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Do not overwrite nr_zones on !NUMA when initialising zlcache_ptr

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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>
This commit is contained in:
Mel Gorman 2008-07-03 05:27:51 +01:00 committed by Linus Torvalds
parent c461a97311
commit 494de90098
1 changed files with 0 additions and 1 deletions
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mm/page_alloc.c
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@ -2328,7 +2328,6 @@ static void build_zonelists(pg_data_t *pgdat)
static void build_zonelist_cache(pg_data_t *pgdat)
{
pgdat->node_zonelists[0].zlcache_ptr = NULL;
pgdat->node_zonelists[1].zlcache_ptr = NULL;
}
#endif /* CONFIG_NUMA */