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BUG: KCSAN: data-race in _prb_read_valid / prb_reserve

write to 0xffffffff86d45b80 of 88 bytes by task 6105 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
 debugfs_start_creating+0x145/0x150 fs/debugfs/inode.c:397
 debugfs_create_dir+0x20/0x230 fs/debugfs/inode.c:572
 hsr_debugfs_init+0x36/0xe0 net/hsr/hsr_debugfs.c:78
 hsr_dev_finalize+0x6a3/0x6d0 net/hsr/hsr_device.c:812
 hsr_newlink+0x5ba/0x650 net/hsr/hsr_netlink.c:128
 rtnl_newlink_create+0x1e4/0x650 net/core/rtnetlink.c:3840
 __rtnl_newlink net/core/rtnetlink.c:3957 [inline]
 rtnl_newlink+0x10a0/0x1330 net/core/rtnetlink.c:4072
 rtnetlink_rcv_msg+0x64b/0x720 net/core/rtnetlink.c:6958
 netlink_rcv_skb+0x123/0x220 net/netlink/af_netlink.c:2550
 rtnetlink_rcv+0x1c/0x30 net/core/rtnetlink.c:6985
 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_sendto+0x470/0x4d0 net/socket.c:2206
 __do_sys_sendto net/socket.c:2213 [inline]
 __se_sys_sendto net/socket.c:2209 [inline]
 __x64_sys_sendto+0x76/0x90 net/socket.c:2209
 x64_sys_call+0x2d35/0x3020 arch/x86/include/generated/asm/syscalls_64.h:45
 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 0xffffffff86d45b80 of 8 bytes by task 6229 on cpu 1:
 desc_read kernel/printk/printk_ringbuffer.c:500 [inline]
 prb_first_seq kernel/printk/printk_ringbuffer.c:2014 [inline]
 _prb_read_valid+0x383/0x950 kernel/printk/printk_ringbuffer.c:2171
 prb_read_valid_info+0x7a/0xa0 kernel/printk/printk_ringbuffer.c:2277
 find_first_fitting_seq+0x1cc/0x330 kernel/printk/printk.c:1567
 syslog_print_all+0x11b/0x3c0 kernel/printk/printk.c:1699
 do_syslog+0x2fd/0x7f0 kernel/printk/printk.c:1777
 __do_sys_syslog kernel/printk/printk.c:1855 [inline]
 __se_sys_syslog kernel/printk/printk.c:1853 [inline]
 __x64_sys_syslog+0x41/0x50 kernel/printk/printk.c:1853
 x64_sys_call+0x2b9e/0x3020 arch/x86/include/generated/asm/syscalls_64.h:104
 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: 0x0000000000003f30 -> 0x0000000000005f30

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 UID: 0 PID: 6229 Comm: syz.6.8961 Tainted: G        W           syzkaller #0 PREEMPT(full) 
Tainted: [W]=WARN
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 02/12/2026
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