serio: Serial port ptm0
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BUG: KCSAN: data-race in _prb_read_valid / prb_reserve

write to 0xffffffff868e7170 of 88 bytes by task 3309 on cpu 1:
 prb_reserve+0x696/0xaf0 kernel/printk/printk_ringbuffer.c:1635
 vprintk_store+0x56d/0x860 kernel/printk/printk.c:2326
 vprintk_emit+0x178/0x650 kernel/printk/printk.c:2426
 devkmsg_emit+0x7f/0xb0 kernel/printk/printk.c:755
 devkmsg_write+0x1e3/0x2b0 kernel/printk/printk.c:818
 do_iter_readv_writev+0x41e/0x4c0 fs/read_write.c:-1
 vfs_writev+0x2c9/0x870 fs/read_write.c:1055
 do_writev+0xe7/0x210 fs/read_write.c:1101
 __do_sys_writev fs/read_write.c:1169 [inline]
 __se_sys_writev fs/read_write.c:1166 [inline]
 __x64_sys_writev+0x45/0x50 fs/read_write.c:1166
 x64_sys_call+0x2006/0x2fb0 arch/x86/include/generated/asm/syscalls_64.h:21
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xd0/0x1a0 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

read to 0xffffffff868e7170 of 8 bytes by task 21628 on cpu 0:
 desc_read kernel/printk/printk_ringbuffer.c:486 [inline]
 desc_read_finalized_seq kernel/printk/printk_ringbuffer.c:1874 [inline]
 prb_read kernel/printk/printk_ringbuffer.c:1922 [inline]
 _prb_read_valid+0x1c4/0x920 kernel/printk/printk_ringbuffer.c:2113
 prb_read_valid+0x3c/0x60 kernel/printk/printk_ringbuffer.c:2185
 __console_flush_and_unlock kernel/printk/printk.c:3304 [inline]
 console_unlock+0x164/0x330 kernel/printk/printk.c:3325
 vprintk_emit+0x388/0x650 kernel/printk/printk.c:2450
 vprintk_default+0x26/0x30 kernel/printk/printk.c:2465
 vprintk+0x1d/0x30 kernel/printk/printk_safe.c:82
 _printk+0x79/0xa0 kernel/printk/printk.c:2475
 serport_ldisc_read+0x1ed/0x300 drivers/input/serio/serport.c:177
 iterate_tty_read drivers/tty/tty_io.c:856 [inline]
 tty_read+0x151/0x470 drivers/tty/tty_io.c:931
 do_iter_readv_writev+0x41e/0x4c0 fs/read_write.c:-1
 vfs_readv+0x1e3/0x670 fs/read_write.c:1016
 do_readv+0xe7/0x210 fs/read_write.c:1078
 __do_sys_readv fs/read_write.c:1163 [inline]
 __se_sys_readv fs/read_write.c:1160 [inline]
 __x64_sys_readv+0x45/0x50 fs/read_write.c:1160
 x64_sys_call+0x29af/0x2fb0 arch/x86/include/generated/asm/syscalls_64.h:20
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xd0/0x1a0 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

value changed: 0x0000000000002e72 -> 0x0000000000004e72

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 UID: 0 PID: 21628 Comm: syz.0.5696 Not tainted 6.15.0-rc6-syzkaller-00047-ge9565e23cd89 #0 PREEMPT(voluntary) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 04/19/2025
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