[PATCH V3 0/3] mm/hugetlb: Add some new generic fallbacks

[PATCH V3 0/3] mm/hugetlb: Add some new generic fallbacks

[Anshuman Khandual]

This series adds the following new generic fallbacks. Before that it drops
__HAVE_ARCH_HUGE_PTEP_GET from arm64 platform.

1. is_hugepage_only_range()
2. arch_clear_hugepage_flags()

This has been boot tested on arm64 and x86 platforms but built tested on
some more platforms including the changed ones here. This series applies
on v5.7-rc4. After this arm (32 bit) remains the sole platform defining
it's own huge_ptep_get() via __HAVE_ARCH_HUGE_PTEP_GET.

Changes in V3:

- Added READ_ONCE() in generic huge_ptep_get() per Will

Changes in V2: (https://patchwork.kernel.org/project/linux-mm/list/?series=282947)

- Adopted "#ifndef func" method (adding a single symbol to namespace) per Andrew
- Updated the commit messages in [PATCH 2/3] and [PATCH 3/3] as required

Changes in V1: (https://patchwork.kernel.org/project/linux-mm/list/?series=270677)

Cc: Russell King <linux@armlinux.org.uk>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Will Deacon <will@kernel.org>
Cc: Tony Luck <tony.luck@intel.com>
Cc: Fenghua Yu <fenghua.yu@intel.com>
Cc: Thomas Bogendoerfer <tsbogend@alpha.franken.de>
Cc: "James E.J. Bottomley" <James.Bottomley@HansenPartnership.com>
Cc: Helge Deller <deller@gmx.de>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Paul Walmsley <paul.walmsley@sifive.com>
Cc: Palmer Dabbelt <palmer@dabbelt.com>
Cc: Heiko Carstens <heiko.carstens@de.ibm.com>
Cc: Vasily Gorbik <gor@linux.ibm.com>
Cc: Christian Borntraeger <borntraeger@de.ibm.com>
Cc: Yoshinori Sato <ysato@users.sourceforge.jp>
Cc: Rich Felker <dalias@libc.org>
Cc: "David S. Miller" <davem@davemloft.net>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Borislav Petkov <bp@alien8.de>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Mike Kravetz <mike.kravetz@oracle.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: x86@kernel.org
Cc: linux-arm-kernel@lists.infradead.org
Cc: linux-ia64@vger.kernel.org
Cc: linux-mips@vger.kernel.org
Cc: linux-parisc@vger.kernel.org
Cc: linuxppc-dev@lists.ozlabs.org
Cc: linux-riscv@lists.infradead.org
Cc: linux-s390@vger.kernel.org
Cc: linux-sh@vger.kernel.org
Cc: sparclinux@vger.kernel.org
Cc: linux-mm@kvack.org
Cc: linux-arch@vger.kernel.org
Cc: linux-kernel@vger.kernel.org

Anshuman Khandual (3):
  arm64/mm: Drop __HAVE_ARCH_HUGE_PTEP_GET
  mm/hugetlb: Define a generic fallback for is_hugepage_only_range()
  mm/hugetlb: Define a generic fallback for arch_clear_hugepage_flags()

 arch/arm/include/asm/hugetlb.h     |  7 +------
 arch/arm64/include/asm/hugetlb.h   | 13 +------------
 arch/ia64/include/asm/hugetlb.h    |  5 +----
 arch/mips/include/asm/hugetlb.h    | 11 -----------
 arch/parisc/include/asm/hugetlb.h  | 10 ----------
 arch/powerpc/include/asm/hugetlb.h |  5 +----
 arch/riscv/include/asm/hugetlb.h   | 10 ----------
 arch/s390/include/asm/hugetlb.h    |  8 +-------
 arch/sh/include/asm/hugetlb.h      |  7 +------
 arch/sparc/include/asm/hugetlb.h   | 10 ----------
 arch/x86/include/asm/hugetlb.h     | 10 ----------
 include/asm-generic/hugetlb.h      |  2 +-
 include/linux/hugetlb.h            | 14 ++++++++++++++
 13 files changed, 21 insertions(+), 91 deletions(-)

-- 
2.20.1


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[PATCH V3 1/3] arm64/mm: Drop __HAVE_ARCH_HUGE_PTEP_GET

[Anshuman Khandual]

Platform specific huge_ptep_get() is required only when fetching the huge
PTE involves more than just dereferencing the page table pointer. This is
not the case on arm64 platform. Hence huge_ptep_pte() can be dropped along
with it's __HAVE_ARCH_HUGE_PTEP_GET subscription. Before that, it updates
the generic huge_ptep_get() with READ_ONCE() which will prevent known page
table issues with THP on arm64.

https://lore.kernel.org/r/1506527369-19535-1-git-send-email-will.deacon@arm.com/

Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Will Deacon <will@kernel.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: linux-arm-kernel@lists.infradead.org
Cc: linux-mm@kvack.org
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Anshuman Khandual <anshuman.khandual@arm.com>
---
 arch/arm64/include/asm/hugetlb.h | 6 ------
 include/asm-generic/hugetlb.h    | 2 +-
 2 files changed, 1 insertion(+), 7 deletions(-)

diff --git a/arch/arm64/include/asm/hugetlb.h b/arch/arm64/include/asm/hugetlb.h
index 2eb6c234d594..b88878ddc88b 100644
--- a/arch/arm64/include/asm/hugetlb.h
+++ b/arch/arm64/include/asm/hugetlb.h
@@ -17,12 +17,6 @@
 extern bool arch_hugetlb_migration_supported(struct hstate *h);
 #endif
 
