linux-kernel - Re: [PATCH V12 4/4] LoongArch: Enable ARCH_WANT_HUGETLB_PAGE_OPTIMIZE

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Date:   Fri, 21 Oct 2022 22:08:28 +0800
From:   Huacai Chen <chenhuacai@...nel.org>
To:     Philippe Mathieu-Daudé <philmd@...aro.org>
Cc:     Huacai Chen <chenhuacai@...ngson.cn>,
        Arnd Bergmann <arnd@...db.de>,
        Thomas Bogendoerfer <tsbogend@...ha.franken.de>,
        Dave Hansen <dave.hansen@...ux.intel.com>,
        Andy Lutomirski <luto@...nel.org>,
        Peter Zijlstra <peterz@...radead.org>,
        Catalin Marinas <catalin.marinas@....com>,
        Will Deacon <will@...nel.org>,
        Dinh Nguyen <dinguyen@...nel.org>, loongarch@...ts.linux.dev,
        linux-arch@...r.kernel.org, Xuefeng Li <lixuefeng@...ngson.cn>,
        Guo Ren <guoren@...nel.org>, Xuerui Wang <kernel@...0n.name>,
        Jiaxun Yang <jiaxun.yang@...goat.com>,
        Andrew Morton <akpm@...ux-foundation.org>, linux-mm@...ck.org,
        linux-mips@...r.kernel.org, linux-kernel@...r.kernel.org,
        linux-arm-kernel@...ts.infradead.org,
        Feiyang Chen <chenfeiyang@...ngson.cn>
Subject: Re: [PATCH V12 4/4] LoongArch: Enable ARCH_WANT_HUGETLB_PAGE_OPTIMIZE_VMEMMAP

Hi, Philippe,

On Fri, Oct 21, 2022 at 6:16 PM Philippe Mathieu-Daudé
<philmd@...aro.org> wrote:
>
> On 20/10/22 09:23, Huacai Chen wrote:
> > From: Feiyang Chen <chenfeiyang@...ngson.cn>
> >
> > 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/
>
> s/should/have to/
Thanks, I will change it.

>
> > static_key.h in page-flags.h.
>
> This looks like 2 different changes in a single patch.. The first is a
> generic "fix missing include" and the second is LoongArch specific.
The static_key.h inclusion is also LoongArch-specific, implicitly. X86
and ARM64 have no build errors without this inclusion, because they
include static_key.h from their arch-specific core headers. Once
before I have sent a separate patch to "fix missing include", but Greg
said that "don't fix unless you have a real problem". :)

Huacai

>
> Splitting in 2 would ease backport cherry-picks.
>
> > 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: Feiyang Chen <chenfeiyang@...ngson.cn>
> > Signed-off-by: Huacai Chen <chenhuacai@...ngson.cn>
> > ---
> >   arch/loongarch/Kconfig     | 1 +
> >   include/linux/page-flags.h | 1 +
> >   2 files changed, 2 insertions(+)
> >
> > diff --git a/arch/loongarch/Kconfig b/arch/loongarch/Kconfig
> > index 6f7fa0c0ca08..0a6ef613124c 100644
> > --- a/arch/loongarch/Kconfig
> > +++ b/arch/loongarch/Kconfig
> > @@ -52,6 +52,7 @@ config LOONGARCH
> >       select ARCH_USE_QUEUED_RWLOCKS
> >       select ARCH_USE_QUEUED_SPINLOCKS
> >       select ARCH_WANT_DEFAULT_TOPDOWN_MMAP_LAYOUT
> > +     select ARCH_WANT_HUGETLB_PAGE_OPTIMIZE_VMEMMAP
> >       select ARCH_WANT_LD_ORPHAN_WARN
> >       select ARCH_WANTS_NO_INSTR
> >       select BUILDTIME_TABLE_SORT
> > diff --git a/include/linux/page-flags.h b/include/linux/page-flags.h
> > index 0b0ae5084e60..1aafdc73e399 100644
> > --- a/include/linux/page-flags.h
> > +++ b/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>
>
> Preferably splitting in 2 distinct patches (for each):
>
> Reviewed-by: Philippe Mathieu-Daudé <philmd@...aro.org>
>
>