syzbot

==================================================================
BUG: KCSAN: data-race in _prb_read_valid / prb_reserve

write to 0xffffffff86cd92e0 of 88 bytes by task 28565 on cpu 0:
 prb_reserve+0x6e6/0xae0 kernel/printk/printk_ringbuffer.c:1690
 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
 fail_dump lib/fault-inject.c:66 [inline]
 should_fail_ex+0x24b/0x280 lib/fault-inject.c:174
 should_failslab+0x8c/0xb0 mm/failslab.c:46
 slab_pre_alloc_hook mm/slub.c:4454 [inline]
 slab_alloc_node mm/slub.c:4807 [inline]
 kmem_cache_alloc_lru_noprof+0x6c/0x410 mm/slub.c:4849
 sock_alloc_inode+0x34/0xa0 net/socket.c:322
 alloc_inode+0x40/0x170 fs/inode.c:347
 new_inode_pseudo include/linux/fs.h:3003 [inline]
 sock_alloc net/socket.c:637 [inline]
 __sock_create+0x120/0x580 net/socket.c:1569
 sock_create_kern+0x38/0x50 net/socket.c:1681
 udp_sock_create4+0x68/0x2e0 net/ipv4/udp_tunnel_core.c:19
 udp_sock_create include/net/udp_tunnel.h:64 [inline]
 fou_create net/ipv4/fou_core.c:579 [inline]
 fou_nl_add_doit+0xf1/0x6b0 net/ipv4/fou_core.c:764
 genl_family_rcv_msg_doit+0x187/0x1f0 net/netlink/genetlink.c:1114
 genl_family_rcv_msg net/netlink/genetlink.c:1194 [inline]
 genl_rcv_msg+0x432/0x470 net/netlink/genetlink.c:1209
 netlink_rcv_skb+0x123/0x220 net/netlink/af_netlink.c:2550
 genl_rcv+0x28/0x40 net/netlink/genetlink.c:1218
 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+0x194c/0x3020 arch/x86/include/generated/asm/syscalls_64.h:47
 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

read to 0xffffffff86cd92e0 of 8 bytes by task 28566 on cpu 1:
 desc_read kernel/printk/printk_ringbuffer.c:500 [inline]
 desc_read_finalized_seq kernel/printk/printk_ringbuffer.c:1931 [inline]
 prb_read kernel/printk/printk_ringbuffer.c:1979 [inline]
 _prb_read_valid+0x1c4/0x950 kernel/printk/printk_ringbuffer.c:2170
 prb_read_valid+0x3c/0x60 kernel/printk/printk_ringbuffer.c:2242
 __console_flush_and_unlock kernel/printk/printk.c:3392 [inline]
 console_unlock+0x146/0x280 kernel/printk/printk.c:3413
 class_console_lock_destructor include/linux/console.h:736 [inline]
 vcs_open+0x90/0xa0 drivers/tty/vt/vc_screen.c:752
 chrdev_open+0x2eb/0x3a0 fs/char_dev.c:411
 do_dentry_open+0x4ca/0xa90 fs/open.c:949
 vfs_open+0x37/0x1e0 fs/open.c:1081
 do_open fs/namei.c:4671 [inline]
 path_openat+0x1b70/0x2050 fs/namei.c:4830
 do_file_open+0x16c/0x290 fs/namei.c:4859
 do_sys_openat2+0x94/0x130 fs/open.c:1366
 do_sys_open fs/open.c:1372 [inline]
 __do_sys_openat fs/open.c:1388 [inline]
 __se_sys_openat fs/open.c:1383 [inline]
 __x64_sys_openat+0xf2/0x120 fs/open.c:1383
 x64_sys_call+0x1e39/0x3020 arch/x86/include/generated/asm/syscalls_64.h:258
 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: 0x0000000000002b74 -> 0x0000000000004b74

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 UID: 0 PID: 28566 Comm: syz.2.11955 Tainted: G        W           syzkaller #0 PREEMPT(full) 
Tainted: [W]=WARN
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 02/12/2026
==================================================================
bond1: entered promiscuous mode
bond1: entered allmulticast mode
8021q: adding VLAN 0 to HW filter on device bond1
A link change request failed with some changes committed already. Interface bond1 may have been left with an inconsistent configuration, please check.