-#define __HAVE_ARCH_HUGE_PTEP_GET
-static inline pte_t huge_ptep_get(pte_t *ptep)
-{
-	return READ_ONCE(*ptep);
-}
-
 static inline int is_hugepage_only_range(struct mm_struct *mm,
 					 unsigned long addr, unsigned long len)
 {
diff --git a/include/asm-generic/hugetlb.h b/include/asm-generic/hugetlb.h
index 822f433ac95c..40f85decc2ee 100644
--- a/include/asm-generic/hugetlb.h
+++ b/include/asm-generic/hugetlb.h
@@ -122,7 +122,7 @@ static inline int huge_ptep_set_access_flags(struct vm_area_struct *vma,
 #ifndef __HAVE_ARCH_HUGE_PTEP_GET
 static inline pte_t huge_ptep_get(pte_t *ptep)
 {
-	return *ptep;
+	return READ_ONCE(*ptep);
 }
 #endif
 
-- 
2.20.1


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Re: [PATCH V3 1/3] arm64/mm: Drop __HAVE_ARCH_HUGE_PTEP_GET

[Mike Kravetz]

On 5/7/20 8:07 PM, Anshuman Khandual wrote:
> Platform specific huge_ptep_get() is required only when fetching the huge
> PTE involves more than just dereferencing the page table pointer. This is
> not the case on arm64 platform. Hence huge_ptep_pte() can be dropped along
> with it's __HAVE_ARCH_HUGE_PTEP_GET subscription. Before that, it updates
> the generic huge_ptep_get() with READ_ONCE() which will prevent known page
> table issues with THP on arm64.
> 
> https://lore.kernel.org/r/1506527369-19535-1-git-send-email-will.deacon@arm.com/
> 
> Cc: Catalin Marinas <catalin.marinas@arm.com>
> Cc: Will Deacon <will@kernel.org>
> Cc: Andrew Morton <akpm@linux-foundation.org>
> Cc: linux-arm-kernel@lists.infradead.org
> Cc: linux-mm@kvack.org
> Cc: linux-kernel@vger.kernel.org
> Signed-off-by: Anshuman Khandual <anshuman.khandual@arm.com>
> ---
>  arch/arm64/include/asm/hugetlb.h | 6 ------
>  include/asm-generic/hugetlb.h    | 2 +-
>  2 files changed, 1 insertion(+), 7 deletions(-)
> 
> diff --git a/arch/arm64/include/asm/hugetlb.h b/arch/arm64/include/asm/hugetlb.h
> index 2eb6c234d594..b88878ddc88b 100644
> --- a/arch/arm64/include/asm/hugetlb.h
> +++ b/arch/arm64/include/asm/hugetlb.h
> @@ -17,12 +17,6 @@
>  extern bool arch_hugetlb_migration_supported(struct hstate *h);
>  #endif
>  
> -#define __HAVE_ARCH_HUGE_PTEP_GET
> -static inline pte_t huge_ptep_get(pte_t *ptep)
> -{
> -	return READ_ONCE(*ptep);
> -}
> -
>  static inline int is_hugepage_only_range(struct mm_struct *mm,
>  					 unsigned long addr, unsigned long len)
>  {
> diff --git a/include/asm-generic/hugetlb.h b/include/asm-generic/hugetlb.h
> index 822f433ac95c..40f85decc2ee 100644
> --- a/include/asm-generic/hugetlb.h
> +++ b/include/asm-generic/hugetlb.h
> @@ -122,7 +122,7 @@ static inline int huge_ptep_set_access_flags(struct vm_area_struct *vma,
>  #ifndef __HAVE_ARCH_HUGE_PTEP_GET
>  static inline pte_t huge_ptep_get(pte_t *ptep)
>  {
> -	return *ptep;
> +	return READ_ONCE(*ptep);
>  }
>  #endif

I know you made this change in response to Will's comment.  And, since
changes were made to consistently use READ_ONCE in arm64 code, it makes
sense for that architecture.

However, with this change to generic code, you introduce READ_ONCE to
other architectures where it was not used before.  Could this possibly
introduce inconsistencies in their use of READ_ONCE?  To be honest, I
am not very good at identifying any possible issues this could cause.
However, it does seem possible.

Will was nervous about dropping this from arm64.  I'm just a little nervous
about adding it to other architectures.
-- 
Mike Kravetz

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Re: [PATCH V3 1/3] arm64/mm: Drop __HAVE_ARCH_HUGE_PTEP_GET

[Anshuman Khandual]

