[moderation] [kernel?] KCSAN: data-race in hrtimer_reprogram / print_cpu (14)

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: b19a97d57c15 Merge tag 'pull-fixes' of git://git.kernel.or..
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=112fe6f0580000
kernel config: https://syzkaller.appspot.com/x/.config?x=86a2212b48ce4ce2
dashboard link: https://syzkaller.appspot.com/bug?extid=3aa321f3515b213afed0
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 tg...@linutronix.de]

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

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/6a2a270d1f41/disk-b19a97d5.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/b818795c1f60/vmlinux-b19a97d5.xz
kernel image: https://storage.googleapis.com/syzbot-assets/f9a4b6ce3bf0/bzImage-b19a97d5.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+3aa321...@syzkaller.appspotmail.com

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

write to 0xffff888237c1b260 of 8 bytes by task 21809 on cpu 0:
__hrtimer_reprogram kernel/time/hrtimer.c:663 [inline]
hrtimer_reprogram+0x1a5/0x220 kernel/time/hrtimer.c:868
hrtimer_start_range_ns+0x6b2/0x740 kernel/time/hrtimer.c:1330
hrtimer_start_expires include/linux/hrtimer.h:277 [inline]
hrtimer_sleeper_start_expires kernel/time/hrtimer.c:2023 [inline]
do_nanosleep+0x79/0x330 kernel/time/hrtimer.c:2097
hrtimer_nanosleep+0xdd/0x280 kernel/time/hrtimer.c:2147
common_nsleep+0x62/0x80 kernel/time/posix-timers.c:1353
__do_sys_clock_nanosleep kernel/time/posix-timers.c:1399 [inline]
__se_sys_clock_nanosleep+0x21a/0x250 kernel/time/posix-timers.c:1376
__x64_sys_clock_nanosleep+0x55/0x70 kernel/time/posix-timers.c:1376
x64_sys_call+0x272d/0x2ff0 arch/x86/include/generated/asm/syscalls_64.h:231
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

read to 0xffff888237c1b260 of 8 bytes by task 21830 on cpu 1:
print_cpu+0x30b/0x680 kernel/time/timer_list.c:133
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+0x442/0x660 fs/splice.c:363
do_splice_read fs/splice.c:982 [inline]
splice_direct_to_actor+0x26f/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: 0x0000003ef421889f -> 0x0000003ef4214b44

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 UID: 0 PID: 21830 Comm: syz.6.3611 Not tainted syzkaller #0 PREEMPT(voluntary)
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/12/2025
==================================================================


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