EXT4-fs error (device loop9): ext4_validate_block_bitmap:441: comm ext4lazyinit: bg 0: block 112: padding at end of block bitmap is not set
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BUG: KCSAN: data-race in data_push_tail / string

write to 0xffffffff89395aa0 of 1 bytes by task 28 on cpu 0:
 string_nocheck lib/vsprintf.c:659 [inline]
 string+0x187/0x220 lib/vsprintf.c:737
 vsnprintf+0x532/0x860 lib/vsprintf.c:2948
 vscnprintf+0x41/0x90 lib/vsprintf.c:3013
 printk_sprint+0x30/0x2e0 kernel/printk/printk.c:2222
 vprintk_store+0x57b/0x910 kernel/printk/printk.c:2364
 vprintk_emit+0x1a4/0x600 kernel/printk/printk.c:2455
 vprintk_default+0x26/0x30 kernel/printk/printk.c:2494
 vprintk+0x1d/0x30 kernel/printk/printk_safe.c:82
 _printk+0x79/0xa0 kernel/printk/printk.c:2504
 kauditd_printk_skb kernel/audit.c:587 [inline]
 kauditd_hold_skb+0x1b1/0x1c0 kernel/audit.c:622
 kauditd_send_queue+0x273/0x2c0 kernel/audit.c:807
 kauditd_thread+0x444/0x670 kernel/audit.c:931
 kthread+0x22a/0x280 kernel/kthread.c:436
 ret_from_fork+0x150/0x360 arch/x86/kernel/process.c:158
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245

read to 0xffffffff89395aa0 of 8 bytes by task 5730 on cpu 1:
 data_make_reusable kernel/printk/printk_ringbuffer.c:608 [inline]
 data_push_tail+0x100/0x470 kernel/printk/printk_ringbuffer.c:693
 data_alloc+0x11b/0x390 kernel/printk/printk_ringbuffer.c:1089
 prb_reserve+0x8d7/0xae0 kernel/printk/printk_ringbuffer.c:1724
 vprintk_store+0x54a/0x910 kernel/printk/printk.c:2354
 vprintk_emit+0x1a4/0x600 kernel/printk/printk.c:2455
 vprintk_default+0x26/0x30 kernel/printk/printk.c:2494
 vprintk+0x1d/0x30 kernel/printk/printk_safe.c:82
 _printk+0x79/0xa0 kernel/printk/printk.c:2504
 __ext4_error+0x225/0x310 fs/ext4/super.c:823
 ext4_validate_block_bitmap+0x547/0x580 fs/ext4/balloc.c:-1
 ext4_read_block_bitmap_nowait+0x435/0x680 fs/ext4/balloc.c:557
 ext4_mb_init_cache+0x2b8/0xc10 fs/ext4/mballoc.c:1430
 ext4_mb_init_group+0x3d6/0x580 fs/ext4/mballoc.c:1638
 ext4_mb_prefetch_fini+0xf3/0x160 fs/ext4/mballoc.c:2950
 ext4_run_li_request fs/ext4/super.c:3737 [inline]
 ext4_lazyinit_thread+0x3be/0xd00 fs/ext4/super.c:3863
 kthread+0x22a/0x280 kernel/kthread.c:436
 ret_from_fork+0x150/0x360 arch/x86/kernel/process.c:158
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245

value changed: 0x0000000100009063 -> 0x3035393030303030

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 UID: 0 PID: 5730 Comm: ext4lazyinit Tainted: G        W           syzkaller #0 PREEMPT(full) 
Tainted: [W]=WARN
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 03/18/2026
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