From mboxrd@z Thu Jan  1 00:00:00 1970
From: Eric Dumazet <eric.dumazet@gmail.com>
Subject: Re: net_sched 00/07: classful multiqueue dummy scheduler
Date: Mon, 07 Sep 2009 19:38:11 +0200
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Cc: David Miller <davem@davemloft.net>, netdev@vger.kernel.org
To: Patrick McHardy <kaber@trash.net>
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Patrick McHardy a =E9crit :
> Eric Dumazet wrote:
>> Patrick McHardy a =E9crit :
>>>> Sep  7 16:37:55 erd kernel: [  217.056813] =3D=3D=3D=3D=3D=3D=3D=3D=
=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=
=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=
=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D
>>>> Sep  7 16:37:55 erd kernel: [  217.056865] BUG kmalloc-256: Poison=
 overwritten
>>>> Sep  7 16:37:55 erd kernel: [  217.056910] -----------------------=
------------------------------------------------------
>>>> Sep  7 16:37:55 erd kernel: [  217.056911]
>>>> Sep  7 16:37:55 erd kernel: [  217.056990] INFO: 0xf6e622bc-0xf6e6=
22bd. First byte 0x76 instead of 0x6b
>>>> Sep  7 16:37:55 erd kernel: [  217.057049] INFO: Allocated in qdis=
c_alloc+0x1b/0x80 age=3D154593 cpu=3D2 pid=3D5165
>>>> Sep  7 16:37:55 erd kernel: [  217.057094] INFO: Freed in qdisc_de=
stroy+0x88/0xa0 age=3D139186 cpu=3D4 pid=3D5173
>>>> Sep  7 16:37:55 erd kernel: [  217.057139] INFO: Slab 0xc16ddc40 o=
bjects=3D26 used=3D6 fp=3D0xf6e62260 flags=3D0x28040c3
>>>> Sep  7 16:37:55 erd kernel: [  217.057184] INFO: Object 0xf6e62260=
 @offset=3D608 fp=3D0xf6e62850
>>>> Sep  7 16:37:55 erd kernel: [  217.057184]
>>> I'm unable to reproduce this. Could you send me the commands you
>>> used that lead to this?
>>>
>> Sorry, this was *before* your last patch.
>>
>> I tried to have more information, because I was not able to get cons=
ole messages at crash time on this remote dev machine.
>>
>> enabling SLUB checks got some hint of what the problem was (using me=
mory block after its freeing by qdisc_destroy)
>=20
> OK, that probably explains it, the spinlock operations were operating
> on already freed memory.
>=20
> I'll do some more testing and will send the final patch if no
> other problems show up.

BTW, you may ignore rate estimation requests on the mq root, since its =
stats
are updated only by user request, when doing a "tc -s -q qdisc" command=
, while
estimator is fired by a cyclic timer...