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BUG: KCSAN: data-race in _prb_read_valid / data_alloc

write to 0xffffffff86c6a680 of 8 bytes by task 12195 on cpu 1:
 data_alloc+0x310/0x390 kernel/printk/printk_ringbuffer.c:1129
 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
 br_set_state+0x2ae/0x3b0 net/bridge/br_stp.c:57
 br_stp_disable_port+0x5d/0x150 net/bridge/br_stp_if.c:106
 del_nbp+0xd2/0x720 net/bridge/br_if.c:343
 br_dev_delete+0x4e/0xe0 net/bridge/br_if.c:386
 br_net_exit_rtnl+0x92/0xf0 net/bridge/br.c:414
 ops_exit_rtnl_list net/core/net_namespace.c:181 [inline]
 ops_undo_list+0x1be/0x420 net/core/net_namespace.c:248
 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 0xffffffff86c6a680 of 16 bytes by task 31091 on cpu 0:
 desc_read kernel/printk/printk_ringbuffer.c:496 [inline]
 desc_read_finalized_seq kernel/printk/printk_ringbuffer.c:1931 [inline]
 prb_read kernel/printk/printk_ringbuffer.c:1979 [inline]
 _prb_read_valid+0x1bc/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]
 con_install+0x2df/0x330 drivers/tty/vt/vt.c:3669
 tty_driver_install_tty drivers/tty/tty_io.c:1295 [inline]
 tty_init_dev+0x7c/0x320 drivers/tty/tty_io.c:1407
 tty_open_by_driver drivers/tty/tty_io.c:2073 [inline]
 tty_open+0x6c6/0xaf0 drivers/tty/tty_io.c:2120
 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

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 UID: 0 PID: 31091 Comm: syz.5.8455 Not tainted syzkaller #0 PREEMPT(full) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 02/12/2026
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