LoongArch: Enable ARCH_WANT_HUGETLB_PAGE_OPTIMIZE_VMEMMAP

LoongArch inclusion
category: feature
bugzilla: https://gitee.com/openeuler/kernel/issues/I5OHOB

--------------------------------

The feature of minimizing overhead of struct page associated with each
HugeTLB page is implemented on x86_64. However, the infrastructure of
this feature is already there, so just select ARCH_WANT_HUGETLB_PAGE_
OPTIMIZE_VMEMMAP is enough to enable this feature for LoongArch.

To avoid the following build error on LoongArch we should include linux/
static_key.h in page-flags.h.

In file included from ./include/linux/mmzone.h:22,
from ./include/linux/gfp.h:6,
from ./include/linux/mm.h:7,
from arch/loongarch/kernel/asm-offsets.c:9:
./include/linux/page-flags.h:208:1: warning: data definition has no
type or storage class
208 | DECLARE_STATIC_KEY_MAYBE(CONFIG_HUGETLB_PAGE_OPTIMIZE_VMEMMAP_DEFAULT_ON,
| ^~~~~~~~~~~~~~~~~~~~~~~~
./include/linux/page-flags.h:208:1: error: type defaults to 'int' in
declaration of 'DECLARE_STATIC_KEY_MAYBE' [-Werror=implicit-int]
./include/linux/page-flags.h:209:26: warning: parameter names (without
types) in function declaration
209 | hugetlb_optimize_vmemmap_key);
| ^~~~~~~~~~~~~~~~~~~~~~~~~~~~
./include/linux/page-flags.h: In function 'hugetlb_optimize_vmemmap_enabled':
./include/linux/page-flags.h:213:16: error: implicit declaration of
function 'static_branch_maybe' [-Werror=implicit-function-declaration]
213 | return static_branch_maybe(CONFIG_HUGETLB_PAGE_OPTIMIZE_VMEMMAP_DEFAULT_ON,
| ^~~~~~~~~~~~~~~~~~~
./include/linux/page-flags.h:213:36: error:
'CONFIG_HUGETLB_PAGE_OPTIMIZE_VMEMMAP_DEFAULT_ON' undeclared (first
use in this function); did you mean
'CONFIG_HUGETLB_PAGE_OPTIMIZE_VMEMMAP'?
213 | return static_branch_maybe(CONFIG_HUGETLB_PAGE_OPTIMIZE_VMEMMAP_DEFAULT_ON,
| ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
| CONFIG_HUGETLB_PAGE_OPTIMIZE_VMEMMAP
./include/linux/page-flags.h:213:36: note: each undeclared identifier
is reported only once for each function it appears in
./include/linux/page-flags.h:214:37: error:
'hugetlb_optimize_vmemmap_key' undeclared (first use in this
function); did you mean 'hugetlb_optimize_vmemmap_enabled'?
214 | &hugetlb_optimize_vmemmap_key);
| ^~~~~~~~~~~~~~~~~~~~~~~~~~~~
| hugetlb_optimize_vmemmap_enabled
Signed-off-by: NFeiyang Chen <chenfeiyang@loongson.cn>
Signed-off-by: NHuacai Chen <chenhuacai@loongson.cn>

arch/loongarch/Kconfig

@@ -51,6 +51,7 @@ config LOONGARCH
 	select ARCH_USE_CMPXCHG_LOCKREF
 	select ARCH_USE_QUEUED_RWLOCKS
 	select ARCH_WANT_DEFAULT_TOPDOWN_MMAP_LAYOUT
+	select ARCH_WANT_HUGETLB_PAGE_OPTIMIZE_VMEMMAP
 	select ARCH_WANTS_NO_INSTR
 	select BUILDTIME_TABLE_SORT
 	select COMMON_CLK

include/linux/page-flags.h

@@ -9,6 +9,7 @@
 #include <linux/types.h>
 #include <linux/bug.h>
 #include <linux/mmdebug.h>
+#include <linux/static_key.h>
 #ifndef __GENERATING_BOUNDS_H
 #include <linux/mm_types.h>
 #include <generated/bounds.h>