From mboxrd@z Thu Jan  1 00:00:00 1970
From: Patrick McHardy <kaber@trash.net>
Subject: Re: net_sched 00/07: classful multiqueue dummy scheduler
Date: Mon, 07 Sep 2009 19:33:53 +0200
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References: <20090904164111.27300.29929.sendpatchset@x2.localnet>	<4AA14377.9020200@trash.net> <20090907.015039.154939751.davem@davemloft.net> <4AA503E4.2060504@gmail.com> <4AA50ACF.9010400@trash.net> <4AA5175F.6030600@trash.net> <4AA54128.2050607@gmail.com> <4AA542B4.4090206@trash.net> <4AA54347.8020401@gmail.com>
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Cc: David Miller <davem@davemloft.net>, netdev@vger.kernel.org
To: Eric Dumazet <eric.dumazet@gmail.com>
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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-0xf6e62=
2bd. First byte 0x76 instead of 0x6b
>>> Sep  7 16:37:55 erd kernel: [  217.057049] INFO: Allocated in qdisc=
_alloc+0x1b/0x80 age=3D154593 cpu=3D2 pid=3D5165
>>> Sep  7 16:37:55 erd kernel: [  217.057094] INFO: Freed in qdisc_des=
troy+0x88/0xa0 age=3D139186 cpu=3D4 pid=3D5173
>>> Sep  7 16:37:55 erd kernel: [  217.057139] INFO: Slab 0xc16ddc40 ob=
jects=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?
>>
>=20
> Sorry, this was *before* your last patch.
>=20
> I tried to have more information, because I was not able to get conso=
le messages at crash time on this remote dev machine.
>=20
> enabling SLUB checks got some hint of what the problem was (using mem=
ory block after its freeing by qdisc_destroy)

OK, that probably explains it, the spinlock operations were operating
on already freed memory.

I'll do some more testing and will send the final patch if no
other problems show up.