EXT4-fs error (device loop4): mb_free_blocks:2017: group 0, inode 12: block 14:freeing already freed block (bit 14); block bitmap corrupt.
EXT4-fs error (device loop4): ext4_do_update_inode:5653: inode #12: comm syz.4.1834: corrupted inode contents
==================================================================
BUG: KCSAN: data-race in data_push_tail / vsnprintf

write to 0xffffffff88e3bf8f of 24 bytes by task 9923 on cpu 1:
 vsnprintf+0x2ce/0x890 lib/vsprintf.c:2878
 va_format lib/vsprintf.c:1728 [inline]
 pointer+0x833/0xcf0 lib/vsprintf.c:2548
 vsnprintf+0x491/0x890 lib/vsprintf.c:2930
 vscnprintf+0x41/0x90 lib/vsprintf.c:2991
 printk_sprint+0x30/0x2d0 kernel/printk/printk.c:2216
 vprintk_store+0x599/0x860 kernel/printk/printk.c:2336
 vprintk_emit+0x178/0x650 kernel/printk/printk.c:2426
 vprintk_default+0x26/0x30 kernel/printk/printk.c:2465
 vprintk+0x1d/0x30 kernel/printk/printk_safe.c:82
 _printk+0x79/0xa0 kernel/printk/printk.c:2475
 __ext4_error_inode+0x2ca/0x3f0 fs/ext4/super.c:844
 ext4_do_update_inode fs/ext4/inode.c:5653 [inline]
 ext4_mark_iloc_dirty+0x35e/0xda0 fs/ext4/inode.c:6303
 __ext4_mark_inode_dirty+0x2e2/0x3f0 fs/ext4/inode.c:6509
 ext4_truncate+0x8e5/0xae0 fs/ext4/inode.c:4666
 ext4_process_orphan+0x110/0x1c0 fs/ext4/orphan.c:339
 ext4_orphan_cleanup+0x6a8/0xa00 fs/ext4/orphan.c:474
 __ext4_fill_super fs/ext4/super.c:5609 [inline]
 ext4_fill_super+0x3260/0x35d0 fs/ext4/super.c:5728
 get_tree_bdev_flags+0x28e/0x300 fs/super.c:1692
 get_tree_bdev+0x1f/0x30 fs/super.c:1715
 ext4_get_tree+0x1c/0x30 fs/ext4/super.c:5760
 vfs_get_tree+0x57/0x1d0 fs/super.c:1815
 do_new_mount+0x207/0x5e0 fs/namespace.c:3808
 path_mount+0x4a4/0xb20 fs/namespace.c:4123
 do_mount fs/namespace.c:4136 [inline]
 __do_sys_mount fs/namespace.c:4347 [inline]
 __se_sys_mount+0x28f/0x2e0 fs/namespace.c:4324
 __x64_sys_mount+0x67/0x80 fs/namespace.c:4324
 x64_sys_call+0x2b4d/0x2ff0 arch/x86/include/generated/asm/syscalls_64.h:166
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xd2/0x200 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

