EXT4-fs (loop4): unmounting filesystem 00000000-0000-0000-0000-000000000000. ================================================================== BUG: KCSAN: data-race in data_push_tail / number write to 0xffffffff88e5e85b of 1 bytes by task 40 on cpu 1: number+0x7f2/0xac0 lib/vsprintf.c:558 vsnprintf+0x6b0/0x8a0 lib/vsprintf.c:2816 vscnprintf+0x42/0x90 lib/vsprintf.c:2917 printk_sprint+0x30/0x2d0 kernel/printk/printk.c:2216 vprintk_store+0x583/0x860 kernel/printk/printk.c:2336 vprintk_emit+0x1a0/0x6c0 kernel/printk/printk.c:2426 vprintk_default+0x26/0x30 kernel/printk/printk.c:2465 vprintk+0x1d/0x30 kernel/printk/printk_safe.c:82 _printk+0x7f/0xb0 kernel/printk/printk.c:2475 bio_check_eod block/blk-core.c:563 [inline] submit_bio_noacct+0x82e/0x930 block/blk-core.c:796 submit_bio+0x218/0x230 block/blk-core.c:916 mpage_bio_submit_write fs/mpage.c:83 [inline] __mpage_writepage+0x821/0xe70 fs/mpage.c:589 write_cache_pages+0x64/0x100 mm/page-writeback.c:2613 mpage_writepages+0x77/0xf0 fs/mpage.c:663 fat_writepages+0x24/0x30 fs/fat/inode.c:199 do_writepages+0x1d8/0x480 mm/page-writeback.c:2656 __writeback_single_inode+0x89/0x850 fs/fs-writeback.c:1680 writeback_sb_inodes+0x458/0xa10 fs/fs-writeback.c:1976 wb_writeback+0x264/0x650 fs/fs-writeback.c:2156 wb_do_writeback fs/fs-writeback.c:2303 [inline] wb_workfn+0x1aa/0x960 fs/fs-writeback.c:2343 process_one_work kernel/workqueue.c:3238 [inline] process_scheduled_works+0x4de/0xa20 kernel/workqueue.c:3319 worker_thread+0x52c/0x710 kernel/workqueue.c:3400 kthread+0x4b7/0x540 kernel/kthread.c:464 ret_from_fork+0x4b/0x60 arch/x86/kernel/process.c:153 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245 read to 0xffffffff88e5e858 of 8 bytes by task 3302 on cpu 0: data_make_reusable kernel/printk/printk_ringbuffer.c:594 [inline] data_push_tail+0x107/0x440 kernel/printk/printk_ringbuffer.c:679 data_alloc+0xbd/0x2c0 kernel/printk/printk_ringbuffer.c:1054 prb_reserve+0x86a/0xb80 kernel/printk/printk_ringbuffer.c:1669 vprintk_store+0x552/0x860 kernel/printk/printk.c:2326 vprintk_emit+0x1a0/0x6c0 kernel/printk/printk.c:2426 vprintk_default+0x26/0x30 kernel/printk/printk.c:2465 vprintk+0x1d/0x30 kernel/printk/printk_safe.c:82 _printk+0x7f/0xb0 kernel/printk/printk.c:2475 __ext4_msg+0x198/0x1b0 fs/ext4/super.c:985 ext4_put_super+0x97/0x910 fs/ext4/super.c:1290 generic_shutdown_super+0xe5/0x220 fs/super.c:642 kill_block_super+0x2a/0x70 fs/super.c:1710 ext4_kill_sb+0x44/0x80 fs/ext4/super.c:7393 deactivate_locked_super+0x7d/0x1c0 fs/super.c:473 deactivate_super+0x9f/0xb0 fs/super.c:506 cleanup_mnt+0x26e/0x2e0 fs/namespace.c:1435 __cleanup_mnt+0x19/0x20 fs/namespace.c:1442 task_work_run+0x13c/0x1b0 kernel/task_work.c:227 resume_user_mode_work include/linux/resume_user_mode.h:50 [inline] exit_to_user_mode_loop kernel/entry/common.c:114 [inline] exit_to_user_mode_prepare include/linux/entry-common.h:329 [inline] __syscall_exit_to_user_mode_work kernel/entry/common.c:207 [inline] syscall_exit_to_user_mode+0xa8/0x120 kernel/entry/common.c:218 do_syscall_64+0xd6/0x1a0 arch/x86/entry/syscall_64.c:100 entry_SYSCALL_64_after_hwframe+0x77/0x7f value changed: 0x00000000ffffe97b -> 0x726e202c3934323d Reported by Kernel Concurrency Sanitizer on: CPU: 0 UID: 0 PID: 3302 Comm: syz-executor Not tainted 6.15.0-rc2-syzkaller-00404-g8560697b23dc #0 PREEMPT(voluntary) Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 02/12/2025 ==================================================================