[v5.15] INFO: rcu detected stall in security_socket_connect (2)

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: eceeec79dbc6 Linux 5.15.210
git tree: linux-5.15.y
console output: https://syzkaller.appspot.com/x/log.txt?x=1779b46e580000
kernel config: https://syzkaller.appspot.com/x/.config?x=6a0cae3abafc69
dashboard link: https://syzkaller.appspot.com/bug?extid=90d5f13c6bcebcbff436
compiler: Debian clang version 22.1.6 (++20260514074242+fc4aad7b5db3-1~exp1~20260514074407.73), Debian LLD 22.1.6

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

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/a8f82a67235a/disk-eceeec79.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/f10abb6026a6/vmlinux-eceeec79.xz
kernel image: https://storage.googleapis.com/syzbot-assets/ade6c70761ba/bzImage-eceeec79.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+90d5f1...@syzkaller.appspotmail.com

rcu: INFO: rcu_preempt self-detected stall on CPU
rcu: 0-...!: (10832 ticks this GP) idle=577/1/0x4000000000000000 softirq=18378/18380 fqs=338
(t=10502 jiffies g=23401 q=324)
rcu: rcu_preempt kthread starved for 9637 jiffies! g23401 f0x0 RCU_GP_WAIT_FQS(5) ->state=0x0 ->cpu=1
rcu: Unless rcu_preempt kthread gets sufficient CPU time, OOM is now expected behavior.
rcu: RCU grace-period kthread stack dump:
task:rcu_preempt state:R running task stack:28112 pid: 15 ppid: 2 flags:0x00004000
Call Trace:
<TASK>
context_switch kernel/sched/core.c:5049 [inline]
__schedule+0x11c3/0x4350 kernel/sched/core.c:6395
schedule+0x11b/0x1e0 kernel/sched/core.c:6478
schedule_timeout+0x184/0x2d0 kernel/time/timer.c:2117
rcu_gp_fqs_loop+0x2be/0x11f0 kernel/rcu/tree.c:1972
rcu_gp_kthread+0x9a/0x370 kernel/rcu/tree.c:2145
kthread+0x42e/0x520 kernel/kthread.c:334
ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:287
</TASK>
rcu: Stack dump where RCU GP kthread last ran:
Sending NMI from CPU 0 to CPUs 1:
NMI backtrace for cpu 1 skipped: idling at native_safe_halt arch/x86/include/asm/irqflags.h:51 [inline]
NMI backtrace for cpu 1 skipped: idling at arch_safe_halt arch/x86/include/asm/irqflags.h:89 [inline]
NMI backtrace for cpu 1 skipped: idling at default_idle+0xb/0x10 arch/x86/kernel/process.c:729
NMI backtrace for cpu 0
CPU: 0 PID: 7833 Comm: syz.2.891 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/09/2026
Call Trace:
<IRQ>
dump_stack_lvl+0x188/0x250 lib/dump_stack.c:106
nmi_cpu_backtrace+0x3a2/0x3d0 lib/nmi_backtrace.c:111
nmi_trigger_cpumask_backtrace+0x163/0x280 lib/nmi_backtrace.c:62
trigger_single_cpu_backtrace include/linux/nmi.h:166 [inline]
rcu_dump_cpu_stacks+0x22d/0x380 kernel/rcu/tree_stall.h:349
print_cpu_stall+0x31f/0x5f0 kernel/rcu/tree_stall.h:633
check_cpu_stall kernel/rcu/tree_stall.h:727 [inline]
rcu_pending kernel/rcu/tree.c:3936 [inline]
rcu_sched_clock_irq+0x6ec/0x1120 kernel/rcu/tree.c:2619
update_process_times+0x193/0x200 kernel/time/timer.c:2021
tick_sched_handle kernel/time/tick-sched.c:254 [inline]
tick_sched_timer+0x37d/0x560 kernel/time/tick-sched.c:1473
__run_hrtimer kernel/time/hrtimer.c:1685 [inline]
__hrtimer_run_queues+0x4b0/0xb60 kernel/time/hrtimer.c:1749
hrtimer_interrupt+0x397/0x8b0 kernel/time/hrtimer.c:1811
