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authorCody P Schafer <cody@linux.vnet.ibm.com>2013-07-04 00:04:44 +0200
committerLinus Torvalds <torvalds@linux-foundation.org>2013-07-04 01:07:40 +0200
commit55878e88c59221c3187e1c24ec3b15eb79c374c0 (patch)
treef0c9a994d63b3fb64dffe6477317db53453b2b61 /mm/sparse.c
parentmm/unicore32: fix stale comment about VALID_PAGE() (diff)
downloadlinux-55878e88c59221c3187e1c24ec3b15eb79c374c0.tar.xz
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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 <cody@linux.vnet.ibm.com> Acked-by: Dave Hansen <dave.hansen@linux.intel.com> Cc: Jiang Liu <liuj97@gmail.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to '')
-rw-r--r--mm/sparse.c3
1 files changed, 3 insertions, 0 deletions
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();