[moderation] [kernel?] KCSAN: data-race in hrtimer_reprogram / print_cpu (13)

Hello,

syzbot found the following issue on:

HEAD commit: 1a9239bb4253 Merge tag 'net-next-6.15' of git://git.kernel..
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=13cf1bb0580000
kernel config: https://syzkaller.appspot.com/x/.config?x=6c26a48759893590
dashboard link: https://syzkaller.appspot.com/bug?extid=bb9993ac9f08ac26b880
compiler: Debian clang version 15.0.6, GNU ld (GNU Binutils for Debian) 2.40
CC: [[email protected] [email protected] [email protected] [email protected]]

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

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/8ba793bb0ba5/disk-1a9239bb.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/90404ba93367/vmlinux-1a9239bb.xz
kernel image: https://storage.googleapis.com/syzbot-assets/d299b74bc9c3/bzImage-1a9239bb.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: [email protected]

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

write to 0xffff888237c1ae20 of 8 bytes by task 8195 on cpu 0:
__hrtimer_reprogram kernel/time/hrtimer.c:665 [inline]
hrtimer_reprogram+0x1a2/0x220 kernel/time/hrtimer.c:870
hrtimer_start_range_ns+0x6a2/0x730 kernel/time/hrtimer.c:1334
hrtimer_start include/linux/hrtimer.h:265 [inline]
perf_swevent_start_hrtimer kernel/events/core.c:11659 [inline]
cpu_clock_event_start kernel/events/core.c:11716 [inline]
cpu_clock_event_add+0x10e/0x130 kernel/events/core.c:11728
event_sched_in+0x4a8/0x710 kernel/events/core.c:2663
group_sched_in kernel/events/core.c:2696 [inline]
merge_sched_in kernel/events/core.c:3930 [inline]
visit_groups_merge+0xc10/0x1d10 kernel/events/core.c:3875
pmu_groups_sched_in kernel/events/core.c:3961 [inline]
__pmu_ctx_sched_in+0xcd/0xf0 kernel/events/core.c:3973
ctx_sched_in+0x361/0x3b0 kernel/events/core.c:4024
perf_event_sched_in kernel/events/core.c:2794 [inline]
perf_event_context_sched_in kernel/events/core.c:4071 [inline]
__perf_event_task_sched_in+0x59e/0xa80 kernel/events/core.c:4100
perf_event_task_sched_in include/linux/perf_event.h:1573 [inline]
finish_task_switch+0x218/0x2b0 kernel/sched/core.c:5235
context_switch kernel/sched/core.c:5369 [inline]
__schedule+0x82d/0xae0 kernel/sched/core.c:6747
__schedule_loop kernel/sched/core.c:6824 [inline]
schedule+0x5f/0xd0 kernel/sched/core.c:6839
exit_to_user_mode_loop kernel/entry/common.c:102 [inline]
exit_to_user_mode_prepare include/linux/entry-common.h:329 [inline]
__syscall_exit_to_user_mode_work kernel/entry/common.c:207 [inline]
syscall_exit_to_user_mode+0x42/0x120 kernel/entry/common.c:218
do_syscall_64+0xd6/0x1c0 arch/x86/entry/syscall_64.c:100
entry_SYSCALL_64_after_hwframe+0x77/0x7f

read to 0xffff888237c1ae20 of 8 bytes by task 8184 on cpu 1:
print_cpu+0x307/0x680 kernel/time/timer_list.c:133
timer_list_show+0x115/0x180 kernel/time/timer_list.c:295
seq_read_iter+0x661/0x970 fs/seq_file.c:272
proc_reg_read_iter+0x118/0x190 fs/proc/inode.c:299
copy_splice_read+0x390/0x5d0 fs/splice.c:363
do_splice_read fs/splice.c:979 [inline]
splice_direct_to_actor+0x26c/0x680 fs/splice.c:1083
do_splice_direct_actor fs/splice.c:1201 [inline]
do_splice_direct+0xd9/0x150 fs/splice.c:1227
do_sendfile+0x40a/0x690 fs/read_write.c:1368
__do_sys_sendfile64 fs/read_write.c:1429 [inline]
__se_sys_sendfile64 fs/read_write.c:1415 [inline]
__x64_sys_sendfile64+0x113/0x160 fs/read_write.c:1415
x64_sys_call+0xfc3/0x2e10 arch/x86/include/generated/asm/syscalls_64.h:41
do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
do_syscall_64+0xc9/0x1c0 arch/x86/entry/syscall_64.c:94
entry_SYSCALL_64_after_hwframe+0x77/0x7f

value changed: 0x000000247ebfffa5 -> 0x7fffffffffffffff

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 UID: 0 PID: 8184 Comm: syz.4.1703 Not tainted 6.14.0-syzkaller-05877-g1a9239bb4253 #0 PREEMPT(voluntary)
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 02/12/2025
==================================================================


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