[v6.6] INFO: rcu detected stall in security_file_ioctl (2)

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: 924b4a879cbb Linux 6.6.142
git tree: linux-6.6.y
console output: https://syzkaller.appspot.com/x/log.txt?x=17accf2e580000
kernel config: https://syzkaller.appspot.com/x/.config?x=90249d2d52c08134
dashboard link: https://syzkaller.appspot.com/bug?extid=8da2753ee992b535f7de
compiler: Debian clang version 21.1.8 (++20251221033036+2078da43e25a-1~exp1~20251221153213.50), Debian LLD 21.1.8
syz repro: https://syzkaller.appspot.com/x/repro.syz?x=16da03d2580000
C reproducer: https://syzkaller.appspot.com/x/repro.c?x=129de1b6580000

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/bd13425862f1/disk-924b4a87.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/eaa5de9e440b/vmlinux-924b4a87.xz
kernel image: https://storage.googleapis.com/syzbot-assets/5a9aa3293c15/bzImage-924b4a87.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+8da275...@syzkaller.appspotmail.com

rcu: INFO: rcu_preempt detected stalls on CPUs/tasks:
rcu: Tasks blocked on level-0 rcu_node (CPUs 0-1): P5783/1:b..l
rcu: (detected by 0, t=10502 jiffies, g=6773, q=29 ncpus=2)
task:syz-executor368 state:R running task stack:25136 pid:5783 ppid:5781 flags:0x00004002
Call Trace:
<TASK>
context_switch kernel/sched/core.c:5381 [inline]
__schedule+0x1553/0x45a0 kernel/sched/core.c:6700
preempt_schedule_irq+0xbf/0x150 kernel/sched/core.c:7010
irqentry_exit+0x67/0x70 kernel/entry/common.c:438
asm_sysvec_apic_timer_interrupt+0x1a/0x20 arch/x86/include/asm/idtentry.h:687
RIP: 0010:lock_acquire+0x208/0x420 kernel/locking/lockdep.c:5758
Code: f7 84 24 80 00 00 00 00 02 00 00 43 c6 44 3c 04 f8 0f 85 f0 00 00 00 41 f7 c6 00 02 00 00 74 01 fb 48 c7 44 24 60 0e 36 e0 45 <4b> c7 04 3c 00 00 00 00 43 c7 44 3c 08 00 00 00 00 65 48 8b 04 25
RSP: 0018:ffffc9000466f760 EFLAGS: 00000206
RAX: 0000000000000001 RBX: 0000000000000000 RCX: 84ccc8cf60b64800
RDX: 0000000000000000 RSI: ffffffff8acadd60 RDI: ffffffff8b1c9c20
RBP: ffffc9000466f868 R08: dffffc0000000000 R09: 1ffffffff2239aa0
R10: dffffc0000000000 R11: fffffbfff2239aa1 R12: 1ffff920008cdef8
R13: ffffffff8d132160 R14: 0000000000000246 R15: dffffc0000000000
rcu_lock_acquire include/linux/rcupdate.h:334 [inline]
rcu_read_lock include/linux/rcupdate.h:786 [inline]
tomoyo_sys_getppid security/tomoyo/common.h:1135 [inline]
tomoyo_print_header security/tomoyo/audit.c:170 [inline]
tomoyo_init_log+0x310/0x1f50 security/tomoyo/audit.c:255
tomoyo_supervisor+0x363/0x1170 security/tomoyo/common.c:2089
tomoyo_audit_path_number_log security/tomoyo/file.c:235 [inline]
tomoyo_path_number_perm+0x4a9/0x620 security/tomoyo/file.c:734
security_file_ioctl+0x70/0xa0 security/security.c:2648
__do_sys_ioctl fs/ioctl.c:865 [inline]
__se_sys_ioctl+0x48/0x170 fs/ioctl.c:857
do_syscall_x64 arch/x86/entry/common.c:46 [inline]
do_syscall_64+0x55/0xb0 arch/x86/entry/common.c:76
entry_SYSCALL_64_after_hwframe+0x68/0xd2
RIP: 0033:0x7f920e3536f9
RSP: 002b:00007ffc3006d5b8 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 00007f920e3536f9
RDX: 0000200000000140 RSI: 000000004068aea3 RDI: 0000000000000005
RBP: 00000000000f4240 R08: 0000000000000009 R09: 0000000000000009
R10: 0000000000000009 R11: 0000000000000246 R12: 00007ffc3006d738
