[v3][PATCH 1/2] mm: hugetlbfs: Add VM_BUG_ON()s to catch non-hugetlbfs pages

[Dave Hansen]

From: Dave Hansen <dave.hansen@xxxxxxxxxxxxxxx>

Changes from v2:
 * Removed the VM_BUG_ON() from copy_huge_page() since the
   next patch makes it able to handle non-hugetlbfs pages

--

Dave Jiang reported that he was seeing oopses when running
NUMA systems and default_hugepagesz=1G.  I traced the issue down
to migrate_page_copy() trying to use the same code for hugetlb
pages and transparent hugepages.  It should not have been trying
to pass thp pages in there.

So, add a VM_BUG_ON()s for the next hapless developer that
tries to use page_hstate() on a non-hugetlbfs page.

Signed-off-by: Dave Hansen <dave.hansen@xxxxxxxxxxxxxxx>
Reviewed-by: Naoya Horiguchi <n-horiguchi@xxxxxxxxxxxxx>
Acked-by: Mel Gorman <mgorman@xxxxxxx>

---

 linux.git-davehans/include/linux/hugetlb.h |    1 +
 1 file changed, 1 insertion(+)

diff -puN include/linux/hugetlb.h~bug-not-hugetlbfs-in-copy_huge_page include/linux/hugetlb.h
--- linux.git/include/linux/hugetlb.h~bug-not-hugetlbfs-in-copy_huge_page	2013-11-15 14:44:41.550357120 -0800
+++ linux.git-davehans/include/linux/hugetlb.h	2013-11-15 14:44:41.553357255 -0800
@@ -355,6 +355,7 @@ static inline pte_t arch_make_huge_pte(p
 
 static inline struct hstate *page_hstate(struct page *page)
 {
+	VM_BUG_ON(!PageHuge(page));
 	return size_to_hstate(PAGE_SIZE << compound_order(page));
 }
 
_
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