On 05/09/2020 03:39 AM, Mike Kravetz wrote:
> On 5/7/20 8:07 PM, Anshuman Khandual wrote:
>> Platform specific huge_ptep_get() is required only when fetching the huge
>> PTE involves more than just dereferencing the page table pointer. This is
>> not the case on arm64 platform. Hence huge_ptep_pte() can be dropped along
>> with it's __HAVE_ARCH_HUGE_PTEP_GET subscription. Before that, it updates
>> the generic huge_ptep_get() with READ_ONCE() which will prevent known page
>> table issues with THP on arm64.
>>
>> https://lore.kernel.org/r/1506527369-19535-1-git-send-email-will.deacon@arm.com/
>>
>> Cc: Catalin Marinas <catalin.marinas@arm.com>
>> Cc: Will Deacon <will@kernel.org>
>> Cc: Andrew Morton <akpm@linux-foundation.org>
>> Cc: linux-arm-kernel@lists.infradead.org
>> Cc: linux-mm@kvack.org
>> Cc: linux-kernel@vger.kernel.org
>> Signed-off-by: Anshuman Khandual <anshuman.khandual@arm.com>
>> ---
>>  arch/arm64/include/asm/hugetlb.h | 6 ------
>>  include/asm-generic/hugetlb.h    | 2 +-
>>  2 files changed, 1 insertion(+), 7 deletions(-)
>>
>> diff --git a/arch/arm64/include/asm/hugetlb.h b/arch/arm64/include/asm/hugetlb.h
>> index 2eb6c234d594..b88878ddc88b 100644
>> --- a/arch/arm64/include/asm/hugetlb.h
>> +++ b/arch/arm64/include/asm/hugetlb.h
>> @@ -17,12 +17,6 @@
>>  extern bool arch_hugetlb_migration_supported(struct hstate *h);
>>  #endif
>>  
>> -#define __HAVE_ARCH_HUGE_PTEP_GET
>> -static inline pte_t huge_ptep_get(pte_t *ptep)
>> -{
>> -	return READ_ONCE(*ptep);
>> -}
>> -
>>  static inline int is_hugepage_only_range(struct mm_struct *mm,
>>  					 unsigned long addr, unsigned long len)
>>  {
>> diff --git a/include/asm-generic/hugetlb.h b/include/asm-generic/hugetlb.h
>> index 822f433ac95c..40f85decc2ee 100644
>> --- a/include/asm-generic/hugetlb.h
>> +++ b/include/asm-generic/hugetlb.h
>> @@ -122,7 +122,7 @@ static inline int huge_ptep_set_access_flags(struct vm_area_struct *vma,
>>  #ifndef __HAVE_ARCH_HUGE_PTEP_GET
>>  static inline pte_t huge_ptep_get(pte_t *ptep)
>>  {
>> -	return *ptep;
>> +	return READ_ONCE(*ptep);
>>  }
>>  #endif
> 
> I know you made this change in response to Will's comment.  And, since
> changes were made to consistently use READ_ONCE in arm64 code, it makes
> sense for that architecture.
> 
> However, with this change to generic code, you introduce READ_ONCE to
> other architectures where it was not used before.  Could this possibly
> introduce inconsistencies in their use of READ_ONCE?  To be honest, I
> am not very good at identifying any possible issues this could cause.
> However, it does seem possible.

Could you please give some more details. Is there any particular problem
which might be caused by this new READ_ONCE() here, that you you are
concerned about. READ_ONCE() is already getting used in multiple places
in core MM which can not be configured out (like mm/gup.c). It is getting
used in core HugeTLB (mm/hugetlb.c) as well. AFAICS, there is no standard
for using READ_ONCE() while walking page tables entries. We have examples
in core MM for both ways.

> 
> Will was nervous about dropping this from arm64.  I'm just a little nervous
> about adding it to other architectures.
> 
AFAICS, __HAVE_ARCH_HUGE_PTEP_GET should be used on a platform only when
a HugeTLB entry could not constructed by dereferencing a page table entry
as in the case with ARM (32 bit). Using READ_ONCE() while dereferencing is
really not a special case that will need __HAVE_ARCH_HUGE_PTEP_GET. Moving
READ_ONCE() into generic definition solves the problem while also taking
care of a known problem on arm64. IMHO, it seems like the right thing to
do unless there is another problem that pops up some where else because of
READ_ONCE().

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Re: [PATCH V3 1/3] arm64/mm: Drop __HAVE_ARCH_HUGE_PTEP_GET

[Mike Kravetz]

On 5/10/20 9:02 PM, Anshuman Khandual wrote:
> On 05/09/2020 03:39 AM, Mike Kravetz wrote:
>> On 5/7/20 8:07 PM, Anshuman Khandual wrote:
>> I know you made this change in response to Will's comment.  And, since
>> changes were made to consistently use READ_ONCE in arm64 code, it makes
>> sense for that architecture.
>>
>> However, with this change to generic code, you introduce READ_ONCE to
>> other architectures where it was not used before.  Could this possibly
>> introduce inconsistencies in their use of READ_ONCE?  To be honest, I
>> am not very good at identifying any possible issues this could cause.
>> However, it does seem possible.
> 
> Could you please give some more details. Is there any particular problem
> which might be caused by this new READ_ONCE() here, that you you are
> concerned about. READ_ONCE() is already getting used in multiple places
> in core MM which can not be configured out (like mm/gup.c). It is getting
> used in core HugeTLB (mm/hugetlb.c) as well. AFAICS, there is no standard
> for using READ_ONCE() while walking page tables entries. We have examples
> in core MM for both ways.
> 
>>
>> Will was nervous about dropping this from arm64.  I'm just a little nervous
>> about adding it to other architectures.
>>
> AFAICS, __HAVE_ARCH_HUGE_PTEP_GET should be used on a platform only when
> a HugeTLB entry could not constructed by dereferencing a page table entry
> as in the case with ARM (32 bit). Using READ_ONCE() while dereferencing is
> really not a special case that will need __HAVE_ARCH_HUGE_PTEP_GET. Moving
> READ_ONCE() into generic definition solves the problem while also taking
> care of a known problem on arm64. IMHO, it seems like the right thing to
> do unless there is another problem that pops up some where else because of
> READ_ONCE().

I have no specific concerns or objection.  After thinking about it some more,
I do not see how adding the READ_ONCE could cause any issues.

Acked-by: Mike Kravetz <mike.kravetz@oracle.com>

-- 
Mike Kravetz

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[PATCH V3 2/3] mm/hugetlb: Define a generic fallback for is_hugepage_only_range()

[Anshuman Khandual]

There are multiple similar definitions for is_hugepage_only_range() on
various platforms. Lets just add it's generic fallback definition for
platforms that do not override. This help reduce code duplication.

