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BUG: KCSAN: data-race in n_tty_poll / tty_set_termios

write to 0xffff8881194b2908 of 44 bytes by task 11799 on cpu 1:
 tty_set_termios+0xc0/0x910 drivers/tty/tty_ioctl.c:335
 set_termios+0x4a7/0x4f0 drivers/tty/tty_ioctl.c:512
 tty_mode_ioctl+0x37f/0x5b0 drivers/tty/tty_ioctl.c:-1
 n_tty_ioctl_helper+0x87/0x370 drivers/tty/tty_ioctl.c:982
 n_tty_ioctl+0x101/0x230 drivers/tty/n_tty.c:2496
 tty_ioctl+0x83e/0xb80 drivers/tty/tty_io.c:2801
 vfs_ioctl fs/ioctl.c:51 [inline]
 __do_sys_ioctl fs/ioctl.c:597 [inline]
 __se_sys_ioctl+0xce/0x140 fs/ioctl.c:583
 __x64_sys_ioctl+0x43/0x50 fs/ioctl.c:583
 x64_sys_call+0x1563/0x3020 arch/x86/include/generated/asm/syscalls_64.h:17
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0x12c/0x370 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

read to 0xffff8881194b2914 of 4 bytes by task 11796 on cpu 0:
 input_available_p drivers/tty/n_tty.c:1912 [inline]
 n_tty_poll+0x12e/0x450 drivers/tty/n_tty.c:2440
 tty_poll+0x79/0xf0 drivers/tty/tty_io.c:2199
 vfs_poll include/linux/poll.h:82 [inline]
 __io_arm_poll_handler+0x1ec/0xc30 io_uring/poll.c:586
 io_arm_apoll+0x2eb/0x430 io_uring/poll.c:694
 io_arm_poll_handler+0x12f/0x160 io_uring/poll.c:723
 io_queue_async+0x25d/0x320 io_uring/io_uring.c:1615
 io_queue_sqe io_uring/io_uring.c:1641 [inline]
 io_submit_sqe io_uring/io_uring.c:1920 [inline]
 io_submit_sqes+0xbe2/0x1230 io_uring/io_uring.c:2043
 __do_sys_io_uring_enter io_uring/io_uring.c:2604 [inline]
 __se_sys_io_uring_enter+0x1c9/0xf50 io_uring/io_uring.c:2539
 __x64_sys_io_uring_enter+0x78/0x90 io_uring/io_uring.c:2539
 x64_sys_call+0x1e16/0x3020 arch/x86/include/generated/asm/syscalls_64.h:427
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0x12c/0x370 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

value changed: 0x00008a3b -> 0x00000008

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 UID: 0 PID: 11796 Comm: syz.8.1039 Tainted: G        W           syzkaller #0 PREEMPT(full) 
Tainted: [W]=WARN
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 02/12/2026
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