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BUG: KCSAN: data-race in desc_read_finalized_seq / prb_reserve

write to 0xffffffff866ca310 of 8 bytes by task 29 on cpu 0:
 prb_reserve+0x740/0xb60
 vprintk_store+0x558/0x870 kernel/printk/printk.c:2326
 vprintk_emit+0x168/0x690 kernel/printk/printk.c:2408
 vprintk_default+0x26/0x30 kernel/printk/printk.c:2447
 vprintk+0x1d/0x30 kernel/printk/printk_safe.c:82
 _printk+0x7a/0xa0 kernel/printk/printk.c:2457
 kauditd_printk_skb kernel/audit.c:546 [inline]
 kauditd_hold_skb+0x1a3/0x1b0 kernel/audit.c:581
 kauditd_send_queue+0x288/0x2e0 kernel/audit.c:766
 kauditd_thread+0x42a/0x640 kernel/audit.c:890
 kthread+0x4ae/0x520 kernel/kthread.c:464
 ret_from_fork+0x4b/0x60 arch/x86/kernel/process.c:148
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:244

read to 0xffffffff866ca310 of 8 bytes by task 28347 on cpu 1:
 desc_read kernel/printk/printk_ringbuffer.c:486 [inline]
 desc_read_finalized_seq+0x157/0x280 kernel/printk/printk_ringbuffer.c:1874
 prb_read kernel/printk/printk_ringbuffer.c:1922 [inline]
 _prb_read_valid+0x140/0x6c0 kernel/printk/printk_ringbuffer.c:2113
 prb_read_valid+0x3d/0x60 kernel/printk/printk_ringbuffer.c:2182
 __console_flush_and_unlock kernel/printk/printk.c:3286 [inline]
 console_unlock+0x180/0x340 kernel/printk/printk.c:3307
 con_install+0x28d/0x2d0 drivers/tty/vt/vt.c:3545
 tty_driver_install_tty drivers/tty/tty_io.c:1304 [inline]
 tty_init_dev+0x7b/0x320 drivers/tty/tty_io.c:1416
 tty_open_by_driver drivers/tty/tty_io.c:2082 [inline]
 tty_open+0x6c7/0xb00 drivers/tty/tty_io.c:2129
 chrdev_open+0x2f9/0x370 fs/char_dev.c:414
 do_dentry_open+0x621/0xa20 fs/open.c:956
 vfs_open+0x38/0x1e0 fs/open.c:1086
 do_open fs/namei.c:3845 [inline]
 path_openat+0x1afe/0x1fe0 fs/namei.c:4004
 do_filp_open+0x10a/0x230 fs/namei.c:4031
 do_sys_openat2+0xa5/0x110 fs/open.c:1429
 do_sys_open fs/open.c:1444 [inline]
 __do_sys_openat fs/open.c:1460 [inline]
 __se_sys_openat fs/open.c:1455 [inline]
 __x64_sys_openat+0xf3/0x120 fs/open.c:1455
 x64_sys_call+0x1ac/0x2e10 arch/x86/include/generated/asm/syscalls_64.h:258
 do_syscall_x64 arch/x86/entry/common.c:52 [inline]
 do_syscall_64+0xc9/0x1c0 arch/x86/entry/common.c:83
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

value changed: 0x0000000000002998 -> 0x0000000000004998

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 UID: 0 PID: 28347 Comm: syz.2.20684 Not tainted 6.14.0-syzkaller-00685-g3ba7dfb8da62 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 02/12/2025
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