[PATCH] mm/hugetlb: Fix build with !ARCH_WANT_HUGE_PMD_SHARE

[Peter Xu <peterx@redhat.com>]

want_pmd_share() is undefined with !ARCH_WANT_HUGE_PMD_SHARE since it's put
by accident into a "#ifdef ARCH_WANT_HUGE_PMD_SHARE" block.  Moving it out
won't work either since vma_shareable() is only defined within the block.
Define it for !ARCH_WANT_HUGE_PMD_SHARE instead.

Fixes: 5b109cc1cdcc ("hugetlb/userfaultfd: forbid huge pmd sharing when uffd enabled")
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Mike Kravetz <mike.kravetz@oracle.com>
Cc: Axel Rasmussen <axelrasmussen@google.com>
Reported-by: Naresh Kamboju <naresh.kamboju@linaro.org>
Tested-by: Naresh Kamboju <naresh.kamboju@linaro.org>
Signed-off-by: Peter Xu <peterx@redhat.com>
---
 mm/hugetlb.c | 8 +++++---
 1 file changed, 5 insertions(+), 3 deletions(-)

diff --git a/mm/hugetlb.c b/mm/hugetlb.c
index d58f1456fe27..8dda7e034477 100644
--- a/mm/hugetlb.c
+++ b/mm/hugetlb.c
@@ -5469,9 +5469,6 @@ static bool vma_shareable(struct vm_area_struct *vma, unsigned long addr)
 
 bool want_pmd_share(struct vm_area_struct *vma, unsigned long addr)
 {
-#ifndef CONFIG_ARCH_WANT_HUGE_PMD_SHARE
-	return false;
-#endif
 #ifdef CONFIG_USERFAULTFD
 	if (uffd_disable_huge_pmd_share(vma))
 		return false;
@@ -5616,6 +5613,11 @@ void adjust_range_if_pmd_sharing_possible(struct vm_area_struct *vma,
 				unsigned long *start, unsigned long *end)
 {
 }
+
+bool want_pmd_share(struct vm_area_struct *vma, unsigned long addr)
+{
+	return false;
+}
 #endif /* CONFIG_ARCH_WANT_HUGE_PMD_SHARE */
 
 #ifdef CONFIG_ARCH_WANT_GENERAL_HUGETLB
-- 
2.26.2