Re: iwl3945: order 5 allocation during ifconfig up; vm problem?

On Tue, Sep 11, 2012 at 04:25:36PM -0700, Andrew Morton wrote:

On Mon, 10 Sep 2012 13:11:13 +0200
Pavel Machek [off-list ref] wrote:

quoted

On Sun 2012-09-09 15:40:55, David Rientjes wrote:

quoted

On Sun, 9 Sep 2012, Pavel Machek wrote:

quoted

On 3.6.0-rc2+, I tried to turn on the wireless, but got

root@amd:~# ifconfig wlan0 10.0.0.6 up
SIOCSIFFLAGS: Cannot allocate memory
SIOCSIFFLAGS: Cannot allocate memory
root@amd:~# 

It looks like it uses "a bit too big" allocations to allocate
firmware...? Order five allocation....

Hmm... then I did "echo 3  > /proc/sys/vm/drop_caches" and now the
network works. Is it VM problem that it failed to allocate memory when
it was freeable?

Do you have CONFIG_COMPACTION enabled?

Yes:

pavel@amd:/data/l/linux-good$ zgrep CONFIG_COMPACTION /proc/config.gz 
CONFIG_COMPACTION=y

Asking for a 256k allocation is pretty crazy - this is an operating
system kernel, not a userspace application.

I'm wondering if this is due to a recent change, but I'm having trouble
working out where the allocation call site is.

iwlwifi/iwlegacy do such kind of allocation for ages, since iwlwifi driver
inclusion in 2.6.24 (however firmware was smaller then).

I can fix that in iwlegacy similar as Johannes did it in iwlwifi, but this
actually seems to be allocator regression. We use GFP_KERNEL allocation,
kernel can wait for free memory and/or swap out pages, I do not understand
why this fail.

Stanislaw