* [PATCH] mm: Mark create_huge_pmd() inline to prevent build failure
@ 2017-07-12 6:57 Geert Uytterhoeven
2017-07-12 7:22 ` Arnd Bergmann
2017-07-13 0:29 ` Dan Williams
0 siblings, 2 replies; 8+ messages in thread
From: Geert Uytterhoeven @ 2017-07-12 6:57 UTC (permalink / raw)
To: Dan Williams, Andrew Morton
Cc: Arnd Bergmann, linux-mm, linux-kernel, Geert Uytterhoeven
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)
{
if (vma_is_anonymous(vmf->vma))
return do_huge_pmd_anonymous_page(vmf);
--
2.7.4
--
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>
^ permalink raw reply related [flat|nested] 8+ messages in thread
* Re: [PATCH] mm: Mark create_huge_pmd() inline to prevent build failure
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
2017-07-13 0:29 ` Dan Williams
1 sibling, 1 reply; 8+ messages in thread
From: Arnd Bergmann @ 2017-07-12 7:22 UTC (permalink / raw)
To: Geert Uytterhoeven
Cc: Dan Williams, Andrew Morton, Linux-MM, Linux Kernel Mailing List
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
--
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>
^ permalink raw reply [flat|nested] 8+ messages in thread
* Re: [PATCH] mm: Mark create_huge_pmd() inline to prevent build failure
2017-07-12 7:22 ` Arnd Bergmann
@ 2017-07-12 7:37 ` Geert Uytterhoeven
2017-07-12 8:00 ` Arnd Bergmann
0 siblings, 1 reply; 8+ messages in thread
From: Geert Uytterhoeven @ 2017-07-12 7:37 UTC (permalink / raw)
To: Arnd Bergmann
Cc: Dan Williams, Andrew Morton, Linux-MM, Linux Kernel Mailing List
Hi Arnd,
On Wed, Jul 12, 2017 at 9:22 AM, Arnd Bergmann <arnd@arndb.de> wrote:
> 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>
Thanks!
>> ---
>> 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.
You did mention seeing it with mips-gcc-4.1 in the thread "[RFC] minimum gcc
version for kernel: raise to gcc-4.3 or 4.6?", but didn't provide any further
details. Finally I started seeing it myself for m68k ;-)
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>
^ permalink raw reply [flat|nested] 8+ messages in thread
* Re: [PATCH] mm: Mark create_huge_pmd() inline to prevent build failure
2017-07-12 7:37 ` Geert Uytterhoeven
@ 2017-07-12 8:00 ` Arnd Bergmann
0 siblings, 0 replies; 8+ messages in thread
From: Arnd Bergmann @ 2017-07-12 8:00 UTC (permalink / raw)
To: Geert Uytterhoeven
Cc: Dan Williams, Andrew Morton, Linux-MM, Linux Kernel Mailing List
On Wed, Jul 12, 2017 at 9:37 AM, Geert Uytterhoeven
<geert@linux-m68k.org> wrote:
> You did mention seeing it with mips-gcc-4.1 in the thread "[RFC] minimum gcc
> version for kernel: raise to gcc-4.3 or 4.6?", but didn't provide any further
> details. Finally I started seeing it myself for m68k ;-)
Ah right, I misremembered that then.
Arnd
--
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>
^ permalink raw reply [flat|nested] 8+ messages in thread
* Re: [PATCH] mm: Mark create_huge_pmd() inline to prevent build failure
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
@ 2017-07-13 0:29 ` Dan Williams
2017-07-13 4:01 ` Dan Williams
2017-07-13 7:04 ` Geert Uytterhoeven
1 sibling, 2 replies; 8+ messages in thread
From: Dan Williams @ 2017-07-13 0:29 UTC (permalink / raw)
To: Geert Uytterhoeven; +Cc: Andrew Morton, Arnd Bergmann, Linux MM, linux-kernel
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?
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.
--
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>
^ permalink raw reply [flat|nested] 8+ messages in thread
* Re: [PATCH] mm: Mark create_huge_pmd() inline to prevent build failure
2017-07-13 0:29 ` Dan Williams
@ 2017-07-13 4:01 ` Dan Williams
2017-07-13 7:04 ` Geert Uytterhoeven
1 sibling, 0 replies; 8+ messages in thread
From: Dan Williams @ 2017-07-13 4:01 UTC (permalink / raw)
To: Geert Uytterhoeven; +Cc: Andrew Morton, Arnd Bergmann, Linux MM, linux-kernel
On Wed, Jul 12, 2017 at 5:29 PM, 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
...of course I meant *compiler* instead of 'kernel' here
> to ignore the inline
> hint? If it must be inlined to avoid compile errors then it should be
> __always_inline, right?
>
> 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.
>
--
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>
^ permalink raw reply [flat|nested] 8+ messages in thread
* Re: [PATCH] mm: Mark create_huge_pmd() inline to prevent build failure
2017-07-13 0:29 ` Dan Williams
2017-07-13 4:01 ` Dan Williams
@ 2017-07-13 7:04 ` Geert Uytterhoeven
2017-07-13 7:49 ` Dan Williams
1 sibling, 1 reply; 8+ messages in thread
From: Geert Uytterhoeven @ 2017-07-13 7:04 UTC (permalink / raw)
To: Dan Williams; +Cc: Andrew Morton, Arnd Bergmann, Linux MM, linux-kernel
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>
^ permalink raw reply [flat|nested] 8+ messages in thread
* Re: [PATCH] mm: Mark create_huge_pmd() inline to prevent build failure
2017-07-13 7:04 ` Geert Uytterhoeven
@ 2017-07-13 7:49 ` Dan Williams
0 siblings, 0 replies; 8+ messages in thread
From: Dan Williams @ 2017-07-13 7:49 UTC (permalink / raw)
To: Geert Uytterhoeven; +Cc: Andrew Morton, Arnd Bergmann, Linux MM, linux-kernel
On Thu, Jul 13, 2017 at 12:04 AM, Geert Uytterhoeven
<geert@linux-m68k.org> wrote:
> 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
Ah, ok.
Acked-by: Dan Williams <dan.j.williams@intel.com>
--
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>
^ permalink raw reply [flat|nested] 8+ messages in thread
end of thread, other threads:[~2017-07-13 7:50 UTC | newest]
Thread overview: 8+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
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
2017-07-13 7:49 ` Dan Williams
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).