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Re: [PATCH] mm: Mark create_huge_pmd() inline to prevent build failure

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On Wed, Jul 12, 2017 at 8:57 AM, Geert Uytterhoeven
<geert@linux-m68k.org> wrote:
>
> With gcc 4.1.2:
>
>     mm/memory.o: In function `create_huge_pmd':
>     memory.c:(.text+0x93e): undefined reference to `do_huge_pmd_anonymous_page'
>
> Converting transparent_hugepage_enabled() from a macro to a static
> inline function reduced the ability of the compiler to remove unused
> code.
>
> Fix this by marking create_huge_pmd() inline.
>
> Fixes: 16981d763501c0e0 ("mm: improve readability of transparent_hugepage_enabled()")
> Signed-off-by: Geert Uytterhoeven <geert@linux-m68k.org>

Acked-by: Arnd Bergmann <arnd@arndb.de>

> ---
> Interestingly, create_huge_pmd() is emitted in the assembler output, but
> never called.

I've never seen this before either. I know that early gcc-4 compilers
would do this
when a function is referenced from an unused function pointer, but not with
a compile-time constant evaluation. I guess that transparent_hugepage_enabled
is just slightly more complex than it gcc-4.1 can handle here.

       Arnd

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Thread

[PATCH] mm: Mark create_huge_pmd() inline to prevent build failure Geert Uytterhoeven <geert@linux-m68k.org> - 2017-07-12 09:00 +0200
  Re: [PATCH] mm: Mark create_huge_pmd() inline to prevent build failure Arnd Bergmann <arnd@arndb.de> - 2017-07-12 09:30 +0200
    Re: [PATCH] mm: Mark create_huge_pmd() inline to prevent build failure Geert Uytterhoeven <geert@linux-m68k.org> - 2017-07-12 09:40 +0200
      Re: [PATCH] mm: Mark create_huge_pmd() inline to prevent build failure Arnd Bergmann <arnd@arndb.de> - 2017-07-12 10:10 +0200
  Re: [PATCH] mm: Mark create_huge_pmd() inline to prevent build failure Dan Williams <dan.j.williams@intel.com> - 2017-07-13 02:30 +0200
    Re: [PATCH] mm: Mark create_huge_pmd() inline to prevent build failure Dan Williams <dan.j.williams@intel.com> - 2017-07-13 06:10 +0200
    Re: [PATCH] mm: Mark create_huge_pmd() inline to prevent build failure Geert Uytterhoeven <geert@linux-m68k.org> - 2017-07-13 09:10 +0200
      Re: [PATCH] mm: Mark create_huge_pmd() inline to prevent build failure Dan Williams <dan.j.williams@intel.com> - 2017-07-13 10:00 +0200

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