[moderation] [kernel?] KCSAN: data-race in clockevents_program_event / print_tickdevice (14)

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: 27d128c1cff6 Merge tag 'trace-ring-buffer-v7.1-3' of git:/..
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=17738506580000
kernel config: https://syzkaller.appspot.com/x/.config?x=2e40c0f41e01837e
dashboard link: https://syzkaller.appspot.com/bug?extid=00e5a73d76c701febd2a
compiler: Debian clang version 21.1.8 (++20251221033036+2078da43e25a-1~exp1~20251221153213.50), Debian LLD 21.1.8
CC: [anna-...@linutronix.de fred...@kernel.org linux-...@vger.kernel.org tg...@kernel.org]

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

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/297d9521c6ba/disk-27d128c1.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/a67992be46b3/vmlinux-27d128c1.xz
kernel image: https://storage.googleapis.com/syzbot-assets/630edaa6f659/bzImage-27d128c1.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+00e5a7...@syzkaller.appspotmail.com

==================================================================
BUG: KCSAN: data-race in clockevents_program_event / print_tickdevice

write to 0xffff888237c17ba0 of 8 bytes by task 17100 on cpu 0:
clockevents_program_event+0x46/0x340 kernel/time/clockevents.c:347
tick_program_event+0x79/0xc0 kernel/time/tick-oneshot.c:48
hrtimer_rearm_event kernel/time/hrtimer.c:707 [inline]
hrtimer_rearm kernel/time/hrtimer.c:2039 [inline]
__hrtimer_rearm_deferred+0x571/0x670 kernel/time/hrtimer.c:2059
hrtimer_rearm_deferred_tif include/linux/hrtimer_rearm.h:53 [inline]
hrtimer_rearm_deferred include/linux/hrtimer_rearm.h:62 [inline]
irqentry_exit_to_kernel_mode_after_preempt include/linux/irq-entry-common.h:513 [inline]
irqentry_exit_to_kernel_mode include/linux/irq-entry-common.h:550 [inline]
irqentry_exit+0x527/0x5b0 kernel/entry/common.c:164
sysvec_apic_timer_interrupt+0x44/0x80 arch/x86/kernel/apic/apic.c:1061
asm_sysvec_apic_timer_interrupt+0x1a/0x20 arch/x86/include/asm/idtentry.h:697
finish_task_switch+0x132/0x320 kernel/sched/core.c:5244
context_switch kernel/sched/core.c:5390 [inline]
__schedule+0x936/0xd20 kernel/sched/core.c:7188
__schedule_loop kernel/sched/core.c:7267 [inline]
schedule+0x5e/0xd0 kernel/sched/core.c:7282
schedule_timeout+0x53/0x180 kernel/time/sleep_timeout.c:75
unix_wait_for_peer+0x135/0x1a0 net/unix/af_unix.c:1622
unix_dgram_sendmsg+0x8de/0x1050 net/unix/af_unix.c:2261
sock_sendmsg_nosec net/socket.c:787 [inline]
__sock_sendmsg net/socket.c:802 [inline]
____sys_sendmsg+0x563/0x5b0 net/socket.c:2698
___sys_sendmsg+0x195/0x1e0 net/socket.c:2752
__sys_sendmmsg+0x185/0x320 net/socket.c:2841
__do_sys_sendmmsg net/socket.c:2868 [inline]
__se_sys_sendmmsg net/socket.c:2865 [inline]
__x64_sys_sendmmsg+0x57/0x70 net/socket.c:2865
x64_sys_call+0x27aa/0x3020 arch/x86/include/generated/asm/syscalls_64.h:308
do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
do_syscall_64+0x12c/0x3b0 arch/x86/entry/syscall_64.c:94
entry_SYSCALL_64_after_hwframe+0x77/0x7f

read to 0xffff888237c17ba0 of 8 bytes by task 17098 on cpu 1:
print_tickdevice+0x142/0x340 kernel/time/timer_list.c:204
timer_list_show+0x6c/0x170 kernel/time/timer_list.c:296
seq_read_iter+0x636/0x940 fs/seq_file.c:273
proc_reg_read_iter+0x110/0x180 fs/proc/inode.c:299
copy_splice_read+0x471/0x6c0 fs/splice.c:362
do_splice_read fs/splice.c:980 [inline]
splice_direct_to_actor+0x26e/0x670 fs/splice.c:1084
do_splice_direct_actor fs/splice.c:1202 [inline]
do_splice_direct+0x119/0x1a0 fs/splice.c:1228
do_sendfile+0x382/0x650 fs/read_write.c:1372
__do_sys_sendfile64 fs/read_write.c:1433 [inline]
__se_sys_sendfile64 fs/read_write.c:1419 [inline]
__x64_sys_sendfile64+0x105/0x150 fs/read_write.c:1419
x64_sys_call+0x2dc4/0x3020 arch/x86/include/generated/asm/syscalls_64.h:41
do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
do_syscall_64+0x12c/0x3b0 arch/x86/entry/syscall_64.c:94
entry_SYSCALL_64_after_hwframe+0x77/0x7f

value changed: 0x7fffffffffffffff -> 0x0000006fa15375aa

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 UID: 0 PID: 17098 Comm: syz.4.3227 Tainted: G W syzkaller #0 PREEMPT(full)
Tainted: [W]=WARN
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 04/18/2026
==================================================================


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