[PATCH] mm,numa,THP: initialize hstate for THP page size

[Rik van Riel <riel@redhat.com>]

When hugetlbfs is started with a non-default page size, it is
possible that no hstate is initialized for the page sized used
by transparent huge pages.

This causes copy_huge_page to crash on a null pointer. Make
sure we always have an hpage initialized for the page sized
used by THP.

Signed-off-by: Rik van Riel <riel@redhat.com>
Reported-by: Chao Yang <chayang@redhat.com>
---
 mm/huge_memory.c | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/mm/huge_memory.c b/mm/huge_memory.c
index 5749bcf..583e9d3 100644
--- a/mm/huge_memory.c
+++ b/mm/huge_memory.c
@@ -624,6 +624,13 @@ static int __init hugepage_init(void)
 		return -EINVAL;
 	}
 
+	/*
+	 * Make sure an hstate is initialized for our page size,
+	 * even if hugetlbfs is using a non-default page size.
+	 */
+	if (!size_to_hstate(PMD_PAGE_SIZE))
+		hugetlb_add_hstate(HUGETLB_PAGE_ORDER);
+
 	err = hugepage_init_sysfs(&hugepage_kobj);
 	if (err)
 		return err;


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