Cc: Russell King <linux@armlinux.org.uk>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Will Deacon <will@kernel.org>
Cc: Tony Luck <tony.luck@intel.com>
Cc: Fenghua Yu <fenghua.yu@intel.com>
Cc: Thomas Bogendoerfer <tsbogend@alpha.franken.de>
Cc: "James E.J. Bottomley" <James.Bottomley@HansenPartnership.com>
Cc: Helge Deller <deller@gmx.de>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Paul Walmsley <paul.walmsley@sifive.com>
Cc: Palmer Dabbelt <palmer@dabbelt.com>
Cc: Heiko Carstens <heiko.carstens@de.ibm.com>
Cc: Vasily Gorbik <gor@linux.ibm.com>
Cc: Christian Borntraeger <borntraeger@de.ibm.com>
Cc: Yoshinori Sato <ysato@users.sourceforge.jp>
Cc: Rich Felker <dalias@libc.org>
Cc: "David S. Miller" <davem@davemloft.net>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Borislav Petkov <bp@alien8.de>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Mike Kravetz <mike.kravetz@oracle.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: x86@kernel.org
Cc: linux-arm-kernel@lists.infradead.org
Cc: linux-ia64@vger.kernel.org
Cc: linux-mips@vger.kernel.org
Cc: linux-parisc@vger.kernel.org
Cc: linuxppc-dev@lists.ozlabs.org
Cc: linux-riscv@lists.infradead.org
Cc: linux-s390@vger.kernel.org
Cc: linux-sh@vger.kernel.org
Cc: sparclinux@vger.kernel.org
Cc: linux-mm@kvack.org
Cc: linux-arch@vger.kernel.org
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Anshuman Khandual <anshuman.khandual@arm.com>
---
 arch/arm/include/asm/hugetlb.h     | 6 ------
 arch/arm64/include/asm/hugetlb.h   | 6 ------
 arch/ia64/include/asm/hugetlb.h    | 1 +
 arch/mips/include/asm/hugetlb.h    | 7 -------
 arch/parisc/include/asm/hugetlb.h  | 6 ------
 arch/powerpc/include/asm/hugetlb.h | 1 +
 arch/riscv/include/asm/hugetlb.h   | 6 ------
 arch/s390/include/asm/hugetlb.h    | 7 -------
 arch/sh/include/asm/hugetlb.h      | 6 ------
 arch/sparc/include/asm/hugetlb.h   | 6 ------
 arch/x86/include/asm/hugetlb.h     | 6 ------
 include/linux/hugetlb.h            | 9 +++++++++
 12 files changed, 11 insertions(+), 56 deletions(-)

diff --git a/arch/arm/include/asm/hugetlb.h b/arch/arm/include/asm/hugetlb.h
index 318dcf5921ab..9ecd516d1ff7 100644
--- a/arch/arm/include/asm/hugetlb.h
+++ b/arch/arm/include/asm/hugetlb.h
@@ -14,12 +14,6 @@
 #include <asm/hugetlb-3level.h>
 #include <asm-generic/hugetlb.h>
 
-static inline int is_hugepage_only_range(struct mm_struct *mm,
-					 unsigned long addr, unsigned long len)
-{
-	return 0;
-}
-
 static inline void arch_clear_hugepage_flags(struct page *page)
 {
 	clear_bit(PG_dcache_clean, &page->flags);
diff --git a/arch/arm64/include/asm/hugetlb.h b/arch/arm64/include/asm/hugetlb.h
index b88878ddc88b..8f58e052697a 100644
--- a/arch/arm64/include/asm/hugetlb.h
+++ b/arch/arm64/include/asm/hugetlb.h
@@ -17,12 +17,6 @@
 extern bool arch_hugetlb_migration_supported(struct hstate *h);
 #endif
 
-static inline int is_hugepage_only_range(struct mm_struct *mm,
-					 unsigned long addr, unsigned long len)
-{
-	return 0;
-}
-
 static inline void arch_clear_hugepage_flags(struct page *page)
 {
 	clear_bit(PG_dcache_clean, &page->flags);
diff --git a/arch/ia64/include/asm/hugetlb.h b/arch/ia64/include/asm/hugetlb.h
index 36cc0396b214..6ef50b9a4bdf 100644
--- a/arch/ia64/include/asm/hugetlb.h
+++ b/arch/ia64/include/asm/hugetlb.h
@@ -20,6 +20,7 @@ static inline int is_hugepage_only_range(struct mm_struct *mm,
 	return (REGION_NUMBER(addr) == RGN_HPAGE ||
 		REGION_NUMBER((addr)+(len)-1) == RGN_HPAGE);
 }
+#define is_hugepage_only_range is_hugepage_only_range
 
 #define __HAVE_ARCH_HUGE_PTEP_CLEAR_FLUSH
 static inline void huge_ptep_clear_flush(struct vm_area_struct *vma,
diff --git a/arch/mips/include/asm/hugetlb.h b/arch/mips/include/asm/hugetlb.h
index 425bb6fc3bda..8b201e281f67 100644
--- a/arch/mips/include/asm/hugetlb.h
+++ b/arch/mips/include/asm/hugetlb.h
@@ -11,13 +11,6 @@
 
