From: Mel Gorman <mel@csn.ul.ie>
Date: Thu, 3 Jul 2008 04:27:51 +0000 (+0100)
Subject: Do not overwrite nr_zones on !NUMA when initialising zlcache_ptr
X-Git-Tag: v2.6.26-rc9~67
X-Git-Url: http://git.openpandora.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=494de90098784b8e2797598cefdd34188884ec2e;p=pandora-kernel.git

Do not overwrite nr_zones on !NUMA when initialising zlcache_ptr

The non-NUMA case of build_zonelist_cache() would initialize the
zlcache_ptr for both node_zonelists[] to NULL.

Which is problematic, since non-NUMA only has a single node_zonelists[]
entry, and trying to zero the non-existent second one just overwrote the
nr_zones field instead.

As kswapd uses this value to determine what reclaim work is necessary,
the result is that kswapd never reclaims.  This causes processes to
stall frequently in low-memory situations as they always direct reclaim.
This patch initialises zlcache_ptr correctly.

Signed-off-by: Mel Gorman <mel@csn.ul.ie>
Tested-by: Dan Williams <dan.j.williams@intel.com>
[ Simplified patch a bit ]
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
---

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