From mboxrd@z Thu Jan  1 00:00:00 1970
From: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Subject: Re: SLUB allocation error on 3.0.3 / 4.1.1
Date: Mon, 12 Sep 2011 16:17:40 -0400
Message-ID: <20110912201740.GB11900@oracle.com>
References: <4E6E62E8.4050400@gt.net>
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> total_memory           : 98294
> free_memory            : 36580
> free_cpus              : 0
> xen_major              : 4
> xen_minor              : 1
> xen_extra              : .1
> xen_caps               : xen-3.0-x86_64 xen-3.0-x86_32p
> hvm-3.0-x86_32 hvm-3.0-x86_32p hvm-3.0-x86_64
> xen_scheduler          : credit
> xen_pagesize           : 4096
> platform_params        : virt_start=0xffff800000000000
> xen_changeset          : unavailable
> xen_commandline        : console=com1,com2,vga com1=115200,8n1
> com2=115200,8n1 dom0_mem=1024M dom0_max_vcpus=1 dom0_vcpus_pin=true
> cc_compiler            : gcc version 4.3.4 (Gentoo 4.3.4 p1.1, pie-10.1.5)
> cc_compile_by          : root
> cc_compile_domain      : nmsrv.com
> cc_compile_date        : Mon Aug 22 11:28:50 PDT 2011
> xend_config_format     : 4
> 
> Seeing this on multiple dom0's which are all running identical
> hardware (Supermicro X8DTT w/ Intel 82574L gige). Dom0's are limited
> to 1gb (dom0_mem=1024M dom0_max_vcpus=1 dom0_vcpus_pin=true)
> although they don't go above 250mb used.
> 
> Not sure if this is a xen bug, network driver issue or something else?

It is a Linux kernel bug. It does not respect the dom0_mem=max:X argument
so you end up with 98GB of pagetables in Dom0 and you can't allocate
enough memory for your normal drivers (since most of the memory is used
for your non-used pagetables).

The workaround is to put in your Linux command-line: "mem=1GB"
(and keep the dom0_mem=..) arguments.

A patch in 3.0.4 (or 3.0.5) should soon surface which will fix this.