On Fri, 22 Sep 2006, Andrew Morton wrote:
On Fri, 22 Sep 2006 07:27:18 +0000 (GMT) Holger Kiehl <[EMAIL PROTECTED]> 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+0x4f4/0x514Is 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 searched the list, which I should have done before asking (I was not sure if this was due to the e1000) and found this http://www.ussg.iu.edu/hypermail/linux/kernel/0608.0/0942.html discusion from 3rd August. As a summary I read that people are trying to find a solution, in the meantime one should set /proc/sys/vm/min_free_kbytes to 65000 or higher, to ensure that the driver gets enough unfragmented memory. Holger - To unsubscribe from this list: send the line "unsubscribe netdev" in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html
