[moderation] [kernel?] KCSAN: data-race in print_cpu / tick_nohz_stop_idle (4)

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: 850925a8133c Merge tag '9p-for-6.12-rc5' of https://github..
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=143bc940580000
kernel config: https://syzkaller.appspot.com/x/.config?x=1ac60661f96136b0
dashboard link: https://syzkaller.appspot.com/bug?extid=1eb61f33d06d2d8148fd
compiler: Debian clang version 15.0.6, GNU ld (GNU Binutils for Debian) 2.40
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/c69e3f89b64a/disk-850925a8.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/52afd4ba1fff/vmlinux-850925a8.xz
kernel image: https://storage.googleapis.com/syzbot-assets/7235f45548e2/bzImage-850925a8.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+1eb61f...@syzkaller.appspotmail.com

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

read-write to 0xffff888237d204b0 of 8 bytes by interrupt on cpu 1:
tick_sched_flag_clear kernel/time/tick-sched.c:201 [inline]
tick_nohz_stop_idle+0xd0/0x110 kernel/time/tick-sched.c:747
tick_nohz_irq_enter kernel/time/tick-sched.c:1533 [inline]
tick_irq_enter+0xa2/0x150 kernel/time/tick-sched.c:1559
instr_sysvec_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1049 [inline]
sysvec_apic_timer_interrupt+0x66/0x80 arch/x86/kernel/apic/apic.c:1049
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]
arch_safe_halt arch/x86/include/asm/irqflags.h:106 [inline]
acpi_safe_halt+0x21/0x30 drivers/acpi/processor_idle.c:111
acpi_idle_do_entry+0x1d/0x30 drivers/acpi/processor_idle.c:568
acpi_idle_enter+0x96/0xb0 drivers/acpi/processor_idle.c:702
cpuidle_enter_state+0xc5/0x260 drivers/cpuidle/cpuidle.c:264
cpuidle_enter+0x40/0x70 drivers/cpuidle/cpuidle.c:385
call_cpuidle kernel/sched/idle.c:155 [inline]
cpuidle_idle_call kernel/sched/idle.c:230 [inline]
do_idle+0x195/0x230 kernel/sched/idle.c:326
cpu_startup_entry+0x25/0x30 kernel/sched/idle.c:424
start_secondary+0x96/0xa0 arch/x86/kernel/smpboot.c:314
common_startup_64+0x12c/0x137

read to 0xffff888237d204b0 of 8 bytes by task 3583 on cpu 0:
print_cpu+0x3dd/0x670 kernel/time/timer_list.c:155
timer_list_show+0x115/0x180 kernel/time/timer_list.c:295
seq_read_iter+0x655/0x930 fs/seq_file.c:272
proc_reg_read_iter+0x118/0x190 fs/proc/inode.c:299
copy_splice_read+0x3a0/0x5d0 fs/splice.c:365
do_splice_read fs/splice.c:985 [inline]
splice_direct_to_actor+0x269/0x670 fs/splice.c:1089
do_splice_direct_actor fs/splice.c:1207 [inline]
do_splice_direct+0xd7/0x150 fs/splice.c:1233
do_sendfile+0x39b/0x970 fs/read_write.c:1388
__do_sys_sendfile64 fs/read_write.c:1455 [inline]
__se_sys_sendfile64 fs/read_write.c:1441 [inline]
__x64_sys_sendfile64+0x110/0x150 fs/read_write.c:1441
x64_sys_call+0xed5/0x2d60 arch/x86/include/generated/asm/syscalls_64.h:41
do_syscall_x64 arch/x86/entry/common.c:52 [inline]
do_syscall_64+0xc9/0x1c0 arch/x86/entry/common.c:83
entry_SYSCALL_64_after_hwframe+0x77/0x7f

value changed: 0x0000000000000035 -> 0x0000000000000030

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 UID: 0 PID: 3583 Comm: syz.2.33 Not tainted 6.12.0-rc4-syzkaller-00261-g850925a8133c #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 09/13/2024
==================================================================


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[syzbot]

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