From: Matt Mackall <mpm@selenic.com>
To: Tobias Diedrich <ranma@tdiedrich.de>
Cc: linux-kernel@vger.kernel.org
Subject: Re: netconsole: tulip: possible remote DoS? due to kernel freeze on heavy RX traffic after Order-1 allocation failure
Date: Thu, 05 Nov 2009 23:13:04 -0600 [thread overview]
Message-ID: <1257484384.2873.618.camel@calx> (raw)
In-Reply-To: <20091106032754.GA15429@yumi.tdiedrich.de>
On Fri, 2009-11-06 at 04:27 +0100, Tobias Diedrich wrote:
> Matt Mackall wrote:
> > > Example from netconsole log:
> > > |perl: page allocation failure. order:1, mode:0x20
> > > |Pid: 3541, comm: perl Tainted: G W 2.6.30.9-tomodachi #16
> > > |Call Trace:
> > > | [<c013e56d>] ? __alloc_pages_internal+0x353/0x36f
> > > | [<c0154f2c>] ? cache_alloc_refill+0x2ab/0x544
> > > | [<c0355479>] ? dev_alloc_skb+0x11/0x25
> > > | [<c015526f>] ? __kmalloc_track_caller+0xaa/0xf9
> > > | [<c0354ae5>] ? __alloc_skb+0x48/0xff
> > > | [<c0355479>] ? dev_alloc_skb+0x11/0x25
> > > | [<c02d4ba9>] ? tulip_refill_rx+0x3c/0x115
> > > | [<c02d4fff>] ? tulip_poll+0x37d/0x416
> > > | [<c0359763>] ? net_rx_action+0x6b/0x12f
> > > | [<c0121ad7>] ? __do_softirq+0x4e/0xbf
> > > | [<c0121a89>] ? __do_softirq+0x0/0xbf
> > > | <IRQ> [<c0107700>] ? do_IRQ+0x53/0x63
> > > | [<c0106610>] ? common_interrupt+0x30/0x38
> >
> > I don't see anything in this trace to implicate netconsole? This is the
> > normal network receive path running out of input buffers then running
> > into memory fragmentation.
>
> I'm just thinking the hang might be related to using netconsole.
> I guess I should try reproducing it without it.
You should, though I'd be surprised if it matters.
> Or is it normal that a box will hang if the network receive path runs out of
> input buffers?
No, it's not normal.
> Why does it allocate Order-1 buffers anyway?
Your skbs are allocated via the SLAB allocator, which packs 5 skbs into
an order-1 buffer rather than 4 into 2 order-0 buffers.
Running out of order-1 buffers hasn't been a problem for most people
lately though - is there anything interesting about your workload? Lots
of threads? NFS? Long network processing latencies?
--
http://selenic.com : development and support for Mercurial and Linux
next prev parent reply other threads:[~2009-11-06 5:13 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2009-11-05 11:31 netconsole: tulip: possible remote DoS? due to kernel freeze on heavy RX traffic after Order-1 allocation failure Tobias Diedrich
2009-11-05 19:49 ` Matt Mackall
2009-11-06 3:27 ` Tobias Diedrich
2009-11-06 5:13 ` Matt Mackall [this message]
2009-11-06 5:25 ` Tobias Diedrich
2009-11-06 5:49 ` Tobias Diedrich
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