=============================
WARNING: suspicious RCU usage
6.16.0-rc5-syzkaller-00159-g47c84997c686-dirty #0 Not tainted
-----------------------------
drivers/net/ppp/ppp_generic.c:666 suspicious rcu_dereference_protected() usage!

other info that might help us debug this:


rcu_scheduler_active = 2, debug_locks = 1
2 locks held by syz.2.62/6181:
 #0: ffffffff8ecf3e08 (ppp_mutex){+.+.}-{4:4}, at: ppp_ioctl+0xcd/0x19a0
 #1: ffff888022259248 (&pch->upl){+...}-{3:3}, at: ppp_bridge_channels+0x1f3/0x640

stack backtrace:
CPU: 1 UID: 0 PID: 6181 Comm: syz.2.62 Not tainted 6.16.0-rc5-syzkaller-00159-g47c84997c686-dirty #0 PREEMPT(full) 
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.2-debian-1.16.2-1 04/01/2014
Call Trace:
 <TASK>
 dump_stack_lvl+0x189/0x250
 lockdep_rcu_suspicious+0x140/0x1d0
 ppp_bridge_channels+0x59f/0x640
 ppp_ioctl+0xce7/0x19a0
 __se_sys_ioctl+0xfc/0x170
 do_syscall_64+0xfa/0x3b0
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f540038e929
Code: ff ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 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 a8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007f5401111038 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffda RBX: 00007f54005b5fa0 RCX: 00007f540038e929
RDX: 0000200000000200 RSI: 0000000040047435 RDI: 0000000000000007
RBP: 00007f5400410b39 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 0000000000000000 R14: 00007f54005b5fa0 R15: 00007ffd048f5668
 </TASK>
