[moderation] [kernel?] KCSAN: data-race in print_cpu / tick_nohz_idle_stop_tick

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: 76eeb9b8de98 Linux 6.17-rc5
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=13da9562580000
kernel config: https://syzkaller.appspot.com/x/.config?x=6e0c213d0735f5dd
dashboard link: https://syzkaller.appspot.com/bug?extid=1810c74ddb4c43db6bdc
compiler: Debian clang version 20.1.8 (++20250708063551+0c9f909b7976-1~exp1~20250708183702.136), Debian LLD 20.1.8
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/f31a0e6f0a05/disk-76eeb9b8.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/1ed42a856be4/vmlinux-76eeb9b8.xz
kernel image: https://storage.googleapis.com/syzbot-assets/eeeecc65c274/bzImage-76eeb9b8.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+1810c7...@syzkaller.appspotmail.com

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

read-write to 0xffff888237d1b868 of 8 bytes by task 0 on cpu 1:
tick_nohz_idle_stop_tick+0x145/0x790 kernel/time/tick-sched.c:1222
cpuidle_idle_call kernel/sched/idle.c:188 [inline]
do_idle+0xc6/0x240 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 0xffff888237d1b868 of 8 bytes by task 22203 on cpu 0:
print_cpu+0x4b0/0x680 kernel/time/timer_list.c:160
timer_list_show+0x107/0x170 kernel/time/timer_list.c:295
seq_read_iter+0x316/0x940 fs/seq_file.c:230
proc_reg_read_iter+0x110/0x180 fs/proc/inode.c:299
copy_splice_read+0x43f/0x660 fs/splice.c:363
do_splice_read fs/splice.c:982 [inline]
splice_direct_to_actor+0x26c/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+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: 0x00000000000d9471 -> 0x00000000000d9472

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 UID: 0 PID: 22203 Comm: syz.2.15300 Tainted: G W syzkaller #0 PREEMPT(voluntary)
Tainted: [W]=WARN
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.