local_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1097 [inline]
__sysvec_apic_timer_interrupt+0x137/0x4a0 arch/x86/kernel/apic/apic.c:1114
instr_sysvec_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1108 [inline]
sysvec_apic_timer_interrupt+0x9b/0xc0 arch/x86/kernel/apic/apic.c:1108
</IRQ>
<TASK>
asm_sysvec_apic_timer_interrupt+0x16/0x20 arch/x86/include/asm/idtentry.h:676
RIP: 0010:__sanitizer_cov_trace_pc+0x41/0x60 kernel/kcov.c:211
Code: ff 00 74 11 81 fa 00 01 00 00 75 35 83 b9 34 16 00 00 00 74 2c 8b 91 10 16 00 00 83 fa 02 75 21 48 8b 91 18 16 00 00 48 8b 32 <48> 8d 7e 01 8b 89 14 16 00 00 48 39 cf 73 08 48 89 44 f2 08 48 89
RSP: 0018:ffffc90002e6f8c8 EFLAGS: 00000246
RAX: ffffffff8405ef89 RBX: 0000000000000000 RCX: ffff88807de29dc0
RDX: ffffc9000c551000 RSI: 000000000007ffff RDI: ffffc90002e6fa81
RBP: ffffffff8a737188 R08: 0000000000000000 R09: 0000000000000004
R10: dffffc0000000000 R11: fffff520005cdf50 R12: ffffc90002e6fa81
R13: ffffc90002e6fa88 R14: 0000000000000008 R15: dffffc0000000000
vsnprintf+0x12f9/0x1c20 lib/vsprintf.c:2761
tomoyo_supervisor+0x183/0x1190 security/tomoyo/common.c:2069
tomoyo_audit_net_log security/tomoyo/network.c:367 [inline]
tomoyo_audit_unix_log security/tomoyo/network.c:406 [inline]
tomoyo_unix_entry security/tomoyo/network.c:574 [inline]
tomoyo_check_unix_address+0x4a6/0x720 security/tomoyo/network.c:605
tomoyo_socket_connect_permission+0x186/0x270 security/tomoyo/network.c:709
security_socket_connect+0x6c/0xa0 security/security.c:2238
__sys_connect_file net/socket.c:1929 [inline]
__sys_connect+0x30f/0x450 net/socket.c:1950
__do_sys_connect net/socket.c:1960 [inline]
__se_sys_connect net/socket.c:1957 [inline]
__x64_sys_connect+0x76/0x80 net/socket.c:1957
do_syscall_x64 arch/x86/entry/common.c:50 [inline]
do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:80
entry_SYSCALL_64_after_hwframe+0x66/0xd0
RIP: 0033:0x7ff01a412e59
Code: ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 44 00 00 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 e8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007ff01866c028 EFLAGS: 00000246 ORIG_RAX: 000000000000002a
RAX: ffffffffffffffda RBX: 00007ff01a68bfa0 RCX: 00007ff01a412e59
RDX: 000000000000006e RSI: 0000200000000440 RDI: 0000000000000004
RBP: 00007ff01a4a8e6f R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007ff01a68c038 R14: 00007ff01a68bfa0 R15: 00007fff45a588d8
</TASK>


---
This report is generated by a bot. It may contain errors.
See https://goo.gl/tpsmEJ for more information about syzbot.
syzbot engineers can be reached at syzk...@googlegroups.com.

syzbot will keep track of this issue. See:
https://goo.gl/tpsmEJ#status for how to communicate with syzbot.

If the report is already addressed, let syzbot know by replying with:
#syz fix: exact-commit-title

If you want to overwrite report's subsystems, reply with:
#syz set subsystems: new-subsystem
(See the list of subsystem names on the web dashboard)

If the report is a duplicate of another one, reply with:
#syz dup: exact-subject-of-another-report

If you want to undo deduplication, reply with:
#syz undup