syzbot

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BUG: KCSAN: data-race in hrtimer_reprogram / print_cpu

write to 0xffff888237c1b2a0 of 8 bytes by task 5020 on cpu 0:
 __hrtimer_reprogram kernel/time/hrtimer.c:656 [inline]
 hrtimer_reprogram+0x1a5/0x220 kernel/time/hrtimer.c:861
 hrtimer_start_range_ns+0x6b1/0x740 kernel/time/hrtimer.c:1323
 hrtimer_start_expires include/linux/hrtimer.h:273 [inline]
 hrtimer_restart include/linux/hrtimer.h:281 [inline]
 common_hrtimer_rearm+0x85/0x90 kernel/time/posix-timers.c:303
 __posixtimer_deliver_signal kernel/time/posix-timers.c:321 [inline]
 posixtimer_deliver_signal+0x120/0x320 kernel/time/posix-timers.c:347
 dequeue_signal+0x2cf/0x3b0 kernel/signal.c:660
 get_signal+0x376/0xf70 kernel/signal.c:2914
 arch_do_signal_or_restart+0x96/0x440 arch/x86/kernel/signal.c:337
 exit_to_user_mode_loop+0x77/0x110 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

read to 0xffff888237c1b2a0 of 8 bytes by task 5016 on cpu 1:
 print_cpu+0x2ea/0x660 kernel/time/timer_list.c:131
 timer_list_show+0x107/0x170 kernel/time/timer_list.c:293
 seq_read_iter+0x636/0x950 fs/seq_file.c:272
 proc_reg_read_iter+0x110/0x180 fs/proc/inode.c:299
 copy_splice_read+0x442/0x660 fs/splice.c:363
 do_splice_read fs/splice.c:982 [inline]
 splice_direct_to_actor+0x26f/0x680 fs/splice.c:1086
 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+0x2bb4/0x3000 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

value changed: 0x00000010651d79ad -> 0x00000010651019dc

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 UID: 0 PID: 5016 Comm: syz.4.578 Not tainted syzkaller #0 PREEMPT(voluntary) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/02/2025
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