Hi,=20
I have just had a quite unexpected 'low memory situation'...
This is a AMD64 machine with 2 gig memory, running 64 bit userland.
Kernel: 2.6.23-rc3-git10, updating to -rc5-* as soon as i can.

I'm using SLUB:s
To me, this looks odd... I thought that any cached memory would be

reclamed but it was always full.
Ideas?
One example from dmesg:

swapper: page allocation failure. order:1, mode:0x4020
Call Trace:

 <IRQ>  [<ffffffff8026c7ef>] __alloc_pages+0x30f/0x330

 [<ffffffff8028a0a1>] __slab_alloc+0x141/0x590

 [<ffffffff805a5937>] __netdev_alloc_skb+0x17/0x40

 [<ffffffff805a5937>] __netdev_alloc_skb+0x17/0x40

 [<ffffffff8028b470>] __kmalloc_track_caller+0xa0/0xc0

 [<ffffffff805a4b3f>] __alloc_skb+0x6f/0x150

 [<ffffffff805a5937>] __netdev_alloc_skb+0x17/0x40

 [<ffffffff88010945>] :sky2:sky2_rx_alloc+0x25/0xf0

 [<ffffffff88013b0c>] :sky2:sky2_poll+0x6dc/0xcf0

 [<ffffffff805e5f60>] tcp_delack_timer+0x0/0x210

 [<ffffffff805ac38a>] net_rx_action+0x8a/0x140

 [<ffffffff80242ac9>] __do_softirq+0x69/0xe0

 [<ffffffff8020cd9c>] call_softirq+0x1c/0x30

 [<ffffffff8020eb75>] do_softirq+0x35/0x90

 [<ffffffff8020ede0>] do_IRQ+0x80/0x100

 [<ffffffff8020ad00>] default_idle+0x0/0x40

 [<ffffffff8020c121>] ret_from_intr+0x0/0xa

 <EOI>  [<ffffffff8020ad29>] default_idle+0x29/0x40

 [<ffffffff8020ade1>] cpu_idle+0xa1/0xf0
Mem-info:

DMA per-cpu:

CPU    0: Hot: hi:    0, btch:   1 usd:   0   Cold: hi:    0, btch:   1

usd:   0

CPU    1: Hot: hi:    0, btch:   1 usd:   0   Cold: hi:    0, btch:   1

usd:   0

DMA32 per-cpu:

CPU    0: Hot: hi:  186, btch:  31 usd: 163   Cold: hi:   62, btch:  15

usd:  56

CPU    1: Hot: hi:  186, btch:  31 usd:  33   Cold: hi:   62, btch:  15

usd:  60

Active:348343 inactive:122950 dirty:13504 writeback:0 unstable:0

 free:2665 slab:21427 mapped:243884 pagetables:4816 bounce:0

DMA free:8020kB min:20kB low:24kB high:28kB active:1...
[ message continues ]

An order-1 GFP_ATOMIC allocation can fail, and networking should recover

from it.
If this is happening a lot then someting might have been broken.  Do you

have reason to believe that the frequency of this happening has inreased?

-

Well, this isn't only networking, It started with all the apps running

and ended up with a pretty basic desktop with almost nothing running...

(due to continued freezes that caused me to shut down more and more
I have never, to my knowledge, had this happen before...=20
I just happened to start a few downloads with rtorrent and watched the

machine slow down to a crawl... All this with over a gig in cache.
The machine was actually deadlocked for almost a minute at one time.
Top memory usage:

  PID USER      PR  NI  VIRT  RES  SHR S %CPU %MEM    TIME+  COMMAND       =

          =20

 2395 pomac     20   0  440m 289m 238m S    2 14.4  32:56.54 rtorrent

21647 root      20   0  203m 120m  10m S    1  6.0 569:45.31 X             =

          =20

 2351 pomac     20   0  170m 111m  53m S    0  5.5  15:43.66 rtorrent      =

   =20
At peak time, one of the rtorrent processes consumed more, but i still

had 1.x gig as cache, which imho should have been reclaimed.
vmstat now:

procs -----------memory---------- ---swap-- -----io---- -system-- ----cpu--=

--

 r  b   swpd   free   buff  cache   si   so    bi    bo   in   cs us sy id =

wa

 0  0 365204  16628  30644 1445316    2    1   362    92   18   21  4  2 91=

  3
PS. I have a dmesg dump from the incident, it's not long enough to

contain all but it could be seen as a snapshot...

DS.
--=20

Ian Kumlien <pomac () vapor ! com> -- http://pomac.netswarm.net