loop3: detected capacity change from 0 to 512
EXT4-fs: Ignoring removed oldalloc option
EXT4-fs error (device loop3): mb_free_blocks:2049: group 0, inode 11: block 64:
==================================================================
BUG: KCSAN: data-race in data_push_tail / vsnprintf

write to 0xffffffff895c1573 of 22 bytes by task 20336 on cpu 1:
 vsnprintf+0x2c0/0x8c0 lib/vsprintf.c:2900
 va_format lib/vsprintf.c:1725 [inline]
 pointer+0x844/0xc90 lib/vsprintf.c:2577
 vsnprintf+0x49e/0x8c0 lib/vsprintf.c:2953
 vscnprintf+0x41/0x90 lib/vsprintf.c:3018
 printk_sprint+0x30/0x2b0 kernel/printk/printk.c:2222
 vprintk_store+0x57f/0x910 kernel/printk/printk.c:2364
 vprintk_emit+0x1a4/0x610 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_msg+0x1aa/0x1c0 fs/ext4/super.c:1001
 ext4_put_super+0x90/0x7c0 fs/ext4/super.c:1302
 generic_shutdown_super+0xee/0x220 fs/super.c:769
 kill_block_super+0x2d/0xb0 fs/super.c:1918
 ext4_kill_sb+0x42/0x80 fs/ext4/super.c:7527
 deactivate_locked_super+0x75/0x200 fs/super.c:603
 deactivate_super+0x9a/0xb0 fs/super.c:632
 cleanup_mnt+0x2c3/0x340 fs/namespace.c:1317
 __cleanup_mnt+0x19/0x20 fs/namespace.c:1324
 task_work_run+0x130/0x1a0 kernel/task_work.c:233
 resume_user_mode_work include/linux/resume_user_mode.h:50 [inline]
 __exit_to_user_mode_loop kernel/entry/common.c:70 [inline]
 exit_to_user_mode_loop+0x1e4/0x8c0 kernel/entry/common.c:101
 __exit_to_user_mode_prepare include/linux/irq-entry-common.h:207 [inline]
 syscall_exit_to_user_mode_prepare include/linux/irq-entry-common.h:230 [inline]
 syscall_exit_to_user_mode include/linux/entry-common.h:336 [inline]
 do_syscall_64+0x212/0x360 arch/x86/entry/syscall_64.c:89
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

read to 0xffffffff895c1588 of 8 bytes by task 25951 on cpu 0:
 data_make_reusable kernel/printk/printk_ringbuffer.c:608 [inline]
 data_push_tail+0x104/0x440 kernel/printk/printk_ringbuffer.c:693
 data_realloc kernel/printk/printk_ringbuffer.c:1193 [inline]
 prb_reserve_in_last+0x86c/0xae0 kernel/printk/printk_ringbuffer.c:1498
 vprintk_store+0x45b/0x910 kernel/printk/printk.c:2328
 vprintk_emit+0x1a4/0x610 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_grp_locked_error+0x5d8/0x7a0 fs/ext4/super.c:1074
 mb_free_blocks+0xb48/0xb80 fs/ext4/mballoc.c:2046
 ext4_mb_clear_bb fs/ext4/mballoc.c:6651 [inline]
 ext4_free_blocks+0xd4d/0x1430 fs/ext4/mballoc.c:6783
 ext4_clear_blocks+0x2a2/0x2c0 fs/ext4/indirect.c:888
 ext4_free_data fs/ext4/indirect.c:949 [inline]
 ext4_ind_truncate+0x394/0x840 fs/ext4/indirect.c:1154
 ext4_truncate+0x690/0xa50 fs/ext4/inode.c:4700
 ext4_process_orphan+0x10b/0x1c0 fs/ext4/orphan.c:338
 ext4_orphan_cleanup+0x753/0xab0 fs/ext4/orphan.c:473
 __ext4_fill_super fs/ext4/super.c:5726 [inline]
 ext4_fill_super+0x33ea/0x37b0 fs/ext4/super.c:5855
 get_tree_bdev_flags+0x291/0x300 fs/super.c:1887
 get_tree_bdev+0x1f/0x30 fs/super.c:1910
 ext4_get_tree+0x1c/0x30 fs/ext4/super.c:5887
 vfs_get_tree+0x57/0x1d0 fs/super.c:1947
 fc_mount fs/namespace.c:1198 [inline]
 do_new_mount_fc fs/namespace.c:3772 [inline]
 do_new_mount+0x288/0x8d0 fs/namespace.c:3848
 path_mount+0x4ad/0xb90 fs/namespace.c:4168
 do_mount fs/namespace.c:4181 [inline]
 __do_sys_mount fs/namespace.c:4397 [inline]
 __se_sys_mount+0x28c/0x2e0 fs/namespace.c:4374
 __x64_sys_mount+0x67/0x80 fs/namespace.c:4374
 x64_sys_call+0xc3b/0x2550 arch/x86/include/generated/asm/syscalls_64.h:166
 do_syscall_x64 arch/x86/entry/syscall_64.c:61 [inline]
 do_syscall_64+0x112/0x360 arch/x86/entry/syscall_64.c:84
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

value changed: 0x0000000000001795 -> 0x2d30303030303030

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 UID: 0 PID: 25951 Comm: syz.3.3497 Not tainted syzkaller #0 PREEMPT(lazy) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/24/2026
==================================================================
freeing already freed block (bit 63); block bitmap corrupt.
EXT4-fs error (device loop3): ext4_do_update_inode:5801: inode #11: comm syz.3.3497: corrupted inode contents
loop3: lost file I/O error report for ino 11 type 5 pos 0x0 len 0x0 error -117
EXT4-fs error (device loop3): ext4_dirty_inode:6731: inode #11: comm syz.3.3497: mark_inode_dirty error
loop3: lost file I/O error report for ino 11 type 5 pos 0x0 len 0x0 error -117
EXT4-fs error (device loop3): ext4_free_branches:1023: inode #11: comm syz.3.3497: invalid indirect mapped block 1 (level 1)
loop3: lost file I/O error report for ino 11 type 5 pos 0x0 len 0x0 error -117
EXT4-fs error (device loop3): ext4_do_update_inode:5801: inode #11: comm syz.3.3497: corrupted inode contents
loop3: lost file I/O error report for ino 11 type 5 pos 0x0 len 0x0 error -117
EXT4-fs error (device loop3) in ext4_orphan_del:304: Corrupt filesystem
loop3: lost filesystem error report for type 5 error -117
EXT4-fs error (device loop3): ext4_do_update_inode:5801: inode #11: comm syz.3.3497: corrupted inode contents
loop3: lost file I/O error report for ino 11 type 5 pos 0x0 len 0x0 error -117
EXT4-fs error (device loop3): ext4_truncate:4721: inode #11: comm syz.3.3497: mark_inode_dirty error
EXT4-fs error (device loop3) in ext4_process_orphan:346: Corrupt filesystem
loop3: lost filesystem error report for type 5 error -117
EXT4-fs (loop3): 1 truncate cleaned up
EXT4-fs (loop3): mounted filesystem 00000000-0000-0000-0000-000000000000 r/w without journal. Quota mode: writeback.
EXT4-fs error (device loop3): ext4_readdir:270: inode #2: block 13: comm syz.3.3497: path /74/file0: bad entry in directory: directory entry too close to block end - offset=1016, size=1024