syzbot

loop2: detected capacity change from 0 to 128
vfat: Unknown parameter '����������000000000000000000006ɲ ��	1��s�{���T�6�+��`�N�+�%{a�ZI֝����`��1
�wMOA��y��%(�4�ab�V۾8�_Kׂ(W6
��>�$�B�Z'
==================================================================
BUG: KCSAN: data-race in data_push_tail / number

write to 0xffffffff893c2708 of 1 bytes by task 12636 on cpu 1:
 number+0x865/0xb90 lib/vsprintf.c:573
 vsnprintf+0x64e/0x860 lib/vsprintf.c:2912
 va_format lib/vsprintf.c:1723 [inline]
 pointer+0x821/0xcb0 lib/vsprintf.c:2569
 vsnprintf+0x491/0x860 lib/vsprintf.c:2952
 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
 dev_vprintk_emit+0x242/0x2a0 drivers/base/core.c:4913
 dev_printk_emit+0x84/0xb0 drivers/base/core.c:4924
 __netdev_printk+0x34b/0x370 net/core/dev.c:12932
 netdev_info+0xa6/0xd0 net/core/dev.c:12987
 nsim_udp_tunnel_unset_port+0x190/0x1b0 drivers/net/netdevsim/udp_tunnels.c:59
 udp_tunnel_nic_device_sync_one net/ipv4/udp_tunnel_nic.c:-1 [inline]
 udp_tunnel_nic_device_sync_by_port net/ipv4/udp_tunnel_nic.c:249 [inline]
 __udp_tunnel_nic_device_sync+0x575/0x9b0 net/ipv4/udp_tunnel_nic.c:292
 udp_tunnel_nic_flush+0x21b/0x300 net/ipv4/udp_tunnel_nic.c:694
 udp_tunnel_nic_unregister net/ipv4/udp_tunnel_nic.c:901 [inline]
 udp_tunnel_nic_netdevice_event+0x8c0/0xd70 net/ipv4/udp_tunnel_nic.c:942
 notifier_call_chain kernel/notifier.c:85 [inline]
 raw_notifier_call_chain+0x83/0x1c0 kernel/notifier.c:453
 call_netdevice_notifiers_info net/core/dev.c:2249 [inline]
 call_netdevice_notifiers_extack net/core/dev.c:2287 [inline]
 call_netdevice_notifiers net/core/dev.c:2301 [inline]
 unregister_netdevice_many_notify+0xedb/0x1710 net/core/dev.c:12412
 unregister_netdevice_many net/core/dev.c:12475 [inline]
 unregister_netdevice_queue+0x1cd/0x200 net/core/dev.c:12289
 unregister_netdevice include/linux/netdevice.h:3408 [inline]
 nsim_destroy+0x108/0x480 drivers/net/netdevsim/netdev.c:1182
 __nsim_dev_port_del+0xcf/0x110 drivers/net/netdevsim/dev.c:1528
 nsim_dev_port_del_all drivers/net/netdevsim/dev.c:1540 [inline]
 nsim_dev_reload_destroy+0x1a3/0x2c0 drivers/net/netdevsim/dev.c:1764
 nsim_dev_reload_down+0x67/0x80 drivers/net/netdevsim/dev.c:1038
 devlink_reload+0xad/0x590 net/devlink/dev.c:461
 devlink_pernet_pre_exit+0xdb/0x230 net/devlink/core.c:507
 ops_pre_exit_list net/core/net_namespace.c:161 [inline]
 ops_undo_list+0xb5/0x420 net/core/net_namespace.c:234
 cleanup_net+0x37c/0x5b0 net/core/net_namespace.c:704
 process_one_work kernel/workqueue.c:3275 [inline]
 process_scheduled_works+0x4de/0x9e0 kernel/workqueue.c:3358
 worker_thread+0x581/0x770 kernel/workqueue.c:3439
 kthread+0x22a/0x280 kernel/kthread.c:467
 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 0xffffffff893c2708 of 8 bytes by task 26268 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: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
 logfc+0x2d5/0x2e0 fs/fs_context.c:-1
 vfs_parse_fs_param+0x1e0/0x2a0 fs/fs_context.c:144
 vfs_parse_fs_qstr fs/fs_context.c:173 [inline]
 vfs_parse_fs_string include/linux/fs_context.h:142 [inline]
 vfs_parse_monolithic_sep+0x1e6/0x270 fs/fs_context.c:213
 generic_parse_monolithic+0x24/0x30 fs/fs_context.c:241
 parse_monolithic_mount_data+0x46/0x60 fs/fs_context.c:520
 do_new_mount+0x24e/0x8d0 fs/namespace.c:3835
 path_mount+0x4d0/0xbc0 fs/namespace.c:4159
 do_mount fs/namespace.c:4172 [inline]
 __do_sys_mount fs/namespace.c:4361 [inline]
 __se_sys_mount+0x28c/0x2e0 fs/namespace.c:4338
 __x64_sys_mount+0x67/0x80 fs/namespace.c:4338
 x64_sys_call+0x2d61/0x3020 arch/x86/include/generated/asm/syscalls_64.h:166
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0x12c/0x370 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

value changed: 0x00000000fffff9d2 -> 0x7974205d31202c31

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 UID: 0 PID: 26268 Comm: syz.2.2946 Tainted: G        W           syzkaller #0 PREEMPT(full) 
Tainted: [W]=WARN
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 02/12/2026
==================================================================
lo speed is unknown, defaulting to 1000