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Message-ID: <4DA49332.8000403@lwfinger.net>
Date: Tue, 12 Apr 2011 13:00:18 -0500
From: Larry Finger <Larry.Finger@lwfinger.net>
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To: Igor Plyatov <plyatov@gmail.com>
CC: linux-wireless@vger.kernel.org
Subject: Re: rt2800usb: page allocation failure
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On 04/12/2011 10:38 AM, Igor Plyatov wrote:

> kworker/u:1: page allocation failure. order:1, mode:0x20

--snip--

> [<c0279450>] (dev_alloc_skb+0x0/0x44) from [<c0226698>]
> (rt2x00queue_alloc_rxskb+0x4c/0xc4)
> [<c022664c>] (rt2x00queue_alloc_rxskb+0x0/0xc4) from [<c0223480>]
> (rt2x00lib_rxdone+0x44/0x298)

--snip--

> Normal: 403*4kB 2*8kB 2*16kB 2*32kB 0*64kB 0*128kB 0*256kB 0*512kB 0*1024kB
> 0*2048kB 0*4096kB = 1724kB

Your system is failing to get a receive buffer of size 8kB (order:1). If we look 
at the last line above, you have quite a bit of memory free, but it is highly 
fragmented - almost all of it is in 4kB pieces. This condition is not fatal, but 
it can be avoided by changing the NIC parameters so that each RX buffer fits in 4k.

If you look at the ifconfig output for this device, the MTU is likely 1500. By 
reducing this, you should be able to get all buffers to be of order 0. I would 
start with 1400 to see if it makes the problem go away. Reducing this quantity 
has the potential to slow the network transfers, but you won't see it as the 
default block size for dd is 512. Any such slowdown will be much less severe 
than the delay causes by missing a buffer allocation.

Larry