Re: 2.6.1[78] page allocation failure. order:3, mode:0x20
From: Auke Kok
Date: Fri Sep 22 2006 - 13:18:04 EST
Andrew Morton wrote:
On Fri, 22 Sep 2006 07:27:18 +0000 (GMT)
Holger Kiehl <Holger.Kiehl@xxxxxx> wrote:
I get some of the "page allocation failure" errors. My hardware is 4 CPU
Opteron with one quad + one dual intel e1000 cards. Kernel is plain 2.6.18
and for two cards MTU is set to 9000.
Sep 21 21:03:15 athena kernel: vsftpd: page allocation failure. order:3, mode:0x20
Sep 21 21:03:15 athena kernel:
Sep 21 21:03:15 athena kernel: Call Trace:
Sep 21 21:03:15 athena kernel: <IRQ> [<ffffffff8024e516>] __alloc_pages+0x282/0x29b
Sep 21 21:03:15 athena kernel: [<ffffffff8807aa93>] :ip_tables:ipt_do_table+0x1eb/0x318
Sep 21 21:03:15 athena kernel: [<ffffffff8026614b>] cache_grow+0x134/0x33d
Sep 21 21:03:15 athena kernel: [<ffffffff8026664c>] cache_alloc_refill+0x189/0x1d7
Sep 21 21:03:15 athena kernel: [<ffffffff80266724>] __kmalloc+0x8a/0x94
Sep 21 21:03:15 athena kernel: [<ffffffff803b5438>] __alloc_skb+0x5c/0x123
Sep 21 21:03:15 athena kernel: [<ffffffff803b5f2e>] __netdev_alloc_skb+0x12/0x2d
Sep 21 21:03:15 athena kernel: [<ffffffff8033cb22>] e1000_alloc_rx_buffers+0x6f/0x2f3
Sep 21 21:03:15 athena kernel: [<ffffffff803d1234>] ip_local_deliver+0x173/0x23b
Sep 21 21:03:15 athena kernel: [<ffffffff8033d29a>] e1000_clean_rx_irq+0x4f4/0x514
Is OK, it's just a warning and it is expected - the kernel will recover.
I'm half-inclined to shut the warning up by sticking a __GFP_NOWARN in there.
But on the other hand, that warning is handy sometimes. How come kmalloc
decided to request a 32k hunk of memory when the MTU size is only 9k? Is
the driver doing something dumb?
else if (max_frame <= E1000_RXBUFFER_8192)
adapter->rx_buffer_len = E1000_RXBUFFER_8192;
else if (max_frame <= E1000_RXBUFFER_16384)
adapter->rx_buffer_len = E1000_RXBUFFER_16384;
It sure is.
This is going to cause an 9000-byte MTU to use a 16384-byte allocation.
e1000_alloc_rx_buffers() adds two bytes to that, so we do kmalloc(16386),
which causes the slab allocator to request 32768 bytes. All for a 9kbyte skb.
I wonder if we can't account for NET_IP_ALIGN when selecting bufsize, to get at
rid of at least 1 order size before we netdev_alloc_skb. This should make 9k
frames only kmalloc(16384) and thus stay within the 16k boundary. I hope.
Completely untested: don't commit :)
Auke
---
e1000: account for NET_IP_ALIGN when calculating bufsiz
Account for NET_IP_ALIGN when requesting buffer sizes from netdev_alloc_skb to
reduce slab allocation by half.
Signed-off-by: Auke Kok <auke-jan.h.kok@xxxxxxxxx>
diff --git a/drivers/net/e1000/e1000_main.c b/drivers/net/e1000/e1000_main.c
index bb0d129..20b1f39 100644
--- a/drivers/net/e1000/e1000_main.c
+++ b/drivers/net/e1000/e1000_main.c
@@ -1144,7 +1144,7 @@ #endif
pci_read_config_word(pdev, PCI_COMMAND, &hw->pci_cmd_word);
- adapter->rx_buffer_len = MAXIMUM_ETHERNET_VLAN_SIZE;
+ adapter->rx_buffer_len = MAXIMUM_ETHERNET_VLAN_SIZE + NET_IP_ALIGN;
adapter->rx_ps_bsize0 = E1000_RXBUFFER_128;
hw->max_frame_size = netdev->mtu +
ENET_HEADER_SIZE + ETHERNET_FCS_SIZE;
@@ -3234,26 +3234,27 @@ #define MAX_STD_JUMBO_FRAME_SIZE 9234
* larger slab size
* i.e. RXBUFFER_2048 --> size-4096 slab */
- if (max_frame <= E1000_RXBUFFER_256)
+ if (max_frame + NET_IP_ALIGN <= E1000_RXBUFFER_256)
adapter->rx_buffer_len = E1000_RXBUFFER_256;
- else if (max_frame <= E1000_RXBUFFER_512)
+ else if (max_frame + NET_IP_ALIGN <= E1000_RXBUFFER_512)
adapter->rx_buffer_len = E1000_RXBUFFER_512;
- else if (max_frame <= E1000_RXBUFFER_1024)
+ else if (max_frame + NET_IP_ALIGN <= E1000_RXBUFFER_1024)
adapter->rx_buffer_len = E1000_RXBUFFER_1024;
- else if (max_frame <= E1000_RXBUFFER_2048)
+ else if (max_frame + NET_IP_ALIGN <= E1000_RXBUFFER_2048)
adapter->rx_buffer_len = E1000_RXBUFFER_2048;
- else if (max_frame <= E1000_RXBUFFER_4096)
+ else if (max_frame + NET_IP_ALIGN <= E1000_RXBUFFER_4096)
adapter->rx_buffer_len = E1000_RXBUFFER_4096;
- else if (max_frame <= E1000_RXBUFFER_8192)
+ else if (max_frame + NET_IP_ALIGN <= E1000_RXBUFFER_8192)
adapter->rx_buffer_len = E1000_RXBUFFER_8192;
- else if (max_frame <= E1000_RXBUFFER_16384)
+ else
adapter->rx_buffer_len = E1000_RXBUFFER_16384;
/* adjust allocation if LPE protects us, and we aren't using SBP */
if (!adapter->hw.tbi_compatibility_on &&
((max_frame == MAXIMUM_ETHERNET_FRAME_SIZE) ||
(max_frame == MAXIMUM_ETHERNET_VLAN_SIZE)))
- adapter->rx_buffer_len = MAXIMUM_ETHERNET_VLAN_SIZE;
+ adapter->rx_buffer_len = MAXIMUM_ETHERNET_VLAN_SIZE
+ + NET_IP_ALIGN;
netdev->mtu = new_mtu;
@@ -4076,7 +4076,8 @@ e1000_alloc_rx_buffers(struct e1000_adap
struct e1000_buffer *buffer_info;
struct sk_buff *skb;
unsigned int i;
- unsigned int bufsz = adapter->rx_buffer_len + NET_IP_ALIGN;
+ /* we have already accounted for NET_IP_ALIGN */
+ unsigned int bufsz = adapter->rx_buffer_len;
i = rx_ring->next_to_use;
buffer_info = &rx_ring->buffer_info[i];
-
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