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BUG: KCSAN: data-race in desc_read_finalized_seq / prb_reserve

write to 0xffffffff8669b2b0 of 8 bytes by task 29 on cpu 1:
 prb_reserve+0x740/0xb60
 vprintk_store+0x558/0x870 kernel/printk/printk.c:2326
 vprintk_emit+0x168/0x690 kernel/printk/printk.c:2408
 vprintk_deferred kernel/printk/printk.c:4571 [inline]
 _printk_deferred+0x83/0xb0 kernel/printk/printk.c:4580
 ___ratelimit+0x294/0x2b0 lib/ratelimit.c:56
 __printk_ratelimit+0x1c/0x30 kernel/printk/printk.c:4596
 kauditd_printk_skb kernel/audit.c:545 [inline]
 kauditd_hold_skb+0x61/0x1b0 kernel/audit.c:581
 kauditd_send_queue+0x288/0x2e0 kernel/audit.c:766
 kauditd_thread+0x42a/0x650 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 0xffffffff8669b2b0 of 8 bytes by task 21044 on cpu 0:
 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
 printk_get_next_message+0xd8/0x530 kernel/printk/printk.c:2989
 console_emit_next_record kernel/printk/printk.c:3076 [inline]
 console_flush_all+0x2a7/0x790 kernel/printk/printk.c:3210
 __console_flush_and_unlock kernel/printk/printk.c:3269 [inline]
 console_unlock+0xb6/0x340 kernel/printk/printk.c:3309
 do_con_write+0x2582/0x25f0
 con_put_char+0x39/0x60 drivers/tty/vt/vt.c:3440
 tty_put_char+0x67/0xc0 drivers/tty/tty_io.c:3166
 do_output_char+0x4de/0x500 drivers/tty/n_tty.c:469
 process_output drivers/tty/n_tty.c:494 [inline]
 n_tty_write+0x8c6/0xb80 drivers/tty/n_tty.c:2400
 iterate_tty_write drivers/tty/tty_io.c:1015 [inline]
 file_tty_write+0x37a/0x680 drivers/tty/tty_io.c:1090
 tty_write+0x28/0x30 drivers/tty/tty_io.c:1111
 new_sync_write fs/read_write.c:586 [inline]
 vfs_write+0x77b/0x920 fs/read_write.c:679
 ksys_write+0xe8/0x1b0 fs/read_write.c:731
 __do_sys_write fs/read_write.c:742 [inline]
 __se_sys_write fs/read_write.c:739 [inline]
 __x64_sys_write+0x42/0x50 fs/read_write.c:739
 x64_sys_call+0x287e/0x2dc0 arch/x86/include/generated/asm/syscalls_64.h:2
 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: 0x000000000000210c -> 0x000000000000410c

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 UID: 0 PID: 21044 Comm: syz.1.5898 Not tainted 6.14.0-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 02/12/2025
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