EXT4-fs error (device loop3): ext4_map_blocks:783: inode #3: block 2: comm syz.3.4746: lblock 2 mapped to illegal pblock 2 (length 1)
==================================================================
BUG: KCSAN: data-race in data_push_tail / string

write to 0xffffffff88ecb9e8 of 1 bytes by task 15873 on cpu 1:
 string_nocheck lib/vsprintf.c:658 [inline]
 string+0x187/0x220 lib/vsprintf.c:736
 vsnprintf+0x532/0x860 lib/vsprintf.c:2947
 vscnprintf+0x41/0x90 lib/vsprintf.c:3012
 printk_sprint+0x30/0x2d0 kernel/printk/printk.c:2192
 vprintk_store+0x599/0x860 kernel/printk/printk.c:2312
 vprintk_emit+0x15a/0x610 kernel/printk/printk.c:2402
 vprintk_default+0x26/0x30 kernel/printk/printk.c:2441
 vprintk+0x1d/0x30 kernel/printk/printk_safe.c:82
 _printk+0x79/0xa0 kernel/printk/printk.c:2451
 __ext4_error_inode+0x30f/0x3f0 fs/ext4/super.c:848
 __check_block_validity fs/ext4/inode.c:389 [inline]
 ext4_map_blocks+0xa66/0xd20 fs/ext4/inode.c:-1
 ext4_getblk+0x114/0x510 fs/ext4/inode.c:984
 ext4_bread+0x28/0x110 fs/ext4/inode.c:1047
 ext4_quota_write+0x167/0x360 fs/ext4/super.c:7350
 qtree_write_dquot+0x149/0x300 fs/quota/quota_tree.c:462
 v2_write_dquot+0xda/0x140 fs/quota/quota_v2.c:372
 dquot_acquire+0x1c3/0x2b0 fs/quota/dquot.c:473
 ext4_acquire_dquot+0x15f/0x200 fs/ext4/super.c:6982
 dqget+0x527/0x8c0 fs/quota/dquot.c:980
 __dquot_initialize+0x27f/0x7c0 fs/quota/dquot.c:1508
 dquot_initialize+0x1a/0x30 fs/quota/dquot.c:1570
 ext4_process_orphan+0x32/0x1c0 fs/ext4/orphan.c:327
 ext4_orphan_cleanup+0x6a8/0xa00 fs/ext4/orphan.c:472
 __ext4_fill_super fs/ext4/super.c:5658 [inline]
 ext4_fill_super+0x3411/0x37a0 fs/ext4/super.c:5777
 get_tree_bdev_flags+0x291/0x300 fs/super.c:1691
 get_tree_bdev+0x1f/0x30 fs/super.c:1714
 ext4_get_tree+0x1c/0x30 fs/ext4/super.c:5809
 vfs_get_tree+0x57/0x1d0 fs/super.c:1751
 fc_mount fs/namespace.c:1199 [inline]
 do_new_mount_fc fs/namespace.c:3636 [inline]
 do_new_mount+0x24d/0x6a0 fs/namespace.c:3712
 path_mount+0x4ab/0xb80 fs/namespace.c:4022
 do_mount fs/namespace.c:4035 [inline]
 __do_sys_mount fs/namespace.c:4224 [inline]
 __se_sys_mount+0x28c/0x2e0 fs/namespace.c:4201
 __x64_sys_mount+0x67/0x80 fs/namespace.c:4201
 x64_sys_call+0x2cca/0x3000 arch/x86/include/generated/asm/syscalls_64.h:166
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xd8/0x2a0 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

read to 0xffffffff88ecb9e8 of 8 bytes by task 15882 on cpu 0:
 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+0x964/0xb60 kernel/printk/printk_ringbuffer.c:1724
 vprintk_store+0x56d/0x860 kernel/printk/printk.c:2302
 vprintk_emit+0x15a/0x610 kernel/printk/printk.c:2402
 vprintk_default+0x26/0x30 kernel/printk/printk.c:2441
 vprintk+0x1d/0x30 kernel/printk/printk_safe.c:82
 _printk+0x79/0xa0 kernel/printk/printk.c:2451
 __ext4_error_inode+0x30f/0x3f0 fs/ext4/super.c:848
 __check_block_validity fs/ext4/inode.c:389 [inline]
 ext4_map_blocks+0xa66/0xd20 fs/ext4/inode.c:-1
 ext4_getblk+0x114/0x510 fs/ext4/inode.c:984
 ext4_bread+0x28/0x110 fs/ext4/inode.c:1047
 ext4_quota_write+0x167/0x360 fs/ext4/super.c:7350
 qtree_write_dquot+0x149/0x300 fs/quota/quota_tree.c:462
 v2_write_dquot+0xda/0x140 fs/quota/quota_v2.c:372
 dquot_acquire+0x1c3/0x2b0 fs/quota/dquot.c:473
 ext4_acquire_dquot+0x15f/0x200 fs/ext4/super.c:6982
 dqget+0x527/0x8c0 fs/quota/dquot.c:980
 __dquot_initialize+0x27f/0x7c0 fs/quota/dquot.c:1508
 dquot_initialize+0x1a/0x30 fs/quota/dquot.c:1570
 ext4_process_orphan+0x32/0x1c0 fs/ext4/orphan.c:327
 ext4_orphan_cleanup+0x6a8/0xa00 fs/ext4/orphan.c:472
 __ext4_fill_super fs/ext4/super.c:5658 [inline]
 ext4_fill_super+0x3411/0x37a0 fs/ext4/super.c:5777
 get_tree_bdev_flags+0x291/0x300 fs/super.c:1691
 get_tree_bdev+0x1f/0x30 fs/super.c:1714
 ext4_get_tree+0x1c/0x30 fs/ext4/super.c:5809
 vfs_get_tree+0x57/0x1d0 fs/super.c:1751
 fc_mount fs/namespace.c:1199 [inline]
 do_new_mount_fc fs/namespace.c:3636 [inline]
 do_new_mount+0x24d/0x6a0 fs/namespace.c:3712
 path_mount+0x4ab/0xb80 fs/namespace.c:4022
 do_mount fs/namespace.c:4035 [inline]
 __do_sys_mount fs/namespace.c:4224 [inline]
 __se_sys_mount+0x28c/0x2e0 fs/namespace.c:4201
 __x64_sys_mount+0x67/0x80 fs/namespace.c:4201
 x64_sys_call+0x2cca/0x3000 arch/x86/include/generated/asm/syscalls_64.h:166
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xd8/0x2a0 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

value changed: 0x00000000fffff803 -> 0x625f70616d5f3474

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 UID: 0 PID: 15882 Comm: syz.3.4746 Tainted: G        W           syzkaller #0 PREEMPT(voluntary) 
Tainted: [W]=WARN
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/25/2025
==================================================================
EXT4-fs error (device loop3): ext4_map_blocks:783: inode #3: block 48: comm syz.3.4746: lblock 0 mapped to illegal pblock 48 (length 1)
EXT4-fs error (device loop3): ext4_acquire_dquot:6986: comm syz.3.4746: Failed to acquire dquot type 0
EXT4-fs error (device loop3) in ext4_reserve_inode_write:6298: Corrupt filesystem
EXT4-fs error (device loop3): ext4_evict_inode:253: inode #11: comm syz.3.4746: mark_inode_dirty error
EXT4-fs warning (device loop3): ext4_evict_inode:256: couldn't mark inode dirty (err -117)
EXT4-fs (loop3): 1 orphan inode deleted