From 55878e88c59221c3187e1c24ec3b15eb79c374c0 Mon Sep 17 00:00:00 2001 From: Cody P Schafer Date: Wed, 3 Jul 2013 15:04:44 -0700 Subject: sparsemem: add BUILD_BUG_ON when sizeof mem_section is non-power-of-2 Instead of leaving a hidden trap for the next person who comes along and wants to add something to mem_section, add a big fat warning about it needing to be a power-of-2, and insert a BUILD_BUG_ON() in sparse_init() to catch mistakes. Right now non-power-of-2 mem_sections cause a number of WARNs at boot (which don't clearly point to the size of mem_section as an issue), but the system limps on (temporarily, at least). This is based upon Dave Hansen's earlier RFC where he ran into the same issue: "sparsemem: fix boot when SECTIONS_PER_ROOT is not power-of-2" http://lkml.indiana.edu/hypermail/linux/kernel/1205.2/03077.html Signed-off-by: Cody P Schafer Acked-by: Dave Hansen Cc: Jiang Liu Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- mm/sparse.c | 3 +++ 1 file changed, 3 insertions(+) (limited to 'mm') diff --git a/mm/sparse.c b/mm/sparse.c index 1c91f0d3f6ab..3194ec414728 100644 --- a/mm/sparse.c +++ b/mm/sparse.c @@ -481,6 +481,9 @@ void __init sparse_init(void) struct page **map_map; #endif + /* see include/linux/mmzone.h 'struct mem_section' definition */ + BUILD_BUG_ON(!is_power_of_2(sizeof(struct mem_section))); + /* Setup pageblock_order for HUGETLB_PAGE_SIZE_VARIABLE */ set_pageblock_order(); -- cgit v1.2.3