[PATCH] mm/hugetlb: include pagemap.h to fix build error

[SeongJae Park]

Without this, UML build fails as below:

    $ make all compile_commands.json scripts_gdb ARCH=um O=.kunit --jobs=8
    ERROR:root:In file included from ../io_uring/rsrc.c:9:
    ../include/linux/hugetlb.h: In function ‘vma_hugecache_offset’:
    ../include/linux/hugetlb.h:1214:16: error: implicit declaration of function ‘linear_page_index’ [-Wimplicit-function-declaration]
     1214 |         return linear_page_index(vma, address);
          |                ^~~~~~~~~~~~~~~~~

Signed-off-by: SeongJae Park <sj@xxxxxxxxxx>
---
 include/linux/hugetlb.h | 1 +
 1 file changed, 1 insertion(+)

diff --git a/include/linux/hugetlb.h b/include/linux/hugetlb.h
index 3f994f3e839cf..63426bd716839 100644
--- a/include/linux/hugetlb.h
+++ b/include/linux/hugetlb.h
@@ -15,6 +15,7 @@
 #include <linux/gfp.h>
 #include <linux/userfaultfd_k.h>
 #include <linux/nodemask.h>
+#include <linux/pagemap.h>
 
 struct mmu_gather;
 struct node;
-- 
2.47.3