generic gup fixups

generic gup fixups

[Christoph Hellwig]

Hi Andrew,

below two fixups for the generic GUP series, as reported by Guenter.

[PATCH 1/2] sh: stub out pud_page

[Christoph Hellwig]

There wasn't any actual need to add a real pud_page, as pud_huge
always returns false on sh.  Just stub it out to fix the sh3
compile failure.

Fixes: 937b4e1d6471 ("sh: add the missing pud_page definition")
Reported-by: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: Christoph Hellwig <hch@lst.de>
---
 arch/sh/include/asm/pgtable-3level.h | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/arch/sh/include/asm/pgtable-3level.h b/arch/sh/include/asm/pgtable-3level.h
index 3c7ff20f3f94..779260b721ca 100644
--- a/arch/sh/include/asm/pgtable-3level.h
+++ b/arch/sh/include/asm/pgtable-3level.h
@@ -37,7 +37,9 @@ static inline unsigned long pud_page_vaddr(pud_t pud)
 {
 	return pud_val(pud);
 }
-#define pud_page(pud)		pfn_to_page(pud_pfn(pud))
+
+/* only used by the stubbed out hugetlb gup code, should never be called */
+#define pud_page(pud)		NULL
 
 #define pmd_index(address)	(((address) >> PMD_SHIFT) & (PTRS_PER_PMD-1))
 static inline pmd_t *pmd_offset(pud_t *pud, unsigned long address)
-- 
2.20.1

[PATCH 2/2] MIPS: don't select ARCH_HAS_PTE_SPECIAL

[Christoph Hellwig]

MIPS doesn't really have a proper pte_special implementation, just
stubs.  It turns out they were not enough to make get_user_pages_fast
work, so drop the select.  This means get_user_pages_fast won't
actually use the fast path for non-hugepage mappings, so someone who
actually knows about mips page table management should look into
adding real pte_special support.

Fixes: eb9488e58bbc ("MIPS: use the generic get_user_pages_fast code")
Reported-by: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: Christoph Hellwig <hch@lst.de>
---
 arch/mips/Kconfig | 1 -
 1 file changed, 1 deletion(-)

diff --git a/arch/mips/Kconfig b/arch/mips/Kconfig
index b1e42f0e4ed0..7957d3457156 100644
--- a/arch/mips/Kconfig
+++ b/arch/mips/Kconfig
@@ -6,7 +6,6 @@ config MIPS
 	select ARCH_BINFMT_ELF_STATE if MIPS_FP_SUPPORT
 	select ARCH_CLOCKSOURCE_DATA
 	select ARCH_HAS_ELF_RANDOMIZE
-	select ARCH_HAS_PTE_SPECIAL
 	select ARCH_HAS_TICK_BROADCAST if GENERIC_CLOCKEVENTS_BROADCAST
 	select ARCH_HAS_UBSAN_SANITIZE_ALL
 	select ARCH_SUPPORTS_UPROBES
-- 
2.20.1

Re: [PATCH 1/2] sh: stub out pud_page

[Guenter Roeck]

On Mon, Jul 01, 2019 at 05:18:17PM +0200, Christoph Hellwig wrote:
> There wasn't any actual need to add a real pud_page, as pud_huge
> always returns false on sh.  Just stub it out to fix the sh3
> compile failure.
> 
> Fixes: 937b4e1d6471 ("sh: add the missing pud_page definition")
> Reported-by: Guenter Roeck <linux@roeck-us.net>
> Signed-off-by: Christoph Hellwig <hch@lst.de>

Tested-by: Guenter Roeck <linux@roeck-us.net>

> ---
>  arch/sh/include/asm/pgtable-3level.h | 4 +++-
>  1 file changed, 3 insertions(+), 1 deletion(-)
> 
> diff --git a/arch/sh/include/asm/pgtable-3level.h b/arch/sh/include/asm/pgtable-3level.h
> index 3c7ff20f3f94..779260b721ca 100644
> --- a/arch/sh/include/asm/pgtable-3level.h
> +++ b/arch/sh/include/asm/pgtable-3level.h
> @@ -37,7 +37,9 @@ static inline unsigned long pud_page_vaddr(pud_t pud)
>  {
>  	return pud_val(pud);
>  }
> -#define pud_page(pud)		pfn_to_page(pud_pfn(pud))
> +
> +/* only used by the stubbed out hugetlb gup code, should never be called */
> +#define pud_page(pud)		NULL
>  
>  #define pmd_index(address)	(((address) >> PMD_SHIFT) & (PTRS_PER_PMD-1))
>  static inline pmd_t *pmd_offset(pud_t *pud, unsigned long address)
> -- 
> 2.20.1
> 

Re: [PATCH 2/2] MIPS: don't select ARCH_HAS_PTE_SPECIAL

[Guenter Roeck]

On Mon, Jul 01, 2019 at 05:18:18PM +0200, Christoph Hellwig wrote:
> MIPS doesn't really have a proper pte_special implementation, just
> stubs.  It turns out they were not enough to make get_user_pages_fast
> work, so drop the select.  This means get_user_pages_fast won't
> actually use the fast path for non-hugepage mappings, so someone who
> actually knows about mips page table management should look into
> adding real pte_special support.
> 
> Fixes: eb9488e58bbc ("MIPS: use the generic get_user_pages_fast code")
> Reported-by: Guenter Roeck <linux@roeck-us.net>
> Signed-off-by: Christoph Hellwig <hch@lst.de>

Tested-by: Guenter Roeck <linux@roeck-us.net>

> ---
>  arch/mips/Kconfig | 1 -
>  1 file changed, 1 deletion(-)
> 
> diff --git a/arch/mips/Kconfig b/arch/mips/Kconfig
> index b1e42f0e4ed0..7957d3457156 100644
> --- a/arch/mips/Kconfig
> +++ b/arch/mips/Kconfig
> @@ -6,7 +6,6 @@ config MIPS
>  	select ARCH_BINFMT_ELF_STATE if MIPS_FP_SUPPORT
>  	select ARCH_CLOCKSOURCE_DATA
>  	select ARCH_HAS_ELF_RANDOMIZE
> -	select ARCH_HAS_PTE_SPECIAL
>  	select ARCH_HAS_TICK_BROADCAST if GENERIC_CLOCKEVENTS_BROADCAST
>  	select ARCH_HAS_UBSAN_SANITIZE_ALL
>  	select ARCH_SUPPORTS_UPROBES
> -- 
> 2.20.1
>