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BUG: KCSAN: data-race in _prb_read_valid / prb_reserve

write to 0xffffffff86eb3900 of 88 bytes by task 29 on cpu 0:
 prb_reserve+0x6fb/0xaf0 kernel/printk/printk_ringbuffer.c:1691
 vprintk_store+0x54e/0x910 kernel/printk/printk.c:2354
 vprintk_emit+0x1a4/0x580 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
 kauditd_printk_skb kernel/audit.c:588 [inline]
 kauditd_hold_skb+0x1b1/0x1c0 kernel/audit.c:623
 kauditd_send_queue+0x275/0x2d0 kernel/audit.c:808
 kauditd_thread+0x439/0x660 kernel/audit.c:932
 kthread+0x223/0x270 kernel/kthread.c:436
 ret_from_fork+0x146/0x330 arch/x86/kernel/process.c:158
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245

read to 0xffffffff86eb3900 of 8 bytes by task 28004 on cpu 1:
 desc_read kernel/printk/printk_ringbuffer.c:499 [inline]
 prb_first_seq kernel/printk/printk_ringbuffer.c:2014 [inline]
 _prb_read_valid+0x636/0x8f0 kernel/printk/printk_ringbuffer.c:2171
 prb_first_valid_seq+0x35/0x70 kernel/printk/printk_ringbuffer.c:2299
 devkmsg_open+0x174/0x1b0 kernel/printk/printk.c:945
 memory_open+0xfa/0x120 mm/char-mem.c:736
 chrdev_open+0x2eb/0x3a0 fs/char_dev.c:413
 do_dentry_open+0x496/0xa40 fs/open.c:1000
 vfs_open_consume+0x46/0x1f0 fs/open.c:1131
 do_open fs/namei.c:4845 [inline]
 path_openat+0xc16/0x11c0 fs/namei.c:5010
 do_file_open+0x16c/0x290 fs/namei.c:5039
 do_sys_openat2+0xa1/0x140 fs/open.c:1442
 do_sys_open fs/open.c:1448 [inline]
 __do_sys_openat fs/open.c:1464 [inline]
 __se_sys_openat fs/open.c:1459 [inline]
 __x64_sys_openat+0xf2/0x120 fs/open.c:1459
 x64_sys_call+0x1f72/0x2550 arch/x86/include/generated/asm/syscalls_64.h:258
 do_syscall_x64 arch/x86/entry/syscall_64.c:61 [inline]
 do_syscall_64+0x112/0x360 arch/x86/entry/syscall_64.c:84
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

value changed: 0x00000000000025ce -> 0x00000000000045ce

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 UID: 0 PID: 28004 Comm: syz.2.3677 Not tainted syzkaller #0 PREEMPT(lazy) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 09/16/2026
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