[moderation] [kernel?] KCSAN: data-race in print_cpu / tick_nohz_stop_idle (6)

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: f2d282e1dfb3 Merge tag 'bitmap-for-6.17' of https://github..
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=128042a2580000
kernel config: https://syzkaller.appspot.com/x/.config?x=6deb4b0193f5469d
dashboard link: https://syzkaller.appspot.com/bug?extid=bfeb2dcce64406abb5c2
compiler: Debian clang version 20.1.7 (++20250616065708+6146a88f6049-1~exp1~20250616065826.132), Debian LLD 20.1.7
CC: [anna-...@linutronix.de fred...@kernel.org linux-...@vger.kernel.org mi...@kernel.org tg...@linutronix.de]

Unfortunately, I don't have any reproducer for this issue yet.

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/d8649577ee80/disk-f2d282e1.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/f9ecd82084aa/vmlinux-f2d282e1.xz
kernel image: https://storage.googleapis.com/syzbot-assets/aa1864575896/bzImage-f2d282e1.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+bfeb2d...@syzkaller.appspotmail.com

==================================================================
BUG: KCSAN: data-race in print_cpu / tick_nohz_stop_idle

write to 0xffff888237d1b838 of 8 bytes by interrupt on cpu 1:
tick_nohz_stop_idle+0xbf/0x120 kernel/time/tick-sched.c:738
tick_nohz_irq_enter kernel/time/tick-sched.c:1528 [inline]
tick_irq_enter+0xa1/0x150 kernel/time/tick-sched.c:1554
instr_sysvec_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1050 [inline]
sysvec_apic_timer_interrupt+0x67/0x80 arch/x86/kernel/apic/apic.c:1050
asm_sysvec_apic_timer_interrupt+0x1a/0x20 arch/x86/include/asm/idtentry.h:702
native_safe_halt arch/x86/include/asm/irqflags.h:48 [inline]
pv_native_safe_halt+0x13/0x20 arch/x86/kernel/paravirt.c:81
arch_safe_halt arch/x86/include/asm/paravirt.h:107 [inline]
default_idle+0x13/0x20 arch/x86/kernel/process.c:757
default_idle_call+0x3d/0x70 kernel/sched/idle.c:122
cpuidle_idle_call kernel/sched/idle.c:190 [inline]
do_idle+0xcb/0x240 kernel/sched/idle.c:330
cpu_startup_entry+0x25/0x30 kernel/sched/idle.c:428
start_secondary+0x95/0xa0 arch/x86/kernel/smpboot.c:315
common_startup_64+0x13e/0x147

read to 0xffff888237d1b838 of 8 bytes by task 6552 on cpu 0:
print_cpu+0x502/0x680 kernel/time/timer_list.c:162
timer_list_show+0x107/0x170 kernel/time/timer_list.c:295
seq_read_iter+0x627/0x940 fs/seq_file.c:272
proc_reg_read_iter+0x10d/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+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

value changed: 0x000000188cb583c9 -> 0x000000188cb6ebae

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 UID: 0 PID: 6552 Comm: syz.4.949 Not tainted 6.16.0-syzkaller-10355-gf2d282e1dfb3 #0 PREEMPT(voluntary)
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/12/2025
==================================================================


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[syzbot]

Auto-closing this bug as obsolete.
Crashes did not happen for a while, no reproducer and no activity.