 #include <asm/page.h>
 
-static inline int is_hugepage_only_range(struct mm_struct *mm,
-					 unsigned long addr,
-					 unsigned long len)
-{
-	return 0;
-}
-
 #define __HAVE_ARCH_PREPARE_HUGEPAGE_RANGE
 static inline int prepare_hugepage_range(struct file *file,
 					 unsigned long addr,
diff --git a/arch/parisc/include/asm/hugetlb.h b/arch/parisc/include/asm/hugetlb.h
index 7cb595dcb7d7..411d9d867baa 100644
--- a/arch/parisc/include/asm/hugetlb.h
+++ b/arch/parisc/include/asm/hugetlb.h
@@ -12,12 +12,6 @@ void set_huge_pte_at(struct mm_struct *mm, unsigned long addr,
 pte_t huge_ptep_get_and_clear(struct mm_struct *mm, unsigned long addr,
 			      pte_t *ptep);
 
-static inline int is_hugepage_only_range(struct mm_struct *mm,
-					 unsigned long addr,
-					 unsigned long len) {
-	return 0;
-}
-
 /*
  * If the arch doesn't supply something else, assume that hugepage
  * size aligned regions are ok without further preparation.
diff --git a/arch/powerpc/include/asm/hugetlb.h b/arch/powerpc/include/asm/hugetlb.h
index bd6504c28c2f..b167c869d72d 100644
--- a/arch/powerpc/include/asm/hugetlb.h
+++ b/arch/powerpc/include/asm/hugetlb.h
@@ -30,6 +30,7 @@ static inline int is_hugepage_only_range(struct mm_struct *mm,
 		return slice_is_hugepage_only_range(mm, addr, len);
 	return 0;
 }
+#define is_hugepage_only_range is_hugepage_only_range
 
 #define __HAVE_ARCH_HUGETLB_FREE_PGD_RANGE
 void hugetlb_free_pgd_range(struct mmu_gather *tlb, unsigned long addr,
diff --git a/arch/riscv/include/asm/hugetlb.h b/arch/riscv/include/asm/hugetlb.h
index 728a5db66597..866f6ae6467c 100644
--- a/arch/riscv/include/asm/hugetlb.h
+++ b/arch/riscv/include/asm/hugetlb.h
@@ -5,12 +5,6 @@
 #include <asm-generic/hugetlb.h>
 #include <asm/page.h>
 
-static inline int is_hugepage_only_range(struct mm_struct *mm,
-					 unsigned long addr,
-					 unsigned long len) {
-	return 0;
-}
-
 static inline void arch_clear_hugepage_flags(struct page *page)
 {
 }
diff --git a/arch/s390/include/asm/hugetlb.h b/arch/s390/include/asm/hugetlb.h
index de8f0bf5f238..7d27ea96ec2f 100644
--- a/arch/s390/include/asm/hugetlb.h
+++ b/arch/s390/include/asm/hugetlb.h
@@ -21,13 +21,6 @@ pte_t huge_ptep_get(pte_t *ptep);
 pte_t huge_ptep_get_and_clear(struct mm_struct *mm,
 			      unsigned long addr, pte_t *ptep);
 
-static inline bool is_hugepage_only_range(struct mm_struct *mm,
-					  unsigned long addr,
-					  unsigned long len)
-{
-	return false;
-}
-
 /*
  * If the arch doesn't supply something else, assume that hugepage
  * size aligned regions are ok without further preparation.
diff --git a/arch/sh/include/asm/hugetlb.h b/arch/sh/include/asm/hugetlb.h
index 6f025fe18146..536ad2cb8aa4 100644
--- a/arch/sh/include/asm/hugetlb.h
+++ b/arch/sh/include/asm/hugetlb.h
@@ -5,12 +5,6 @@
 #include <asm/cacheflush.h>
 #include <asm/page.h>
 
-static inline int is_hugepage_only_range(struct mm_struct *mm,
-					 unsigned long addr,
-					 unsigned long len) {
-	return 0;
-}
-
 /*
  * If the arch doesn't supply something else, assume that hugepage
  * size aligned regions are ok without further preparation.
diff --git a/arch/sparc/include/asm/hugetlb.h b/arch/sparc/include/asm/hugetlb.h
index 3963f80d1cb3..a056fe1119f5 100644
--- a/arch/sparc/include/asm/hugetlb.h
+++ b/arch/sparc/include/asm/hugetlb.h
@@ -20,12 +20,6 @@ void set_huge_pte_at(struct mm_struct *mm, unsigned long addr,
 pte_t huge_ptep_get_and_clear(struct mm_struct *mm, unsigned long addr,
 			      pte_t *ptep);
 
-static inline int is_hugepage_only_range(struct mm_struct *mm,
-					 unsigned long addr,
-					 unsigned long len) {
-	return 0;
-}
-
 #define __HAVE_ARCH_HUGE_PTEP_CLEAR_FLUSH
 static inline void huge_ptep_clear_flush(struct vm_area_struct *vma,
 					 unsigned long addr, pte_t *ptep)
diff --git a/arch/x86/include/asm/hugetlb.h b/arch/x86/include/asm/hugetlb.h
index f65cfb48cfdd..cc98f79074d0 100644
--- a/arch/x86/include/asm/hugetlb.h
+++ b/arch/x86/include/asm/hugetlb.h
@@ -7,12 +7,6 @@
 
 #define hugepages_supported() boot_cpu_has(X86_FEATURE_PSE)
 
-static inline int is_hugepage_only_range(struct mm_struct *mm,
-					 unsigned long addr,
-					 unsigned long len) {
-	return 0;
-}
-
 static inline void arch_clear_hugepage_flags(struct page *page)
 {
 }
diff --git a/include/linux/hugetlb.h b/include/linux/hugetlb.h
index 43a1cef8f0f1..c01c0c6f7fd4 100644
--- a/include/linux/hugetlb.h
+++ b/include/linux/hugetlb.h
@@ -591,6 +591,15 @@ static inline unsigned int blocks_per_huge_page(struct hstate *h)
 
