syzbot

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BUG: KCSAN: data-race in hrtimer_interrupt / print_cpu

read-write to 0xffff888237c1b254 of 4 bytes by interrupt on cpu 0:
 hrtimer_interrupt+0x70/0x460 kernel/time/hrtimer.c:1865
 local_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1039 [inline]
 __sysvec_apic_timer_interrupt+0x5f/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
 __tlb_remove_folio_pages_size mm/mmu_gather.c:-1 [inline]
 __tlb_remove_folio_pages+0x7b/0x220 mm/mmu_gather.c:208
 zap_present_folio_ptes mm/memory.c:1534 [inline]
 zap_present_ptes mm/memory.c:1590 [inline]
 do_zap_pte_range mm/memory.c:1691 [inline]
 zap_pte_range mm/memory.c:1735 [inline]
 zap_pmd_range mm/memory.c:1827 [inline]
 zap_pud_range mm/memory.c:1856 [inline]
 zap_p4d_range mm/memory.c:1877 [inline]
 unmap_page_range+0x158a/0x2740 mm/memory.c:1898
 unmap_single_vma mm/memory.c:1941 [inline]
 unmap_vmas+0x23d/0x3a0 mm/memory.c:1985
 exit_mmap+0x1b0/0x6c0 mm/mmap.c:1284
 __mmput+0x28/0x1c0 kernel/fork.c:1121
 mmput+0x40/0x50 kernel/fork.c:1144
 exit_mm+0xe4/0x190 kernel/exit.c:581
 do_exit+0x417/0x1590 kernel/exit.c:952
 do_group_exit+0xff/0x140 kernel/exit.c:1105
 get_signal+0xe59/0xf70 kernel/signal.c:3034
 arch_do_signal_or_restart+0x96/0x480 arch/x86/kernel/signal.c:337
 exit_to_user_mode_loop+0x7a/0x100 kernel/entry/common.c:111
 exit_to_user_mode_prepare include/linux/entry-common.h:330 [inline]
 syscall_exit_to_user_mode_work include/linux/entry-common.h:414 [inline]
 syscall_exit_to_user_mode include/linux/entry-common.h:449 [inline]
 do_syscall_64+0x1d6/0x200 arch/x86/entry/syscall_64.c:100
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

read to 0xffff888237c1b254 of 4 bytes by task 5505 on cpu 1:
 print_cpu+0x359/0x680 kernel/time/timer_list.c:135
 timer_list_show+0x107/0x170 kernel/time/timer_list.c:295
 seq_read_iter+0x62a/0x940 fs/seq_file.c:272
 proc_reg_read_iter+0x110/0x180 fs/proc/inode.c:299
 copy_splice_read+0x3c4/0x5f0 fs/splice.c:363
 do_splice_read fs/splice.c:979 [inline]
 splice_direct_to_actor+0x26f/0x680 fs/splice.c:1083
 do_splice_direct_actor fs/splice.c:1201 [inline]
 do_splice_direct+0xda/0x150 fs/splice.c:1227
 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+0xb39/0x2fb0 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: 0x0004e7bd -> 0x0004e7be

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 UID: 0 PID: 5505 Comm: syz.1.672 Tainted: G        W           6.16.0-rc4-syzkaller-00013-g66701750d556 #0 PREEMPT(voluntary) 
Tainted: [W]=WARN
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/07/2025
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