/journal.c:2457
 ext4_ioctl_checkpoint fs/ext4/ioctl.c:1099 [inline]
 __ext4_ioctl fs/ext4/ioctl.c:1607 [inline]
 ext4_ioctl+0x1fcf/0x2db0 fs/ext4/ioctl.c:1627
 vfs_ioctl fs/ioctl.c:51 [inline]
 __do_sys_ioctl fs/ioctl.c:871 [inline]
 __se_sys_ioctl+0xcf/0x140 fs/ioctl.c:857
 __x64_sys_ioctl+0x43/0x50 fs/ioctl.c:857
 do_syscall_x64 arch/x86/entry/common.c:52 [inline]
 do_syscall_64+0x59/0x120 arch/x86/entry/common.c:83
 entry_SYSCALL_64_after_hwframe+0x63/0x6b

write to 0xffff88813a75a638 of 8 bytes by task 19084 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_bio_queue+0x12c/0x140 kernel/trace/blktrace.c:935
 trace_block_bio_queue include/trace/events/block.h:383 [inline]
 submit_bio_noacct_nocheck+0x57d/0x5e0 block/blk-core.c:698
 submit_bio_noacct+0x67d/0x830 block/blk-core.c:825
 submit_bio+0xb7/0xc0 block/blk-core.c:858
 swap_writepage_bdev_async mm/page_io.c:371 [inline]
 __swap_writepage+0x612/0xc40 mm/page_io.c:389
 swap_writepage+0xa9/0x150 mm/page_io.c:209
 pageout mm/vmscan.c:654 [inline]
 shrink_folio_list+0x196b/0x2570 mm/vmscan.c:1316
 reclaim_folio_list+0x7b/0x1d0 mm/vmscan.c:2101
 reclaim_pages+0x220/0x280 mm/vmscan.c:2137
 madvise_cold_or_pageout_pte_range+0xa89/0xb20 mm/madvise.c:526
 walk_pmd_range mm/pagewalk.c:143 [inline]
 walk_pud_range mm/pagewalk.c:221 [inline]
 walk_p4d_range mm/pagewalk.c:256 [inline]
 walk_pgd_range+0x80a/0xec0 mm/pagewalk.c:293
 __walk_page_range+0xc2/0x320 mm/pagewalk.c:395
 walk_page_range+0x2c7/0x3f0 mm/pagewalk.c:521
 madvise_pageout_page_range mm/madvise.c:585 [inline]
 madvise_pageout mm/madvise.c:612 [inline]
 madvise_vma_behavior mm/madvise.c:1031 [inline]
 madvise_walk_vmas mm/madvise.c:1260 [inline]
 do_madvise+0x1a21/0x25e0 mm/madvise.c:1440
 __do_sys_madvise mm/madvise.c:1453 [inline]
 __se_sys_madvise mm/madvise.c:1451 [inline]
 __x64_sys_madvise+0x60/0x70 mm/madvise.c:1451
 do_syscall_x64 arch/x86/entry/common.c:52 [inline]
 do_syscall_64+0x59/0x120 arch/x86/entry/common.c:83
 entry_SYSCALL_64_after_hwframe+0x63/0x6b

value changed: 0x0000000000000040 -> 0x0000000000000030

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 PID: 19084 Comm: syz-executor.1 Not tainted 6.8.0-rc1-syzkaller-00169-gecb1b8288dc7 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 11/17/2023
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