Date: Mon, 15 Nov 2004 04:46:38 -0800
From: bugme-daemon@osdl.org
To: bugme-new@lists.osdl.org
Subject: [Bugme-new] [Bug 3747] New: HTB causes machine lockups

I have some network traffic shaping rules used on a Linux box. For example I
have hundreds of them on eth1. I am using HTB in all cases (sometimes attaching
SFQ to HTB rules). Everything works fine, until I issue:

tc qdisc del dev eth1 root

Which causes a machine lockup. Sometimes it happens day after day, but sometimes
once a month. There are no traces in logs, no oopses, and so on. Machine just
freezes (you see login on your screen, but can't type anything, can't ping that
machine, ctrl-alt-del or sysrq doesn't work). Problem was on kernels from 2.4.21
up to 2.4.26. Haven't tried 2.4.27 and 2.6.x on that box yet.

Steps to reproduce:
Hard to tell really. You need to set up a script creating hunderds of HTB rules
and regenerating them every (let say) 15 minutes, issuing 'tc qdisc del dev
ethX' everytime.

Did you ever experience the same problems with other classful qdiscs such as
CBQ? Would it be possible for you to run a similar CBQ setup on a dummy device
and see if it happens as well? Is anything going on at the time of the
deadlocks like an interface going down etc.?