 #include <asm/hugetlb.h>
 
+#ifndef is_hugepage_only_range
+static inline int is_hugepage_only_range(struct mm_struct *mm,
+					unsigned long addr, unsigned long len)
+{
+	return 0;
+}
+#define is_hugepage_only_range is_hugepage_only_range
+#endif
+
 #ifndef arch_make_huge_pte
 static inline pte_t arch_make_huge_pte(pte_t entry, struct vm_area_struct *vma,
 				       struct page *page, int writable)
-- 
2.20.1


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Re: [PATCH V3 2/3] mm/hugetlb: Define a generic fallback for is_hugepage_only_range()

[Mike Kravetz]

On 5/7/20 8:07 PM, Anshuman Khandual wrote:
> There are multiple similar definitions for is_hugepage_only_range() on
> various platforms. Lets just add it's generic fallback definition for
> platforms that do not override. This help reduce code duplication.
> 
> Cc: Russell King <linux@armlinux.org.uk>
> Cc: Catalin Marinas <catalin.marinas@arm.com>
> Cc: Will Deacon <will@kernel.org>
> Cc: Tony Luck <tony.luck@intel.com>
> Cc: Fenghua Yu <fenghua.yu@intel.com>
> Cc: Thomas Bogendoerfer <tsbogend@alpha.franken.de>
> Cc: "James E.J. Bottomley" <James.Bottomley@HansenPartnership.com>
> Cc: Helge Deller <deller@gmx.de>
> Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
> Cc: Paul Mackerras <paulus@samba.org>
> Cc: Michael Ellerman <mpe@ellerman.id.au>
> Cc: Paul Walmsley <paul.walmsley@sifive.com>
> Cc: Palmer Dabbelt <palmer@dabbelt.com>
> Cc: Heiko Carstens <heiko.carstens@de.ibm.com>
> Cc: Vasily Gorbik <gor@linux.ibm.com>
> Cc: Christian Borntraeger <borntraeger@de.ibm.com>
> Cc: Yoshinori Sato <ysato@users.sourceforge.jp>
> Cc: Rich Felker <dalias@libc.org>
> Cc: "David S. Miller" <davem@davemloft.net>
> Cc: Thomas Gleixner <tglx@linutronix.de>
> Cc: Ingo Molnar <mingo@redhat.com>
> Cc: Borislav Petkov <bp@alien8.de>
> Cc: "H. Peter Anvin" <hpa@zytor.com>
> Cc: Mike Kravetz <mike.kravetz@oracle.com>
> Cc: Andrew Morton <akpm@linux-foundation.org>
> Cc: x86@kernel.org
> Cc: linux-arm-kernel@lists.infradead.org
> Cc: linux-ia64@vger.kernel.org
> Cc: linux-mips@vger.kernel.org
> Cc: linux-parisc@vger.kernel.org
> Cc: linuxppc-dev@lists.ozlabs.org
> Cc: linux-riscv@lists.infradead.org
> Cc: linux-s390@vger.kernel.org
> Cc: linux-sh@vger.kernel.org
> Cc: sparclinux@vger.kernel.org
> Cc: linux-mm@kvack.org
> Cc: linux-arch@vger.kernel.org
> Cc: linux-kernel@vger.kernel.org
> Signed-off-by: Anshuman Khandual <anshuman.khandual@arm.com>
> ---
>  arch/arm/include/asm/hugetlb.h     | 6 ------
>  arch/arm64/include/asm/hugetlb.h   | 6 ------
>  arch/ia64/include/asm/hugetlb.h    | 1 +
>  arch/mips/include/asm/hugetlb.h    | 7 -------
>  arch/parisc/include/asm/hugetlb.h  | 6 ------
>  arch/powerpc/include/asm/hugetlb.h | 1 +
>  arch/riscv/include/asm/hugetlb.h   | 6 ------
>  arch/s390/include/asm/hugetlb.h    | 7 -------
>  arch/sh/include/asm/hugetlb.h      | 6 ------
>  arch/sparc/include/asm/hugetlb.h   | 6 ------
>  arch/x86/include/asm/hugetlb.h     | 6 ------
>  include/linux/hugetlb.h            | 9 +++++++++
>  12 files changed, 11 insertions(+), 56 deletions(-)
> 
<snip>
> diff --git a/include/linux/hugetlb.h b/include/linux/hugetlb.h
> index 43a1cef8f0f1..c01c0c6f7fd4 100644
> --- a/include/linux/hugetlb.h
> +++ b/include/linux/hugetlb.h
> @@ -591,6 +591,15 @@ static inline unsigned int blocks_per_huge_page(struct hstate *h)
>  
>  #include <asm/hugetlb.h>
>  
> +#ifndef is_hugepage_only_range
> +static inline int is_hugepage_only_range(struct mm_struct *mm,
> +					unsigned long addr, unsigned long len)
> +{
> +	return 0;
> +}
> +#define is_hugepage_only_range is_hugepage_only_range
> +#endif
> +
>  #ifndef arch_make_huge_pte
>  static inline pte_t arch_make_huge_pte(pte_t entry, struct vm_area_struct *vma,
>  				       struct page *page, int writable)
> 

Did you try building without CONFIG_HUGETLB_PAGE defined?  I'm guessing
that you need a stub for is_hugepage_only_range().  Or, perhaps add this
to asm-generic/hugetlb.h?