R13: 0000000000000002 R14: 00007ffc3006d5e0 R15: 00007ffc3006d5d0
</TASK>
rcu: rcu_preempt kthread starved for 10538 jiffies! g6773 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:26888 pid:17 ppid:2 flags:0x00004000
Call Trace:
<TASK>
context_switch kernel/sched/core.c:5381 [inline]
__schedule+0x1553/0x45a0 kernel/sched/core.c:6700
schedule+0xbd/0x170 kernel/sched/core.c:6774
schedule_timeout+0x188/0x2d0 kernel/time/timer.c:2168
rcu_gp_fqs_loop+0x313/0x1590 kernel/rcu/tree.c:1667
rcu_gp_kthread+0x9d/0x3b0 kernel/rcu/tree.c:1866
kthread+0x2fa/0x390 kernel/kthread.c:388
ret_from_fork+0x48/0x80 arch/x86/kernel/process.c:152
ret_from_fork_asm+0x11/0x20 arch/x86/entry/entry_64.S:293
</TASK>
rcu: Stack dump where RCU GP kthread last ran:
Sending NMI from CPU 0 to CPUs 1:
NMI backtrace for cpu 1
CPU: 1 PID: 5787 Comm: syz-executor368 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 04/18/2026
RIP: 0010:task_irq_context kernel/locking/lockdep.c:4607 [inline]
RIP: 0010:__lock_acquire+0x48a/0x7d40 kernel/locking/lockdep.c:5074
Code: 00 00 00 00 00 fc ff df 4c 89 b4 24 b0 00 00 00 48 8b 45 10 49 89 06 65 8b 05 be 4d 9a 7e 45 31 f6 85 c0 41 0f 95 c6 45 01 f6 <48> 8b 44 24 20 4c 8d a0 c4 0a 00 00 4c 89 e0 48 c1 e8 03 48 89 84
RSP: 0018:ffffc900046feda0 EFLAGS: 00000046
RAX: 0000000000000000 RBX: 0000000000000000 RCX: 1ffff1100f35f16a
RDX: ffff888079af8b28 RSI: 0000000000000002 RDI: ffff888079af8b38
RBP: ffffc900046fefe8 R08: dffffc0000000000 R09: 0000000000000001
R10: dffffc0000000000 R11: fffffbfff1d16cce R12: ffff888079af8b40
R13: 0000000000000689 R14: 0000000000000000 R15: 0000000000000000
FS: 00005555869543c0(0000) GS:ffff8880b8f00000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 000055e58ca74cb8 CR3: 0000000074ed7000 CR4: 00000000003526e0
Call Trace:
<TASK>
lock_acquire+0x19e/0x420 kernel/locking/lockdep.c:5754
seqcount_lockdep_reader_access+0x116/0x1d0 include/linux/seqlock.h:102
get_kvmclock+0xf9/0x760 arch/x86/kvm/x86.c:3094
get_kvmclock_ns+0x3e/0x60 arch/x86/kvm/x86.c:3103
get_time_ref_counter+0xb4/0x180 arch/x86/kvm/hyperv.c:579
kvm_hv_process_stimers+0x23e/0x1680 arch/x86/kvm/hyperv.c:881
vcpu_enter_guest arch/x86/kvm/x86.c:10719 [inline]
vcpu_run+0x2e19/0x7450 arch/x86/kvm/x86.c:11078
kvm_arch_vcpu_ioctl_run+0xfd6/0x1850 arch/x86/kvm/x86.c:11307
kvm_vcpu_ioctl+0x8fb/0xc10 virt/kvm/kvm_main.c:4162
vfs_ioctl fs/ioctl.c:51 [inline]
__do_sys_ioctl fs/ioctl.c:871 [inline]
__se_sys_ioctl+0xfd/0x170 fs/ioctl.c:857
do_syscall_x64 arch/x86/entry/common.c:46 [inline]
do_syscall_64+0x55/0xb0 arch/x86/entry/common.c:76
entry_SYSCALL_64_after_hwframe+0x68/0xd2
RIP: 0033:0x7f920e3536f9
Code: c0 79 93 eb d5 48 8d 7c 1d 00 eb 99 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 d8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007ffc3006d5b8 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 00007f920e3536f9
RDX: 0000000000000000 RSI: 000000000000ae80 RDI: 0000000000000005
RBP: 00000000000f4240 R08: 0000000000000009 R09: 0000000000000009
R10: 0000000000000009 R11: 0000000000000246 R12: 00007ffc3006d738
R13: 0000000000000002 R14: 00007ffc3006d5e0 R15: 00007ffc3006d5d0
</TASK>
INFO: NMI handler (nmi_cpu_backtrace_handler) took too long to run: 1.221 msecs
sched: RT throttling activated


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