=============================
WARNING: suspicious RCU usage
6.16.0-rc2-syzkaller-00071-g74b4cc9b8780 #0 Not tainted
-----------------------------
net/core/netclassid_cgroup.c:23 suspicious rcu_dereference_check() usage!

other info that might help us debug this:


rcu_scheduler_active = 2, debug_locks = 1
1 lock held by syz.5.4568/24154:
 #0: ffffffff8e3c3d80 (rcu_read_lock_trace){....}-{0:0}, at: rcu_lock_acquire include/linux/rcupdate.h:331 [inline]
 #0: ffffffff8e3c3d80 (rcu_read_lock_trace){....}-{0:0}, at: rcu_read_lock_trace include/linux/rcupdate_trace.h:58 [inline]
 #0: ffffffff8e3c3d80 (rcu_read_lock_trace){....}-{0:0}, at: bpf_prog_test_run_syscall+0x344/0x780 net/bpf/test_run.c:1563

stack backtrace:
CPU: 3 UID: 0 PID: 24154 Comm: syz.5.4568 Not tainted 6.16.0-rc2-syzkaller-00071-g74b4cc9b8780 #0 PREEMPT(full) 
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.3-debian-1.16.3-2~bpo12+1 04/01/2014
Call Trace:
 <TASK>
 __dump_stack lib/dump_stack.c:94 [inline]
 dump_stack_lvl+0x16c/0x1f0 lib/dump_stack.c:120
 lockdep_rcu_suspicious+0x166/0x260 kernel/locking/lockdep.c:6871
 task_cls_state+0x1c9/0x1f0 net/core/netclassid_cgroup.c:23
 __task_get_classid include/net/cls_cgroup.h:50 [inline]
 ____bpf_get_cgroup_classid_curr net/core/filter.c:3088 [inline]
 bpf_get_cgroup_classid_curr+0x1a/0x60 net/core/filter.c:3086
 bpf_prog_6102aa855c646698+0x22/0x75
 bpf_dispatcher_nop_func include/linux/bpf.h:1322 [inline]
 __bpf_prog_run include/linux/filter.h:718 [inline]
 bpf_prog_run include/linux/filter.h:725 [inline]
 bpf_prog_run_pin_on_cpu include/linux/filter.h:742 [inline]
 bpf_prog_test_run_syscall+0x3ad/0x780 net/bpf/test_run.c:1564
 bpf_prog_test_run kernel/bpf/syscall.c:4429 [inline]
 __sys_bpf+0x1485/0x4d80 kernel/bpf/syscall.c:5854
 __do_sys_bpf kernel/bpf/syscall.c:5943 [inline]
 __se_sys_bpf kernel/bpf/syscall.c:5941 [inline]
 __ia32_sys_bpf+0x76/0xe0 kernel/bpf/syscall.c:5941
 do_syscall_32_irqs_on arch/x86/entry/syscall_32.c:83 [inline]
 __do_fast_syscall_32+0x7c/0x3a0 arch/x86/entry/syscall_32.c:306
 do_fast_syscall_32+0x32/0x80 arch/x86/entry/syscall_32.c:331
 entry_SYSENTER_compat_after_hwframe+0x84/0x8e
RIP: 0023:0xf7fc5579
Code: b8 01 10 06 03 74 b4 01 10 07 03 74 b0 01 10 08 03 74 d8 01 00 00 00 00 00 00 00 00 00 00 00 00 00 51 52 55 89 e5 0f 34 cd 80 <5d> 5a 59 c3 90 90 90 90 8d b4 26 00 00 00 00 8d b4 26 00 00 00 00
RSP: 002b:00000000f50e655c EFLAGS: 00000296 ORIG_RAX: 0000000000000165
RAX: ffffffffffffffda RBX: 000000000000000a RCX: 0000000080000500
RDX: 0000000000000048 RSI: 0000000000000000 RDI: 0000000000000000
RBP: 0000000000000000 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000296 R12: 0000000000000000
R13: 0000000000000000 R14: 0000000000000000 R15: 0000000000000000
 </TASK>
----------------
Code disassembly (best guess), 2 bytes skipped:
   0:	10 06                	adc    %al,(%rsi)
   2:	03 74 b4 01          	add    0x1(%rsp,%rsi,4),%esi
   6:	10 07                	adc    %al,(%rdi)
   8:	03 74 b0 01          	add    0x1(%rax,%rsi,4),%esi
   c:	10 08                	adc    %cl,(%rax)
   e:	03 74 d8 01          	add    0x1(%rax,%rbx,8),%esi
  1e:	00 51 52             	add    %dl,0x52(%rcx)
  21:	55                   	push   %rbp
  22:	89 e5                	mov    %esp,%ebp
  24:	0f 34                	sysenter
  26:	cd 80                	int    $0x80
* 28:	5d                   	pop    %rbp <-- trapping instruction
  29:	5a                   	pop    %rdx
  2a:	59                   	pop    %rcx
  2b:	c3                   	ret
  2c:	90                   	nop
  2d:	90                   	nop
  2e:	90                   	nop
  2f:	90                   	nop
  30:	8d b4 26 00 00 00 00 	lea    0x0(%rsi,%riz,1),%esi
  37:	8d b4 26 00 00 00 00 	lea    0x0(%rsi,%riz,1),%esi