loop0: detected capacity change from 0 to 512
EXT4-fs: Quota format mount options ignored when QUOTA feature is enabled
==================================================================
BUG: KCSAN: data-race in data_push_tail / vsnprintf

write to 0xffffffff8912ef90 of 11 bytes by task 12728 on cpu 1:
 vsnprintf+0x2ce/0x860 lib/vsprintf.c:2898
 vscnprintf+0x41/0x90 lib/vsprintf.c:3012
 printk_sprint+0x30/0x2c0 kernel/printk/printk.c:2192
 vprintk_store+0x57b/0x910 kernel/printk/printk.c:2312
 vprintk_emit+0x1a4/0x600 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
 __nla_validate_parse+0x1735/0x1cf0 lib/nlattr.c:647
 __nla_validate+0x40/0x60 lib/nlattr.c:677
 __nla_validate_nested include/net/netlink.h:2313 [inline]
 nla_validate_nested_deprecated include/net/netlink.h:2331 [inline]
 netlbl_cipsov4_add_std net/netlabel/netlabel_cipso_v4.c:161 [inline]
 netlbl_cipsov4_add+0x531/0x12a0 net/netlabel/netlabel_cipso_v4.c:416
 genl_family_rcv_msg_doit+0x187/0x1f0 net/netlink/genetlink.c:1115
 genl_family_rcv_msg net/netlink/genetlink.c:1195 [inline]
 genl_rcv_msg+0x432/0x470 net/netlink/genetlink.c:1210
 netlink_rcv_skb+0x123/0x220 net/netlink/af_netlink.c:2550
 genl_rcv+0x28/0x40 net/netlink/genetlink.c:1219
 netlink_unicast_kernel net/netlink/af_netlink.c:1318 [inline]
 netlink_unicast+0x5c0/0x690 net/netlink/af_netlink.c:1344
 netlink_sendmsg+0x5c8/0x6f0 net/netlink/af_netlink.c:1894
 sock_sendmsg_nosec net/socket.c:727 [inline]
 __sock_sendmsg net/socket.c:742 [inline]
 ____sys_sendmsg+0x5af/0x600 net/socket.c:2592
 ___sys_sendmsg+0x195/0x1e0 net/socket.c:2646
 __sys_sendmsg net/socket.c:2678 [inline]
 __do_sys_sendmsg net/socket.c:2683 [inline]
 __se_sys_sendmsg net/socket.c:2681 [inline]
 __x64_sys_sendmsg+0xd4/0x160 net/socket.c:2681
 x64_sys_call+0x17ba/0x3000 arch/x86/include/generated/asm/syscalls_64.h:47
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xc0/0x2a0 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

read to 0xffffffff8912ef98 of 8 bytes by task 12730 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+0x8d7/0xae0 kernel/printk/printk_ringbuffer.c:1724
 vprintk_store+0x54a/0x910 kernel/printk/printk.c:2302
 vprintk_emit+0x1a4/0x600 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_msg+0x143/0x1c0 fs/ext4/super.c:992
 ext4_check_quota_consistency fs/ext4/super.c:-1 [inline]
 ext4_check_opt_consistency+0xb05/0xb10 fs/ext4/super.c:2816
 __ext4_fill_super fs/ext4/super.c:5350 [inline]
 ext4_fill_super+0x1b5f/0x3800 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+0x288/0x700 fs/namespace.c:3712
 path_mount+0x4d0/0xbc0 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+0xc0/0x2a0 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

value changed: 0x000000010000241d -> 0x7365747962203820

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 UID: 0 PID: 12730 Comm: syz.0.9939 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 (loop0): feature flags set on rev 0 fs, running e2fsck is recommended
EXT4-fs error (device loop0): ext4_mb_mark_diskspace_used:4215: comm syz.0.9939: Allocating blocks 41-42 which overlap fs metadata
EXT4-fs error (device loop0): ext4_acquire_dquot:6986: comm syz.0.9939: Failed to acquire dquot type 1
EXT4-fs error (device loop0): mb_free_blocks:2037: group 0, inode 12: block 14:freeing already freed block (bit 14); block bitmap corrupt.
EXT4-fs error (device loop0): ext4_do_update_inode:5617: inode #12: comm syz.0.9939: corrupted inode contents
EXT4-fs error (device loop0): ext4_dirty_inode:6502: inode #12: comm syz.0.9939: mark_inode_dirty error
EXT4-fs error (device loop0): ext4_do_update_inode:5617: inode #12: comm syz.0.9939: corrupted inode contents
EXT4-fs error (device loop0): __ext4_ext_dirty:206: inode #12: comm syz.0.9939: mark_inode_dirty error
EXT4-fs error (device loop0): ext4_do_update_inode:5617: inode #12: comm syz.0.9939: corrupted inode contents
EXT4-fs error (device loop0) in ext4_orphan_del:303: Corrupt filesystem
EXT4-fs error (device loop0): ext4_do_update_inode:5617: inode #12: comm syz.0.9939: corrupted inode contents
EXT4-fs error (device loop0): ext4_truncate:4635: inode #12: comm syz.0.9939: mark_inode_dirty error
EXT4-fs error (device loop0) in ext4_process_orphan:345: Corrupt filesystem
EXT4-fs (loop0): 1 truncate cleaned up
EXT4-fs (loop0): mounted filesystem 00000000-0000-0000-0000-000000000000 r/w without journal. Quota mode: writeback.