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BUG: KCSAN: data-race in relay_switch_subbuf / relay_switch_subbuf

write to 0xffff8881172f3838 of 8 bytes by task 10882 on cpu 0:
 relay_switch_subbuf+0x39e/0x3b0 kernel/relay.c:708
 relay_reserve include/linux/relay.h:248 [inline]
 __blk_add_trace+0x66a/0x730 kernel/trace/blktrace.c:276
 blk_add_trace_bio_remap+0x165/0x180 kernel/trace/blktrace.c:1021
 trace_block_bio_remap include/trace/events/block.h:507 [inline]
 blk_partition_remap block/blk-core.c:573 [inline]
 submit_bio_noacct+0x7dd/0x830 block/blk-core.c:764
 submit_bio+0x218/0x230 block/blk-core.c:881
 swap_writepage_bdev_async mm/page_io.c:371 [inline]
 __swap_writepage+0x612/0xc50 mm/page_io.c:389
 swap_writepage+0xa9/0x160 mm/page_io.c:209
 shmem_writepage+0x7ac/0x980 mm/shmem.c:1524
 pageout mm/vmscan.c:660 [inline]
 shrink_folio_list+0x1858/0x2460 mm/vmscan.c:1323
 reclaim_folio_list+0x81/0x1e0 mm/vmscan.c:2108
 reclaim_pages+0x227/0x290 mm/vmscan.c:2145
 madvise_cold_or_pageout_pte_range+0xaa0/0xb30 mm/madvise.c:527
 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+0x80d/0xef0 mm/pagewalk.c:293
 __walk_page_range+0xc5/0x330 mm/pagewalk.c:395
 walk_page_range+0x2c5/0x400 mm/pagewalk.c:521
 madvise_pageout_page_range mm/madvise.c:586 [inline]
 madvise_pageout mm/madvise.c:613 [inline]
 madvise_vma_behavior mm/madvise.c:1032 [inline]
 madvise_walk_vmas mm/madvise.c:1261 [inline]
 do_madvise+0x1a38/0x2620 mm/madvise.c:1441
 __do_sys_madvise mm/madvise.c:1454 [inline]
 __se_sys_madvise mm/madvise.c:1452 [inline]
 __x64_sys_madvise+0x61/0x70 mm/madvise.c:1452
 x64_sys_call+0x2825/0x2d30 arch/x86/include/generated/asm/syscalls_64.h:29
 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+0x77/0x7f

write to 0xffff8881172f3838 of 8 bytes by task 2748 on cpu 1:
 relay_switch_subbuf+0x39e/0x3b0 kernel/relay.c:708
 relay_reserve include/linux/relay.h:248 [inline]
 __blk_add_trace+0x66a/0x730 kernel/trace/blktrace.c:276
 blk_add_trace_bio_remap+0x165/0x180 kernel/trace/blktrace.c:1021
 trace_block_bio_remap include/trace/events/block.h:507 [inline]
 blk_partition_remap block/blk-core.c:573 [inline]
 submit_bio_noacct+0x7dd/0x830 block/blk-core.c:764
 submit_bio+0x218/0x230 block/blk-core.c:881
 submit_bh_wbc+0x2de/0x320 fs/buffer.c:2804
 submit_bh+0x1e/0x30 fs/buffer.c:2809
 jbd2_journal_commit_transaction+0x15eb/0x33d0 fs/jbd2/commit.c:731
 kjournald2+0x243/0x430 fs/jbd2/journal.c:201
 kthread+0x1d1/0x210 kernel/kthread.c:388
 ret_from_fork+0x4b/0x60 arch/x86/kernel/process.c:147
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:244

value changed: 0x0000000000000030 -> 0x0000000000000040

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 PID: 2748 Comm: jbd2/sda1-8 Tainted: G        W          6.9.0-rc3-syzkaller-00365-g399f4dae683a #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 03/27/2024
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