read to 0xffffffff88e3bfa0 of 8 bytes by task 9933 on cpu 0:
 data_make_reusable kernel/printk/printk_ringbuffer.c:594 [inline]
 data_push_tail+0xfd/0x420 kernel/printk/printk_ringbuffer.c:679
 data_alloc+0xbf/0x2b0 kernel/printk/printk_ringbuffer.c:1054
 prb_reserve+0x808/0xaf0 kernel/printk/printk_ringbuffer.c:1669
 vprintk_store+0x56d/0x860 kernel/printk/printk.c:2326
 vprintk_emit+0x178/0x650 kernel/printk/printk.c:2426
 vprintk_default+0x26/0x30 kernel/printk/printk.c:2465
 vprintk+0x1d/0x30 kernel/printk/printk_safe.c:82
 _printk+0x79/0xa0 kernel/printk/printk.c:2475
 __ext4_error_inode+0x2ca/0x3f0 fs/ext4/super.c:844
 ext4_do_update_inode fs/ext4/inode.c:5653 [inline]
 ext4_mark_iloc_dirty+0x35e/0xda0 fs/ext4/inode.c:6303
 __ext4_mark_inode_dirty+0x2e2/0x3f0 fs/ext4/inode.c:6509
 ext4_dirty_inode+0x92/0xc0 fs/ext4/inode.c:6538
 __mark_inode_dirty+0x15f/0x750 fs/fs-writeback.c:2527
 mark_inode_dirty_sync include/linux/fs.h:2615 [inline]
 dquot_free_space include/linux/quotaops.h:380 [inline]
 dquot_free_block include/linux/quotaops.h:390 [inline]
 ext4_mb_clear_bb fs/ext4/mballoc.c:6640 [inline]
 ext4_free_blocks+0xea9/0x1480 fs/ext4/mballoc.c:6760
 ext4_remove_blocks fs/ext4/extents.c:2551 [inline]
 ext4_ext_rm_leaf fs/ext4/extents.c:2716 [inline]
 ext4_ext_remove_space+0x177b/0x2900 fs/ext4/extents.c:2965
 ext4_ext_truncate+0xc7/0x170 fs/ext4/extents.c:4484
 ext4_truncate+0x70d/0xae0 fs/ext4/inode.c:4643
 ext4_process_orphan+0x110/0x1c0 fs/ext4/orphan.c:339
 ext4_orphan_cleanup+0x6a8/0xa00 fs/ext4/orphan.c:474
 __ext4_fill_super fs/ext4/super.c:5609 [inline]
 ext4_fill_super+0x3260/0x35d0 fs/ext4/super.c:5728
 get_tree_bdev_flags+0x28e/0x300 fs/super.c:1692
 get_tree_bdev+0x1f/0x30 fs/super.c:1715
 ext4_get_tree+0x1c/0x30 fs/ext4/super.c:5760
 vfs_get_tree+0x57/0x1d0 fs/super.c:1815
 do_new_mount+0x207/0x5e0 fs/namespace.c:3808
 path_mount+0x4a4/0xb20 fs/namespace.c:4123
 do_mount fs/namespace.c:4136 [inline]
 __do_sys_mount fs/namespace.c:4347 [inline]
 __se_sys_mount+0x28f/0x2e0 fs/namespace.c:4324
 __x64_sys_mount+0x67/0x80 fs/namespace.c:4324
 x64_sys_call+0x2b4d/0x2ff0 arch/x86/include/generated/asm/syscalls_64.h:166
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xd2/0x200 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

value changed: 0x00000000fffff298 -> 0x0a737473746e6574

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 UID: 0 PID: 9933 Comm: syz.4.1834 Not tainted syzkaller #0 PREEMPT(voluntary) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 08/18/2025
==================================================================
EXT4-fs error (device loop4): ext4_dirty_inode:6538: inode #12: comm syz.4.1834: mark_inode_dirty error
EXT4-fs error (device loop4): ext4_do_update_inode:5653: inode #12: comm syz.4.1834: corrupted inode contents
EXT4-fs error (device loop4): __ext4_ext_dirty:206: inode #12: comm syz.4.1834: mark_inode_dirty error
EXT4-fs error (device loop4): ext4_do_update_inode:5653: inode #12: comm syz.4.1834: corrupted inode contents
EXT4-fs error (device loop4) in ext4_orphan_del:305: Corrupt filesystem
EXT4-fs error (device loop4): ext4_do_update_inode:5653: inode #12: comm syz.4.1834: corrupted inode contents
EXT4-fs error (device loop4): ext4_truncate:4666: inode #12: comm syz.4.1834: mark_inode_dirty error
EXT4-fs error (device loop4) in ext4_process_orphan:347: Corrupt filesystem
EXT4-fs (loop4): 1 truncate cleaned up
EXT4-fs (loop4): re-mounted 00000000-0000-0000-0000-000000000000 ro.