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Date:   Sat, 25 Jun 2022 16:07:30 +0200
From:   Greg KH <gregkh@linuxfoundation.org>
To:     Huacai Chen <chenhuacai@kernel.org>
Cc:     Muchun Song <songmuchun@bytedance.com>,
        Feiyang Chen <chris.chenfeiyang@gmail.com>,
        Andrew Morton <akpm@linux-foundation.org>,
        Matthew Wilcox <willy@infradead.org>,
        Vlastimil Babka <vbabka@suse.cz>,
        Feiyang Chen <chenfeiyang@loongson.cn>,
        loongarch@lists.linux.dev, LKML <linux-kernel@vger.kernel.org>,
        linux- stable <stable@vger.kernel.org>
Subject: Re: [External] Re: [PATCH] page-flags.h: Fix a missing header
 include of static_keys.h
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On Sat, Jun 25, 2022 at 10:00:43PM +0800, Huacai Chen wrote:
> Hi, Muchun,
> 
> On Sat, Jun 25, 2022 at 7:17 PM Muchun Song <songmuchun@bytedance.com> wrote:
> >
> > On Sat, Jun 25, 2022 at 5:04 PM Huacai Chen <chenhuacai@kernel.org> wrote:
> > >
> > > Hi, Muchun,
> > >
> > > On Sat, Jun 25, 2022 at 4:50 PM Muchun Song <songmuchun@bytedance.com> wrote:
> > > >
> > > > On Sat, Jun 25, 2022 at 4:04 PM Feiyang Chen
> > > > <chris.chenfeiyang@gmail.com> wrote:
> > > > >
> > > > > The page-flags.h header relies on static keys since commit
> > > > > a6b40850c442bf ("mm: hugetlb: replace hugetlb_free_vmemmap_enabled
> > > > > with a static_key"), so make sure to include the header to avoid
> > > > > compilation errors.
> > > > >
> > > > > Fixes: a6b40850c442bf ("mm: hugetlb: replace hugetlb_free_vmemmap_enabled with a static_key")
> > > > > Cc: stable@vger.kernel.org
> > > > > Signed-off-by: Feiyang Chen <chenfeiyang@loongson.cn>
> > > > > ---
> > > > >  include/linux/page-flags.h | 1 +
> > > > >  1 file changed, 1 insertion(+)
> > > > >
> > > > > diff --git a/include/linux/page-flags.h b/include/linux/page-flags.h
> > > > > index e66f7aa3191d..147b336c7a35 100644
> > > > > --- a/include/linux/page-flags.h
> > > > > +++ b/include/linux/page-flags.h
> > > > > @@ -11,6 +11,7 @@
> > > > >  #include <linux/mmdebug.h>
> > > > >  #ifndef __GENERATING_BOUNDS_H
> > > > >  #include <linux/mm_types.h>
> > > > > +#include <linux/static_key.h>
> > > >
> > > > I did not include this. The change makes sense to me. But I am
> > > > curious what configs cause the compiling error. Would you mind
> > > > sharing the config with us?
> > > We found this problem when we add
> > > ARCH_WANT_HUGETLB_PAGE_OPTIMIZE_VMEMMAP to LoongArch. Since this isn't
> >
> > Good news to me. I would love to hear more archs support for HVO (HugeTLB
> > Vmemmap Optimization).
> >
> > > upstream yet, we cannot give such a config now (the default config of
> > > X86 and ARM64 is just OK).
> >
> > All right. In this case, the "Cc: stable@vger.kernel.org" is unnecessary.
> Maybe make randconfig will have problems on X86/ARM64, so backporting
> to 5.18 seems reasonable.

Unless it is proven to be needed, there is no need to backport it.

thanks,

greg k-h