-- 
Mike Kravetz

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Re: [PATCH V3 2/3] mm/hugetlb: Define a generic fallback for is_hugepage_only_range()

[Anshuman Khandual]

On 05/09/2020 03:52 AM, Mike Kravetz wrote:
> On 5/7/20 8:07 PM, Anshuman Khandual wrote:
>> There are multiple similar definitions for is_hugepage_only_range() on
>> various platforms. Lets just add it's generic fallback definition for
>> platforms that do not override. This help reduce code duplication.
>>
>> Cc: Russell King <linux@armlinux.org.uk>
>> Cc: Catalin Marinas <catalin.marinas@arm.com>
>> Cc: Will Deacon <will@kernel.org>
>> Cc: Tony Luck <tony.luck@intel.com>
>> Cc: Fenghua Yu <fenghua.yu@intel.com>
>> Cc: Thomas Bogendoerfer <tsbogend@alpha.franken.de>
>> Cc: "James E.J. Bottomley" <James.Bottomley@HansenPartnership.com>
>> Cc: Helge Deller <deller@gmx.de>
>> Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
>> Cc: Paul Mackerras <paulus@samba.org>
>> Cc: Michael Ellerman <mpe@ellerman.id.au>
>> Cc: Paul Walmsley <paul.walmsley@sifive.com>
>> Cc: Palmer Dabbelt <palmer@dabbelt.com>
>> Cc: Heiko Carstens <heiko.carstens@de.ibm.com>
>> Cc: Vasily Gorbik <gor@linux.ibm.com>
>> Cc: Christian Borntraeger <borntraeger@de.ibm.com>
>> Cc: Yoshinori Sato <ysato@users.sourceforge.jp>
>> Cc: Rich Felker <dalias@libc.org>
>> Cc: "David S. Miller" <davem@davemloft.net>
>> Cc: Thomas Gleixner <tglx@linutronix.de>
>> Cc: Ingo Molnar <mingo@redhat.com>
>> Cc: Borislav Petkov <bp@alien8.de>
>> Cc: "H. Peter Anvin" <hpa@zytor.com>
>> Cc: Mike Kravetz <mike.kravetz@oracle.com>
>> Cc: Andrew Morton <akpm@linux-foundation.org>
>> Cc: x86@kernel.org
>> Cc: linux-arm-kernel@lists.infradead.org
>> Cc: linux-ia64@vger.kernel.org
>> Cc: linux-mips@vger.kernel.org
>> Cc: linux-parisc@vger.kernel.org
>> Cc: linuxppc-dev@lists.ozlabs.org
>> Cc: linux-riscv@lists.infradead.org
>> Cc: linux-s390@vger.kernel.org
>> Cc: linux-sh@vger.kernel.org
>> Cc: sparclinux@vger.kernel.org
>> Cc: linux-mm@kvack.org
>> Cc: linux-arch@vger.kernel.org
>> Cc: linux-kernel@vger.kernel.org
>> Signed-off-by: Anshuman Khandual <anshuman.khandual@arm.com>
>> ---
>>  arch/arm/include/asm/hugetlb.h     | 6 ------
>>  arch/arm64/include/asm/hugetlb.h   | 6 ------
>>  arch/ia64/include/asm/hugetlb.h    | 1 +
>>  arch/mips/include/asm/hugetlb.h    | 7 -------
>>  arch/parisc/include/asm/hugetlb.h  | 6 ------
>>  arch/powerpc/include/asm/hugetlb.h | 1 +
>>  arch/riscv/include/asm/hugetlb.h   | 6 ------
>>  arch/s390/include/asm/hugetlb.h    | 7 -------
>>  arch/sh/include/asm/hugetlb.h      | 6 ------
>>  arch/sparc/include/asm/hugetlb.h   | 6 ------
>>  arch/x86/include/asm/hugetlb.h     | 6 ------
>>  include/linux/hugetlb.h            | 9 +++++++++
>>  12 files changed, 11 insertions(+), 56 deletions(-)
>>
> <snip>
>> diff --git a/include/linux/hugetlb.h b/include/linux/hugetlb.h
>> index 43a1cef8f0f1..c01c0c6f7fd4 100644
>> --- a/include/linux/hugetlb.h
>> +++ b/include/linux/hugetlb.h
>> @@ -591,6 +591,15 @@ static inline unsigned int blocks_per_huge_page(struct hstate *h)
>>  
>>  #include <asm/hugetlb.h>
>>  
>> +#ifndef is_hugepage_only_range
>> +static inline int is_hugepage_only_range(struct mm_struct *mm,
>> +					unsigned long addr, unsigned long len)
>> +{
>> +	return 0;
>> +}
>> +#define is_hugepage_only_range is_hugepage_only_range
>> +#endif
>> +
>>  #ifndef arch_make_huge_pte
>>  static inline pte_t arch_make_huge_pte(pte_t entry, struct vm_area_struct *vma,
>>  				       struct page *page, int writable)
>>
> 
> Did you try building without CONFIG_HUGETLB_PAGE defined?  I'm guessing

Yes I did for multiple platforms (s390, arm64, ia64, x86, powerpc etc).

> that you need a stub for is_hugepage_only_range().  Or, perhaps add this
> to asm-generic/hugetlb.h?
> 
There is already a stub (include/linux/hugetlb.h) when !CONFIG_HUGETLB_PAGE.

