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BUG: KCSAN: data-race in serial8250_do_startup / serial8250_handle_irq

write to 0xffffffff88eb2ae6 of 1 bytes by task 11921 on cpu 1:
 serial8250_do_startup+0x165e/0x1eb0 drivers/tty/serial/8250/8250_port.c:2460
 serial8250_startup+0x41/0x50 drivers/tty/serial/8250/8250_port.c:2482
 uart_port_startup drivers/tty/serial/serial_core.c:324 [inline]
 uart_startup+0x468/0x8e0 drivers/tty/serial/serial_core.c:368
 uart_do_autoconfig drivers/tty/serial/serial_core.c:1185 [inline]
 uart_ioctl+0xc43/0xe40 drivers/tty/serial/serial_core.c:1588
 tty_ioctl+0x7db/0xb80 drivers/tty/tty_io.c:2792
 vfs_ioctl fs/ioctl.c:51 [inline]
 __do_sys_ioctl fs/ioctl.c:907 [inline]
 __se_sys_ioctl+0xce/0x140 fs/ioctl.c:893
 __x64_sys_ioctl+0x43/0x50 fs/ioctl.c:893
 x64_sys_call+0x19a8/0x2fb0 arch/x86/include/generated/asm/syscalls_64.h:17
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xd2/0x200 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

read to 0xffffffff88eb2ae6 of 1 bytes by interrupt on cpu 0:
 serial8250_handle_irq+0x3f9/0x660 drivers/tty/serial/8250/8250_port.c:1944
 serial8250_default_handle_irq+0x8e/0x120 drivers/tty/serial/8250/8250_port.c:1966
 serial8250_interrupt+0x60/0x110 drivers/tty/serial/8250/8250_core.c:86
 __handle_irq_event_percpu+0x93/0x440 kernel/irq/handle.c:158
 handle_irq_event_percpu kernel/irq/handle.c:193 [inline]
 handle_irq_event+0x64/0xf0 kernel/irq/handle.c:210
 handle_edge_irq+0x188/0x4f0 kernel/irq/chip.c:797
 generic_handle_irq_desc include/linux/irqdesc.h:173 [inline]
 handle_irq arch/x86/kernel/irq.c:254 [inline]
 call_irq_handler arch/x86/kernel/irq.c:266 [inline]
 __common_interrupt+0x63/0x100 arch/x86/kernel/irq.c:292
 common_interrupt+0x3e/0x90 arch/x86/kernel/irq.c:285
 asm_common_interrupt+0x26/0x40 arch/x86/include/asm/idtentry.h:693

value changed: 0x00 -> 0x05

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 UID: 0 PID: 11912 Comm: syz.8.25279 Tainted: G        W           6.16.0-rc5-syzkaller-00053-g8c2e52ebbe88 #0 PREEMPT(voluntary) 
Tainted: [W]=WARN
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/07/2025
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