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BUG: KCSAN: data-race in rtc_dev_poll / rtc_pie_update_irq

read-write to 0xffff88810328db80 of 8 bytes by interrupt on cpu 0:
 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+0x20c/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:1038 [inline]
 __sysvec_apic_timer_interrupt+0x5c/0x1d0 arch/x86/kernel/apic/apic.c:1055
 instr_sysvec_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1049 [inline]
 sysvec_apic_timer_interrupt+0x6f/0x80 arch/x86/kernel/apic/apic.c:1049
 asm_sysvec_apic_timer_interrupt+0x1a/0x20 arch/x86/include/asm/idtentry.h:702
 rcu_read_unlock_sched include/linux/rcupdate.h:955 [inline]
 pfn_valid include/linux/mmzone.h:2127 [inline]
 mark_nosave_pages kernel/power/snapshot.c:1098 [inline]
 create_basic_memory_bitmaps+0x4b9/0x5b0 kernel/power/snapshot.c:1146
 snapshot_open+0x1b4/0x270 kernel/power/user.c:89
 misc_open+0x1d3/0x200 drivers/char/misc.c:179
 chrdev_open+0x2e8/0x3a0 fs/char_dev.c:414
 do_dentry_open+0x646/0xa20 fs/open.c:956
 vfs_open+0x37/0x1e0 fs/open.c:1086
 do_open fs/namei.c:3880 [inline]
 path_openat+0x1c5e/0x2170 fs/namei.c:4039
 do_filp_open+0x109/0x230 fs/namei.c:4066
 do_sys_openat2+0xa6/0x110 fs/open.c:1429
 do_sys_open fs/open.c:1444 [inline]
 __do_sys_openat fs/open.c:1460 [inline]
 __se_sys_openat fs/open.c:1455 [inline]
 __x64_sys_openat+0xf2/0x120 fs/open.c:1455
 x64_sys_call+0x1af/0x2fb0 arch/x86/include/generated/asm/syscalls_64.h:258
 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 0xffff88810328db80 of 8 bytes by task 12746 on cpu 1:
 rtc_dev_poll+0x78/0xb0 drivers/rtc/dev.c:198
 vfs_poll include/linux/poll.h:82 [inline]
 __io_arm_poll_handler+0x1eb/0xb70 io_uring/poll.c:583
 io_arm_poll_handler+0x427/0x5b0 io_uring/poll.c:708
 io_queue_async+0x86/0x440 io_uring/io_uring.c:1953
 io_queue_sqe io_uring/io_uring.c:1982 [inline]
 io_req_task_submit+0xbb/0xc0 io_uring/io_uring.c:1375
 io_handle_tw_list+0x18d/0x1c0 io_uring/io_uring.c:1062
 tctx_task_work_run+0x6d/0x1a0 io_uring/io_uring.c:1127
 tctx_task_work+0x3f/0x80 io_uring/io_uring.c:1145
 task_work_run+0x12e/0x1a0 kernel/task_work.c:227
 get_signal+0xe13/0xf70 kernel/signal.c:2807
 arch_do_signal_or_restart+0x97/0x480 arch/x86/kernel/signal.c:337
 exit_to_user_mode_loop kernel/entry/common.c:111 [inline]
 exit_to_user_mode_prepare include/linux/entry-common.h:329 [inline]
 __syscall_exit_to_user_mode_work kernel/entry/common.c:207 [inline]
 syscall_exit_to_user_mode+0x68/0xb0 kernel/entry/common.c:218
 do_syscall_64+0xdd/0x1a0 arch/x86/entry/syscall_64.c:100
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

value changed: 0x00000000000021c0 -> 0x00000000000022c0

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 UID: 0 PID: 12746 Comm: syz.8.4011 Not tainted 6.15.0-rc4-syzkaller #0 PREEMPT(voluntary) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 02/12/2025
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