[Utopic workaround] Temporarily reduce KASLR range

[Stefan Bader]

>From 2cd5f1b7735c5efafcb77eaf49d0d6dbf0fea9bf Mon Sep 17 00:00:00 2001
From: Stefan Bader <stefan.bader at canonical.com>
Date: Tue, 26 Aug 2014 12:49:15 +0200
Subject: [PATCH] UBUNTU: SAUCE: (config) Temporarily reduce KASLR range

BugLink: http:/bugs.launchpad.net/bugs/1350522

This regression was indirectly introduced by enabling Kernel
Address Space Location Randomization. On 64bit this changes
the split between kernel and modules which in turn seems to
mess up paravirt Xen guests (and dom0 is PV, too).

The boot visible effect is vmalloc failures which can even cause
crashes (dom0 rather crashes while domU may survive in some undefined
state).

I am still trying to figure out what exactly goes wrong. But for
the mean-time it would allow Utopic dom0 and domU guests to come
up again if we changed the kernel/module split back to 512M/~1.5G
(as it was before).

This will make the randomization less effective (since the kernel
then can only move within the 512M range) but at least those kernels
can be used in EC2 (and set up Xen hosts based on Utopic).

Signed-off-by: Stefan Bader <stefan.bader at canonical.com>
---
 debian.master/config/amd64/config.common.amd64 | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/debian.master/config/amd64/config.common.amd64 b/debian.master/config/amd64/config.common.amd64
index 9e82d9b..753124c 100644
--- a/debian.master/config/amd64/config.common.amd64
+++ b/debian.master/config/amd64/config.common.amd64
@@ -92,7 +92,7 @@ CONFIG_PROBE_EVENTS=y
 # CONFIG_PSTORE_CONSOLE is not set
 CONFIG_PSTORE_RAM=m
 CONFIG_PTP_1588_CLOCK=m
-CONFIG_RANDOMIZE_BASE_MAX_OFFSET=0x40000000
+CONFIG_RANDOMIZE_BASE_MAX_OFFSET=0x20000000
 CONFIG_RCU_CPU_STALL_TIMEOUT=60
 CONFIG_RCU_FANOUT=64
 CONFIG_RCU_FAST_NO_HZ=y
-- 
1.9.1