On Tue, Jul 5, 2022 at 4:06 PM Arnd Bergmann <arnd@xxxxxxxx> wrote:
>
> On Tue, Jul 5, 2022 at 9:51 AM Muchun Song <songmuchun@xxxxxxxxxxxxx> wrote:
> >
> > On Tue, Jul 5, 2022 at 2:22 PM Huacai Chen <chenhuacai@xxxxxxxxxx> wrote:
> > >
> > > Hi, Arnd,
> > >
> > > On Mon, Jul 4, 2022 at 8:18 PM Arnd Bergmann <arnd@xxxxxxxx> wrote:
> > > >
> > > > On Mon, Jul 4, 2022 at 1:25 PM Huacai Chen <chenhuacai@xxxxxxxxxxx> wrote:
> > > > > 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
> > > >
> > > > I wonder if page_fixed_fake_head() should be moved out of line to avoid
> > > > this, it's already nontrivial here, and that would avoid the static key
> > > > in a central header.
> > > I have some consideration here. I think both inline function and
> > > static key are instruments to make things faster, in other words,
> > > page_fixed_fake_head() is a performance critical function. If so, it
> > > is not suitable to move it out of line.
> >
> > +1
> >
> > The static key is an optimization when HVO is disabled.
>
> How about splitting up linux/page_flags.h so the static_key header is
> only included
> in those places that use one of the inline functions that depend on it?
>
How about including the static key header in the scope of
CONFIG_HUGETLB_PAGE_OPTIMIZE_VMEMMAP?
diff --git a/include/linux/page-flags.h b/include/linux/page-flags.h
index 465ff35a8c00..4dd005ad43fc 100644
--- a/include/linux/page-flags.h
+++ b/include/linux/page-flags.h
@@ -205,6 +205,8 @@ enum pageflags {
#ifndef __GENERATING_BOUNDS_H
#ifdef CONFIG_HUGETLB_PAGE_OPTIMIZE_VMEMMAP
+#include <linux/static_key.h>
+
DECLARE_STATIC_KEY_FALSE(hugetlb_optimize_vmemmap_key);
/*
