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BUG: KCSAN: data-race in rtc_dev_poll / rtc_pie_update_irq

read-write to 0xffff888103561388 of 8 bytes by interrupt on cpu 1:
 rtc_handle_legacy_irq drivers/rtc/interface.c:624 [inline]
 rtc_pie_update_irq+0x93/0xf0 drivers/rtc/interface.c:672
 __run_hrtimer kernel/time/hrtimer.c:1761 [inline]
 __hrtimer_run_queues+0x20f/0x5a0 kernel/time/hrtimer.c:1825
 hrtimer_interrupt+0x21a/0x460 kernel/time/hrtimer.c:1887
 local_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1039 [inline]
 __sysvec_apic_timer_interrupt+0x5c/0x1d0 arch/x86/kernel/apic/apic.c:1056
 instr_sysvec_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1050 [inline]
 sysvec_apic_timer_interrupt+0x6f/0x80 arch/x86/kernel/apic/apic.c:1050
 asm_sysvec_apic_timer_interrupt+0x1a/0x20 arch/x86/include/asm/idtentry.h:702
 kcsan_setup_watchpoint+0x415/0x430 kernel/kcsan/core.c:705
 init_sync_kiocb include/linux/fs.h:2478 [inline]
 iter_file_splice_write+0x5e4/0xa60 fs/splice.c:736
 do_splice_from fs/splice.c:938 [inline]
 direct_splice_actor+0x156/0x2a0 fs/splice.c:1161
 splice_direct_to_actor+0x312/0x680 fs/splice.c:1105
 do_splice_direct_actor fs/splice.c:1204 [inline]
 do_splice_direct+0xda/0x150 fs/splice.c:1230
 do_sendfile+0x380/0x650 fs/read_write.c:1370
 __do_sys_sendfile64 fs/read_write.c:1431 [inline]
 __se_sys_sendfile64 fs/read_write.c:1417 [inline]
 __x64_sys_sendfile64+0x105/0x150 fs/read_write.c:1417
 x64_sys_call+0x2bb0/0x2ff0 arch/x86/include/generated/asm/syscalls_64.h:41
 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 0xffff888103561388 of 8 bytes by task 18054 on cpu 0:
 rtc_dev_poll+0x78/0xb0 drivers/rtc/dev.c:198
 vfs_poll include/linux/poll.h:82 [inline]
 __io_arm_poll_handler+0x1ee/0xb70 io_uring/poll.c:581
 io_poll_add+0x69/0xe0 io_uring/poll.c:901
 __io_issue_sqe+0xfb/0x2e0 io_uring/io_uring.c:1771
 io_issue_sqe+0x53/0x970 io_uring/io_uring.c:1794
 io_queue_sqe io_uring/io_uring.c:2023 [inline]
 io_req_task_submit+0xa1/0x100 io_uring/io_uring.c:1413
 io_poll_task_func+0x68b/0x970 io_uring/poll.c:-1
 io_handle_tw_list+0xcc/0x1c0 io_uring/io_uring.c:1098
 tctx_task_work_run+0x6d/0x1a0 io_uring/io_uring.c:1163
 tctx_task_work+0x3f/0x80 io_uring/io_uring.c:1181
 task_work_run+0x12e/0x1a0 kernel/task_work.c:227
 get_signal+0xe13/0xf70 kernel/signal.c:2807
 arch_do_signal_or_restart+0x96/0x480 arch/x86/kernel/signal.c:337
 exit_to_user_mode_loop+0x7a/0x100 kernel/entry/common.c:40
 exit_to_user_mode_prepare include/linux/irq-entry-common.h:225 [inline]
 syscall_exit_to_user_mode_work include/linux/entry-common.h:175 [inline]
 syscall_exit_to_user_mode include/linux/entry-common.h:210 [inline]
 do_syscall_64+0x1d6/0x200 arch/x86/entry/syscall_64.c:100
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

value changed: 0x0000000000020bc0 -> 0x0000000000020cc0

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 UID: 0 PID: 18054 Comm: syz.8.5793 Not tainted syzkaller #0 PREEMPT(voluntary) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 08/18/2025
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