==================================================================
BUG: KCSAN: data-race in relay_switch_subbuf / relay_switch_subbuf

write to 0xffff888137903638 of 8 bytes by task 4094 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_issue+0x1b6/0x1c0 kernel/trace/blktrace.c:857
 trace_block_rq_issue include/trace/events/block.h:227 [inline]
 blk_mq_start_request+0x215/0x270 block/blk-mq.c:1235
 scsi_queue_rq+0x14cc/0x1a30 drivers/scsi/scsi_lib.c:1762
 blk_mq_dispatch_rq_list+0x7b1/0x11b0 block/blk-mq.c:2035
 __blk_mq_do_dispatch_sched block/blk-mq-sched.c:170 [inline]
 blk_mq_do_dispatch_sched block/blk-mq-sched.c:184 [inline]
 __blk_mq_sched_dispatch_requests+0x69a/0xdd0 block/blk-mq-sched.c:309
 blk_mq_sched_dispatch_requests+0x99/0x100 block/blk-mq-sched.c:333
 blk_mq_run_hw_queue+0x29c/0x4c0 block/blk-mq.c:2249
 blk_mq_flush_plug_list+0xb56/0xda0 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+0x449/0x5e0 block/blk-core.c:706
 submit_bio_noacct+0x75c/0x900 block/blk-core.c:805
 submit_bio+0xb7/0xc0 block/blk-core.c:838
 swap_writepage_bdev_async mm/page_io.c:369 [inline]
 __swap_writepage+0x4bf/0xa00 mm/page_io.c:387
 swap_writepage+0x6e/0x120 mm/page_io.c:207
 pageout mm/vmscan.c:1355 [inline]
 shrink_folio_list+0x195e/0x2550 mm/vmscan.c:2015
 reclaim_folio_list+0x7b/0x1d0 mm/vmscan.c:2801
 reclaim_pages+0x220/0x280 mm/vmscan.c:2837
 madvise_cold_or_pageout_pte_range+0x82c/0x890 mm/madvise.c:529
 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+0x7f4/0xe20 mm/pagewalk.c:293
 __walk_page_range+0xc2/0x320 mm/pagewalk.c:395
 walk_page_range+0x20b/0x330 mm/pagewalk.c:493
 madvise_pageout_page_range mm/madvise.c:587 [inline]
 madvise_pageout mm/madvise.c:614 [inline]
 madvise_vma_behavior mm/madvise.c:1035 [inline]
 madvise_walk_vmas mm/madvise.c:1264 [inline]
 do_madvise+0x1eea/0x29b0 mm/madvise.c:1444
 __do_sys_madvise mm/madvise.c:1457 [inline]
 __se_sys_madvise mm/madvise.c:1455 [inline]
 __x64_sys_madvise+0x60/0x70 mm/madvise.c:1455
 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 0xffff888137903638 of 8 bytes by task 4083 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:381 [inline]
 submit_bio_noacct_nocheck+0x57d/0x5e0 block/blk-core.c:689
 submit_bio_noacct+0x75c/0x900 block/blk-core.c:805
 submit_bio+0xb7/0xc0 block/blk-core.c:838
 swap_writepage_bdev_async mm/page_io.c:369 [inline]
 __swap_writepage+0x4bf/0xa00 mm/page_io.c:387
 swap_writepage+0x6e/0x120 mm/page_io.c:207
 pageout mm/vmscan.c:1355 [inline]
 shrink_folio_list+0x195e/0x2550 mm/vmscan.c:2015
 reclaim_folio_list+0x7b/0x1d0 mm/vmscan.c:2801
 reclaim_pages+0x220/0x280 mm/vmscan.c:2837
 madvise_cold_or_pageout_pte_range+0x82c/0x890 mm/madvise.c:529
 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+0x7f4/0xe20 mm/pagewalk.c:293
 __walk_page_range+0xc2/0x320 mm/pagewalk.c:395
 walk_page_range+0x20b/0x330 mm/pagewalk.c:493
 madvise_pageout_page_range mm/madvise.c:587 [inline]
 madvise_pageout mm/madvise.c:614 [inline]
 madvise_vma_behavior mm/madvise.c:1035 [inline]
 madvise_walk_vmas mm/madvise.c:1264 [inline]
 do_madvise+0x1eea/0x29b0 mm/madvise.c:1444
 __do_sys_madvise mm/madvise.c:1457 [inline]
 __se_sys_madvise mm/madvise.c:1455 [inline]
 __x64_sys_madvise+0x60/0x70 mm/madvise.c:1455
 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: 0x0000000000000040 -> 0x0000000000000030

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 PID: 4083 Comm: syz-executor.2 Not tainted 6.5.0-rc5-syzkaller-00243-g9106536c1aa3 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/26/2023
==================================================================