From 88fdf75d1bb51d85ba00c466391770056d44bc03 Mon Sep 17 00:00:00 2001 From: Minchan Kim Date: Tue, 31 Jul 2012 16:46:14 -0700 Subject: [PATCH] mm: warn if pg_data_t isn't initialized with zero Warn if memory-hotplug/boot code doesn't initialize pg_data_t with zero when it is allocated. Arch code and memory hotplug already initiailize pg_data_t. So this warning should never happen. I select fields randomly near the beginning, middle and end of pg_data_t for checking. This patch isn't for performance but for removing initialization code which is necessary to add whenever we adds new field to pg_data_t or zone. Firstly, Andrew suggested clearing out of pg_data_t in MM core part but Tejun doesn't like it because in the future, some archs can initialize some fields in arch code and pass them into general MM part so blindly clearing it out in mm core part would be very annoying. Signed-off-by: Minchan Kim Cc: Tejun Heo Cc: Ralf Baechle Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- mm/page_alloc.c | 3 +++ 1 file changed, 3 insertions(+) diff --git a/mm/page_alloc.c b/mm/page_alloc.c index 48aee0f5902f..a6f7576aecae 100644 --- a/mm/page_alloc.c +++ b/mm/page_alloc.c @@ -4515,6 +4515,9 @@ void __paginginit free_area_init_node(int nid, unsigned long *zones_size, { pg_data_t *pgdat = NODE_DATA(nid); + /* pg_data_t should be reset to zero when it's allocated */ + WARN_ON(pgdat->nr_zones || pgdat->node_start_pfn || pgdat->classzone_idx); + pgdat->node_id = nid; pgdat->node_start_pfn = node_start_pfn; calculate_node_totalpages(pgdat, zones_size, zholes_size);