Re: page allocation failures with 2.6.5 on s390

[Andrew Morton]

Bastian Blank <bastian@xxxxxxxxxxxx> wrote:
>
> Today I see the following error message in the logs of two machines
> with 2.6.5 on s390, both 31 and 64 bit.
> 
> | swapper: page allocation failure. order:2, mode:0x20
> | 0072d8f0 00028b18 00405490 80028bbc 80028dac 0072d868 00392f00 0039068a
> |        00000002 00000001 0039a400 0000001a
> | Call Trace:
> |  [<0000000000049d30>] __alloc_pages+0x318/0x35c
> |  [<0000000000049dbe>] __get_free_pages+0x4a/0x78
> |  [<000000000004d838>] cache_grow+0xe0/0x39c
> |  [<000000000004dcc0>] cache_alloc_refill+0x1cc/0x2d8
> |  [<000000000004e1f2>] __kmalloc+0xaa/0xb8
> |  [<000000000023e810>] alloc_skb+0x5c/0xe4
> |  [<00000000002080ca>] qeth_read_in_buffer+0xd16/0xda0
> |  [<0000000000212e22>] qeth_qdio_input_handler+0x42a/0x57c
> |  [<00000000001de17c>] qdio_handler+0xad4/0x10f4
> |  [<00000000001d46da>] ccw_device_call_handler+0x8a/0x94
> |  [<00000000001d3922>] ccw_device_irq+0x7a/0xb4
> |  [<00000000001d42de>] io_subchannel_irq+0x7e/0xc4
> |  [<00000000001cfcd2>] do_IRQ+0x18a/0x1b0
> |  [<0000000000020072>] io_return+0x0/0x10

This is pretty much unavoidable - the kernel is looking for four
physically-contiguous free pages at interrupt time, and there aren't any.

You can reduce its frequency by increasing /proc/sys/vm/min_free_kbytes.

The best fix would be to alter the driver to use order-0 pages if that's
possible.

> It causes a lot of state-D processes on one machine.

This should not happen.  If it happens again, try to capture an all-task
backtrace into the logs with

	echo t > /proc/sysrq-trigger


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