=============================
WARNING: suspicious RCU usage
syzkaller #0 Not tainted
-----------------------------
net/sched/sch_api.c:304 suspicious rcu_dereference_protected() usage!
other info that might help us debug this:
rcu_scheduler_active = 2, debug_locks = 1
6 locks held by syz-executor/8565:
#0: ffff88805f7d8460 (sb_writers#3){.+.+}-{0:0}, at: mnt_want_write+0x3d/0x90 fs/namespace.c:386
#1: ffff88807b042e00 (&type->i_mutex_dir_key#3/1){+.+.}-{3:3}, at: inode_lock_nested include/linux/fs.h:822 [inline]
#1: ffff88807b042e00 (&type->i_mutex_dir_key#3/1){+.+.}-{3:3}, at: do_unlinkat+0x1b9/0x6f0 fs/namei.c:4339
#2: ffffffff8c6ad298 (tomoyo_ss){....}-{0:0}, at: rcu_lock_acquire+0x5/0x30 include/linux/rcupdate.h:312
#3: ffffc90000007c00 ((&q->perturb_timer)){+.-.}-{0:0}, at: lockdep_copy_map include/linux/lockdep.h:45 [inline]
#3: ffffc90000007c00 ((&q->perturb_timer)){+.-.}-{0:0}, at: call_timer_fn+0xbb/0x530 kernel/time/timer.c:1441
#4: ffff88807b2b1908 (&sch->q.lock){+.-.}-{2:2}, at: spin_lock include/linux/spinlock.h:364 [inline]
#4: ffff88807b2b1908 (&sch->q.lock){+.-.}-{2:2}, at: sfq_perturbation+0x12e/0x2060 net/sched/sch_sfq.c:610
#5: ffffffff8c11c760 (rcu_read_lock){....}-{1:2}, at: rcu_lock_acquire+0x5/0x30 include/linux/rcupdate.h:312
stack backtrace:
CPU: 0 PID: 8565 Comm: syz-executor Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/02/2025
Call Trace:
dump_stack_lvl+0x168/0x230 lib/dump_stack.c:106
qdisc_lookup+0xa6/0x650 net/sched/sch_api.c:304
qdisc_tree_reduce_backlog+0x190/0x430 net/sched/sch_api.c:793
sfq_rehash net/sched/sch_sfq.c:598 [inline]
sfq_perturbation+0x1f20/0x2060 net/sched/sch_sfq.c:613
call_timer_fn+0x16c/0x530 kernel/time/timer.c:1451
expire_timers kernel/time/timer.c:1496 [inline]
__run_timers+0x525/0x7c0 kernel/time/timer.c:1767
handle_softirqs+0x328/0x820 kernel/softirq.c:576
__do_softirq kernel/softirq.c:610 [inline]
invoke_softirq kernel/softirq.c:450 [inline]
__irq_exit_rcu+0x12f/0x220 kernel/softirq.c:659
irq_exit_rcu+0x5/0x20 kernel/softirq.c:671
instr_sysvec_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1108 [inline]
sysvec_apic_timer_interrupt+0xa0/0xc0 arch/x86/kernel/apic/apic.c:1108
asm_sysvec_apic_timer_interrupt+0x16/0x20 arch/x86/include/asm/idtentry.h:676
RIP: 0010:__raw_spin_unlock_irqrestore include/linux/spinlock_api_smp.h:161 [inline]
RIP: 0010:_raw_spin_unlock_irqrestore+0xa5/0x100 kernel/locking/spinlock.c:194
Code: 74 05 e8 de 0d cb f7 48 c7 44 24 20 00 00 00 00 9c 8f 44 24 20 f6 44 24 21 02 75 4b f7 c3 00 02 00 00 74 01 fb bf 01 00 00 00 f6 95 9e f7 65 8b 05 87 93 4f 76 85 c0 74 3c 48 c7 04 24 0e 36
RSP: 0018:ffffc90002f1f820 EFLAGS: 00000206
RAX: 2ce6192d0c4e5800 RBX: 0000000000000a02 RCX: 2ce6192d0c4e5800
RDX: dffffc0000000000 RSI: ffffffff8a0b1c60 RDI: 0000000000000001
RBP: ffffc90002f1f8b8 R08: dffffc0000000000 R09: fffffbfff1ff7c2f
R10: fffffbfff1ff7c2f R11: 1ffffffff1ff7c2e R12: dffffc0000000000
R13: ffff8880168409c0 R14: ffff8880168409c0 R15: 1ffff920005e3f04
spin_unlock_irqrestore include/linux/spinlock.h:419 [inline]
get_partial_node+0x233/0x250 mm/slub.c:2157
get_partial mm/slub.c:2237 [inline]
___slab_alloc+0x5b9/0xdf0 mm/slub.c:3008
__slab_alloc mm/slub.c:3100 [inline]
slab_alloc_node mm/slub.c:3191 [inline]
slab_alloc mm/slub.c:3233 [inline]
__kmalloc+0x1cd/0x330 mm/slub.c:4408
kmalloc include/linux/slab.h:612 [inline]
tomoyo_realpath_from_path+0x118/0x610 security/tomoyo/realpath.c:254
tomoyo_get_realpath security/tomoyo/file.c:151 [inline]
tomoyo_path_perm+0x1cd/0x510 security/tomoyo/file.c:822
tomoyo_path_unlink+0x9f/0xe0 security/tomoyo/tomoyo.c:149
security_path_unlink+0xd8/0x130 security/security.c:1170
do_unlinkat+0x2ed/0x6f0 fs/namei.c:4352
__do_sys_unlink fs/namei.c:4404 [inline]
__se_sys_unlink fs/namei.c:4402 [inline]
__x64_sys_unlink+0x45/0x50 fs/namei.c:4402
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: 0033:0x7ff9db5a6577
Code: 73 01 c3 48 c7 c1 a8 ff ff ff f7 d8 64 89 01 48 83 c8 ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 44 00 00 b8 57 00 00 00 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 a8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007ffd5846f0c8 EFLAGS: 00000206 ORIG_RAX: 0000000000000057
RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 00007ff9db5a6577
RDX: 00007ffd5846f0f0 RSI: 00007ffd5846f180 RDI: 00007ffd5846f180
RBP: 00007ffd5846f180 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000100 R11: 0000000000000206 R12: 00007ffd58470210
R13: 00007ff9db629d7d R14: 00000000000b6091 R15: 00007ffd58470250
vkms_vblank_simulate: vblank timer overrun
----------------
Code disassembly (best guess):
0: 74 05 je 0x7
2: e8 de 0d cb f7 call 0xf7cb0de5
7: 48 c7 44 24 20 00 00 movq $0x0,0x20(%rsp)
e: 00 00
10: 9c pushf
11: 8f 44 24 20 pop 0x20(%rsp)
15: f6 44 24 21 02 testb $0x2,0x21(%rsp)
1a: 75 4b jne 0x67
1c: f7 c3 00 02 00 00 test $0x200,%ebx
22: 74 01 je 0x25
24: fb sti
25: bf 01 00 00 00 mov $0x1,%edi
* 2a: e8 f6 95 9e f7 call 0xf79e9625 <-- trapping instruction
2f: 65 8b 05 87 93 4f 76 mov %gs:0x764f9387(%rip),%eax # 0x764f93bd
36: 85 c0 test %eax,%eax
38: 74 3c je 0x76
3a: 48 rex.W
3b: c7 .byte 0xc7
3c: 04 24 add $0x24,%al
3e: 0e (bad)
3f: 36 ss