From: Geert Uytterhoeven <geert@linux-m68k.org>
To: Dan Williams <dan.j.williams@intel.com>
Cc: Andrew Morton <akpm@linux-foundation.org>,
Arnd Bergmann <arnd@arndb.de>, Linux MM <linux-mm@kvack.org>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH] mm: Mark create_huge_pmd() inline to prevent build failure
Date: Thu, 13 Jul 2017 09:04:42 +0200 [thread overview]
Message-ID: <CAMuHMdWFz5cFngxuYYNtuoRd-=S_4pNybxQ2c-zJsP=SGk5+sQ@mail.gmail.com> (raw)
In-Reply-To: <CAPcyv4jpBRF=pC6fuHeWC0mVKBbvkPRRGGTdB0H=qmoveBTLbQ@mail.gmail.com>
Hi Dan,
On Thu, Jul 13, 2017 at 2:29 AM, Dan Williams <dan.j.williams@intel.com> wrote:
> On Tue, Jul 11, 2017 at 11:57 PM, 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>
>> ---
>> Interestingly, create_huge_pmd() is emitted in the assembler output, but
>> never called.
>> ---
>> mm/memory.c | 2 +-
>> 1 file changed, 1 insertion(+), 1 deletion(-)
>>
>> diff --git a/mm/memory.c b/mm/memory.c
>> index cbb57194687e393a..0e517be91a89e162 100644
>> --- a/mm/memory.c
>> +++ b/mm/memory.c
>> @@ -3591,7 +3591,7 @@ static int do_numa_page(struct vm_fault *vmf)
>> return 0;
>> }
>>
>> -static int create_huge_pmd(struct vm_fault *vmf)
>> +static inline int create_huge_pmd(struct vm_fault *vmf)
>> {
>
> This seems fragile, what if the kernel decides to ignore the inline
> hint? If it must be inlined to avoid compile errors then it should be
> __always_inline, right?
With gcc-4, "inline" is already #define'd to
#define inline inline __attribute__((always_inline,unused)) notrace
> I also wonder if it's enough to just specify __always_inline to
> transparent_hugepage_enabled(), i.e. in case the compiler is making an
> uninlined copy of transparent_hugepage_enabled() in mm/memory.c.
Hence the answer is no.
Gr{oetje,eeting}s,
Geert
--
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@linux-m68k.org
In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
-- Linus Torvalds
--
To unsubscribe, send a message with 'unsubscribe linux-mm' in
the body to majordomo@kvack.org. For more info on Linux MM,
see: http://www.linux-mm.org/ .
Don't email: <a href=mailto:"dont@kvack.org"> email@kvack.org </a>
next prev parent reply other threads:[~2017-07-13 7:04 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-07-12 6:57 [PATCH] mm: Mark create_huge_pmd() inline to prevent build failure Geert Uytterhoeven
2017-07-12 7:22 ` Arnd Bergmann
2017-07-12 7:37 ` Geert Uytterhoeven
2017-07-12 8:00 ` Arnd Bergmann
2017-07-13 0:29 ` Dan Williams
2017-07-13 4:01 ` Dan Williams
2017-07-13 7:04 ` Geert Uytterhoeven [this message]
2017-07-13 7:49 ` Dan Williams
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to='CAMuHMdWFz5cFngxuYYNtuoRd-=S_4pNybxQ2c-zJsP=SGk5+sQ@mail.gmail.com' \
--to=geert@linux-m68k.org \
--cc=akpm@linux-foundation.org \
--cc=arnd@arndb.de \
--cc=dan.j.williams@intel.com \
--cc=linux-kernel@vger.kernel.org \
--cc=linux-mm@kvack.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).