================================================================== BUG: KCSAN: data-race in relay_switch_subbuf / relay_switch_subbuf write to 0xffff888113816838 of 8 bytes by task 31462 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_plug+0x4c/0x70 kernel/trace/blktrace.c:950 trace_block_plug include/trace/events/block.h:407 [inline] blk_add_rq_to_plug+0x32b/0x3e0 block/blk-mq.c:1290 blk_mq_submit_bio+0xa22/0xd90 block/blk-mq.c:3009 __submit_bio+0x11c/0x370 block/blk-core.c:619 __submit_bio_noacct_mq block/blk-core.c:698 [inline] submit_bio_noacct_nocheck+0x533/0x6d0 block/blk-core.c:727 submit_bio_noacct+0x681/0x830 block/blk-core.c:837 submit_bio+0x218/0x230 block/blk-core.c:879 ext4_io_submit+0x8a/0xb0 fs/ext4/page-io.c:378 ext4_do_writepages+0xb3a/0x2110 fs/ext4/inode.c:2699 ext4_writepages+0x159/0x2e0 fs/ext4/inode.c:2768 do_writepages+0x1d8/0x480 mm/page-writeback.c:2612 filemap_fdatawrite_wbc+0xdb/0x100 mm/filemap.c:397 __filemap_fdatawrite_range mm/filemap.c:430 [inline] file_write_and_wait_range+0xc8/0x170 mm/filemap.c:788 ext4_sync_file+0x134/0x6c0 fs/ext4/fsync.c:158 vfs_fsync_range+0x122/0x140 fs/sync.c:188 generic_write_sync include/linux/fs.h:2793 [inline] ext4_buffered_write_iter+0x338/0x380 fs/ext4/file.c:305 ext4_file_write_iter+0x29f/0xe30 __kernel_write_iter+0x265/0x490 fs/read_write.c:523 dump_emit_page fs/coredump.c:890 [inline] dump_user_range+0x3a7/0x550 fs/coredump.c:951 elf_core_dump+0x1aa6/0x1bc0 fs/binfmt_elf.c:2077 do_coredump+0x1033/0x1890 fs/coredump.c:764 get_signal+0xdc1/0x1080 kernel/signal.c:2896 arch_do_signal_or_restart+0x95/0x4b0 arch/x86/kernel/signal.c:310 exit_to_user_mode_loop kernel/entry/common.c:111 [inline] exit_to_user_mode_prepare include/linux/entry-common.h:328 [inline] irqentry_exit_to_user_mode+0x94/0x130 kernel/entry/common.c:231 irqentry_exit+0x12/0x50 kernel/entry/common.c:334 asm_exc_page_fault+0x26/0x30 arch/x86/include/asm/idtentry.h:623 write to 0xffff888113816838 of 8 bytes by task 29970 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_unplug+0x76/0xb0 kernel/trace/blktrace.c:970 trace_block_unplug include/trace/events/block.h:452 [inline] blk_mq_dispatch_plug_list block/blk-mq.c:2757 [inline] blk_mq_flush_plug_list+0xd17/0xde0 block/blk-mq.c:2817 __blk_flush_plug+0x216/0x280 block/blk-core.c:1188 blk_finish_plug+0x48/0x70 block/blk-core.c:1214 ext4_do_writepages+0x1bd1/0x2110 fs/ext4/inode.c:2730 ext4_writepages+0x159/0x2e0 fs/ext4/inode.c:2768 do_writepages+0x1d8/0x480 mm/page-writeback.c:2612 filemap_fdatawrite_wbc+0xdb/0x100 mm/filemap.c:397 __filemap_fdatawrite_range mm/filemap.c:430 [inline] file_write_and_wait_range+0xc8/0x170 mm/filemap.c:788 ext4_sync_file+0x134/0x6c0 fs/ext4/fsync.c:158 vfs_fsync_range+0x122/0x140 fs/sync.c:188 generic_write_sync include/linux/fs.h:2793 [inline] ext4_buffered_write_iter+0x338/0x380 fs/ext4/file.c:305 ext4_file_write_iter+0x29f/0xe30 __kernel_write_iter+0x265/0x490 fs/read_write.c:523 dump_emit_page fs/coredump.c:890 [inline] dump_user_range+0x3a7/0x550 fs/coredump.c:951 elf_core_dump+0x1aa6/0x1bc0 fs/binfmt_elf.c:2077 do_coredump+0x1033/0x1890 fs/coredump.c:764 get_signal+0xdc1/0x1080 kernel/signal.c:2896 arch_do_signal_or_restart+0x95/0x4b0 arch/x86/kernel/signal.c:310 exit_to_user_mode_loop kernel/entry/common.c:111 [inline] exit_to_user_mode_prepare include/linux/entry-common.h:328 [inline] __syscall_exit_to_user_mode_work kernel/entry/common.c:207 [inline] syscall_exit_to_user_mode+0x59/0x130 kernel/entry/common.c:218 do_syscall_64+0xe2/0x1d0 arch/x86/entry/common.c:89 entry_SYSCALL_64_after_hwframe+0x72/0x7a value changed: 0x0000000000000030 -> 0x0000000000000038 Reported by Kernel Concurrency Sanitizer on: CPU: 0 PID: 29970 Comm: syz-executor.4 Tainted: G W 6.9.0-rc2-syzkaller-00080-gc85af715cac0 #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 03/27/2024 ==================================================================