syzbot

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BUG: KCSAN: data-race in data_alloc / prb_reserve

write to 0xffffffff86893918 of 8 bytes by task 22537 on cpu 1:
 data_alloc+0x280/0x2e0 kernel/printk/printk_ringbuffer.c:1102
 prb_reserve+0x807/0xaf0 kernel/printk/printk_ringbuffer.c:1685
 vprintk_store+0x56d/0x860 kernel/printk/printk.c:2299
 vprintk_emit+0x10d/0x580 kernel/printk/printk.c:2399
 vprintk_default+0x26/0x30 kernel/printk/printk.c:2438
 vprintk+0x1d/0x30 kernel/printk/printk_safe.c:82
 _printk+0x79/0xa0 kernel/printk/printk.c:2448
 isofs_read_inode fs/isofs/inode.c:1378 [inline]
 __isofs_iget+0xfe9/0x1100 fs/isofs/inode.c:1519
 isofs_iget fs/isofs/isofs.h:135 [inline]
 isofs_get_blocks+0x185/0x490 fs/isofs/inode.c:1064
 isofs_get_block fs/isofs/inode.c:1117 [inline]
 isofs_bmap fs/isofs/inode.c:1128 [inline]
 isofs_bread+0x5b/0x100 fs/isofs/inode.c:1136
 isofs_find_entry fs/isofs/namei.c:59 [inline]
 isofs_lookup+0x1a8/0x930 fs/isofs/namei.c:165
 __lookup_slow+0x193/0x250 fs/namei.c:1816
 lookup_slow+0x3c/0x60 fs/namei.c:1833
 walk_component+0x1ec/0x220 fs/namei.c:2151
 lookup_last fs/namei.c:2652 [inline]
 path_lookupat+0xfe/0x2a0 fs/namei.c:2676
 filename_lookup+0x147/0x340 fs/namei.c:2705
 user_path_at+0x3e/0x130 fs/namei.c:3215
 __do_sys_pivot_root fs/namespace.c:4567 [inline]
 __se_sys_pivot_root+0x149/0x700 fs/namespace.c:4550
 __x64_sys_pivot_root+0x31/0x40 fs/namespace.c:4550
 x64_sys_call+0x144/0x3000 arch/x86/include/generated/asm/syscalls_64.h:156
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xd2/0x200 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

read to 0xffffffff86893918 of 8 bytes by task 22425 on cpu 0:
 desc_read kernel/printk/printk_ringbuffer.c:479 [inline]
 desc_push_tail kernel/printk/printk_ringbuffer.c:775 [inline]
 desc_reserve kernel/printk/printk_ringbuffer.c:921 [inline]
 prb_reserve+0x220/0xaf0 kernel/printk/printk_ringbuffer.c:1635
 vprintk_store+0x56d/0x860 kernel/printk/printk.c:2299
 vprintk_emit+0x10d/0x580 kernel/printk/printk.c:2399
 vprintk_default+0x26/0x30 kernel/printk/printk.c:2438
 vprintk+0x1d/0x30 kernel/printk/printk_safe.c:82
 _printk+0x79/0xa0 kernel/printk/printk.c:2448
 hsr_debugfs_init+0xa1/0xe0 net/hsr/hsr_debugfs.c:80
 hsr_dev_finalize+0x6a3/0x6d0 net/hsr/hsr_device.c:789
 hsr_newlink+0x5ad/0x640 net/hsr/hsr_netlink.c:128
 rtnl_newlink_create+0x1bc/0x620 net/core/rtnetlink.c:3833
 __rtnl_newlink net/core/rtnetlink.c:3950 [inline]
 rtnl_newlink+0xf29/0x12d0 net/core/rtnetlink.c:4065
 rtnetlink_rcv_msg+0x5fe/0x6d0 net/core/rtnetlink.c:6951
 netlink_rcv_skb+0x123/0x220 net/netlink/af_netlink.c:2552
 rtnetlink_rcv+0x1c/0x30 net/core/rtnetlink.c:6978
 netlink_unicast_kernel net/netlink/af_netlink.c:1320 [inline]
 netlink_unicast+0x5c0/0x690 net/netlink/af_netlink.c:1346
 netlink_sendmsg+0x58b/0x6b0 net/netlink/af_netlink.c:1896
 sock_sendmsg_nosec net/socket.c:727 [inline]
 __sock_sendmsg+0x145/0x180 net/socket.c:742
 __sys_sendto+0x268/0x330 net/socket.c:2244
 __do_sys_sendto net/socket.c:2251 [inline]
 __se_sys_sendto net/socket.c:2247 [inline]
 __x64_sys_sendto+0x76/0x90 net/socket.c:2247
 x64_sys_call+0x2d14/0x3000 arch/x86/include/generated/asm/syscalls_64.h:45
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xd2/0x200 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

value changed: 0x0000000000051360 -> 0x00000000000efdf8

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 UID: 0 PID: 22425 Comm: syz-executor Not tainted syzkaller #0 PREEMPT(voluntary) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/02/2025
==================================================================
Cannot create hsr debugfs directory
netdevsim netdevsim8 netdevsim0: renamed from eth0
netdevsim netdevsim8 netdevsim1: renamed from eth1
netdevsim netdevsim8 netdevsim2: renamed from eth2
netdevsim netdevsim8 netdevsim3: renamed from eth3
8021q: adding VLAN 0 to HW filter on device bond0
8021q: adding VLAN 0 to HW filter on device team0
8021q: adding VLAN 0 to HW filter on device batadv0
veth0_vlan: entered promiscuous mode
veth1_vlan: entered promiscuous mode
veth0_macvtap: entered promiscuous mode
veth1_macvtap: entered promiscuous mode
batman_adv: batadv0: Interface activated: batadv_slave_0
batman_adv: batadv0: Interface activated: batadv_slave_1