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BUG: KCSAN: data-race in rtc_dev_poll / rtc_pie_update_irq

read-write to 0xffff888103951388 of 8 bytes by interrupt on cpu 0:
 rtc_handle_legacy_irq drivers/rtc/interface.c:651 [inline]
 rtc_pie_update_irq+0x7b/0xd0 drivers/rtc/interface.c:699
 __run_hrtimer kernel/time/hrtimer.c:1785 [inline]
 __hrtimer_run_queues+0x207/0x4c0 kernel/time/hrtimer.c:1849
 hrtimer_interrupt+0x269/0x810 kernel/time/hrtimer.c:1911
 local_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1045 [inline]
 __sysvec_apic_timer_interrupt+0x5f/0x1d0 arch/x86/kernel/apic/apic.c:1062
 instr_sysvec_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1056 [inline]
 sysvec_apic_timer_interrupt+0x32/0x80 arch/x86/kernel/apic/apic.c:1056
 asm_sysvec_apic_timer_interrupt+0x1a/0x20 arch/x86/include/asm/idtentry.h:697

read to 0xffff888103951388 of 8 bytes by task 16444 on cpu 1:
 rtc_dev_poll+0x78/0xb0 drivers/rtc/dev.c:198
 vfs_poll include/linux/poll.h:82 [inline]
 io_file_supports_nowait io_uring/rw.c:47 [inline]
 __io_read+0x312/0xc50 io_uring/rw.c:936
 io_read+0x4a/0x190 io_uring/rw.c:1030
 __io_issue_sqe+0xfd/0x2d0 io_uring/io_uring.c:1384
 io_issue_sqe+0x208/0xbf0 io_uring/io_uring.c:1407
 io_queue_sqe io_uring/io_uring.c:1634 [inline]
 io_req_task_submit+0x46/0xa0 io_uring/io_uring.c:1044
 io_handle_tw_list+0x1f5/0x230 io_uring/tw.c:72
 tctx_task_work_run+0x42/0x160 io_uring/tw.c:132
 tctx_task_work+0x3f/0x80 io_uring/tw.c:150
 task_work_run+0x130/0x1a0 kernel/task_work.c:233
 get_signal+0xe09/0xf60 kernel/signal.c:2807
 arch_do_signal_or_restart+0x96/0x450 arch/x86/kernel/signal.c:337
 __exit_to_user_mode_loop kernel/entry/common.c:64 [inline]
 exit_to_user_mode_loop+0x6a/0x6f0 kernel/entry/common.c:98
 __exit_to_user_mode_prepare include/linux/irq-entry-common.h:226 [inline]
 syscall_exit_to_user_mode_prepare include/linux/irq-entry-common.h:256 [inline]
 syscall_exit_to_user_mode include/linux/entry-common.h:325 [inline]
 do_syscall_64+0x249/0x370 arch/x86/entry/syscall_64.c:100
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

value changed: 0x00000000000183c0 -> 0x00000000000184c0

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 UID: 0 PID: 16444 Comm: syz.7.3678 Tainted: G        W           syzkaller #0 PREEMPT(full) 
Tainted: [W]=WARN
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/24/2026
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