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Re: [PATCH V3 2/3] mm/hugetlb: Define a generic fallback for is_hugepage_only_range()

[Mike Kravetz]

On 5/10/20 8:14 PM, Anshuman Khandual wrote:
> On 05/09/2020 03:52 AM, Mike Kravetz wrote:
>> On 5/7/20 8:07 PM, Anshuman Khandual wrote:
>>
>> Did you try building without CONFIG_HUGETLB_PAGE defined?  I'm guessing
> 
> Yes I did for multiple platforms (s390, arm64, ia64, x86, powerpc etc).
> 
>> that you need a stub for is_hugepage_only_range().  Or, perhaps add this
>> to asm-generic/hugetlb.h?
>>
> There is already a stub (include/linux/hugetlb.h) when !CONFIG_HUGETLB_PAGE.
> 

Thanks!  I missed that stub in the existing code.  I like the removal of
redundant code.

Acked-by: Mike Kravetz <mike.kravetz@oracle.com>

-- 
Mike Kravetz

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[PATCH V3 3/3] mm/hugetlb: Define a generic fallback for arch_clear_hugepage_flags()

[Anshuman Khandual]

There are multiple similar definitions for arch_clear_hugepage_flags() on
various platforms. Lets just add it's generic fallback definition for
platforms that do not override. This help reduce code duplication.

Cc: Russell King <linux@armlinux.org.uk>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Will Deacon <will@kernel.org>
Cc: Tony Luck <tony.luck@intel.com>
Cc: Fenghua Yu <fenghua.yu@intel.com>
Cc: Thomas Bogendoerfer <tsbogend@alpha.franken.de>
Cc: "James E.J. Bottomley" <James.Bottomley@HansenPartnership.com>
Cc: Helge Deller <deller@gmx.de>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Paul Walmsley <paul.walmsley@sifive.com>
Cc: Palmer Dabbelt <palmer@dabbelt.com>
Cc: Heiko Carstens <heiko.carstens@de.ibm.com>
Cc: Vasily Gorbik <gor@linux.ibm.com>
Cc: Christian Borntraeger <borntraeger@de.ibm.com>
Cc: Yoshinori Sato <ysato@users.sourceforge.jp>
Cc: Rich Felker <dalias@libc.org>
Cc: "David S. Miller" <davem@davemloft.net>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Borislav Petkov <bp@alien8.de>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Mike Kravetz <mike.kravetz@oracle.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: x86@kernel.org
Cc: linux-arm-kernel@lists.infradead.org
Cc: linux-ia64@vger.kernel.org
Cc: linux-mips@vger.kernel.org
Cc: linux-parisc@vger.kernel.org
Cc: linuxppc-dev@lists.ozlabs.org
Cc: linux-riscv@lists.infradead.org
Cc: linux-s390@vger.kernel.org
Cc: linux-sh@vger.kernel.org
Cc: sparclinux@vger.kernel.org
Cc: linux-mm@kvack.org
Cc: linux-arch@vger.kernel.org
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Anshuman Khandual <anshuman.khandual@arm.com>
---
 arch/arm/include/asm/hugetlb.h     | 1 +
 arch/arm64/include/asm/hugetlb.h   | 1 +
 arch/ia64/include/asm/hugetlb.h    | 4 ----
 arch/mips/include/asm/hugetlb.h    | 4 ----
 arch/parisc/include/asm/hugetlb.h  | 4 ----
 arch/powerpc/include/asm/hugetlb.h | 4 ----
 arch/riscv/include/asm/hugetlb.h   | 4 ----
 arch/s390/include/asm/hugetlb.h    | 1 +
 arch/sh/include/asm/hugetlb.h      | 1 +
 arch/sparc/include/asm/hugetlb.h   | 4 ----
 arch/x86/include/asm/hugetlb.h     | 4 ----
 include/linux/hugetlb.h            | 5 +++++
 12 files changed, 9 insertions(+), 28 deletions(-)

diff --git a/arch/arm/include/asm/hugetlb.h b/arch/arm/include/asm/hugetlb.h
index 9ecd516d1ff7..d02d6ca88e92 100644
--- a/arch/arm/include/asm/hugetlb.h
+++ b/arch/arm/include/asm/hugetlb.h
@@ -18,5 +18,6 @@ static inline void arch_clear_hugepage_flags(struct page *page)
 {
 	clear_bit(PG_dcache_clean, &page->flags);
 }
+#define arch_clear_hugepage_flags arch_clear_hugepage_flags
 
 #endif /* _ASM_ARM_HUGETLB_H */
diff --git a/arch/arm64/include/asm/hugetlb.h b/arch/arm64/include/asm/hugetlb.h
index 8f58e052697a..94ba0c5bced2 100644
--- a/arch/arm64/include/asm/hugetlb.h
+++ b/arch/arm64/include/asm/hugetlb.h
@@ -21,6 +21,7 @@ static inline void arch_clear_hugepage_flags(struct page *page)
 {
 	clear_bit(PG_dcache_clean, &page->flags);
 }
+#define arch_clear_hugepage_flags arch_clear_hugepage_flags
 
 extern pte_t arch_make_huge_pte(pte_t entry, struct vm_area_struct *vma,
 				struct page *page, int writable);
diff --git a/arch/ia64/include/asm/hugetlb.h b/arch/ia64/include/asm/hugetlb.h
index 6ef50b9a4bdf..7e46ebde8c0c 100644
--- a/arch/ia64/include/asm/hugetlb.h
+++ b/arch/ia64/include/asm/hugetlb.h
@@ -28,10 +28,6 @@ static inline void huge_ptep_clear_flush(struct vm_area_struct *vma,
 {
 }
 
-static inline void arch_clear_hugepage_flags(struct page *page)
-{
-}
-
 #include <asm-generic/hugetlb.h>
 
 #endif /* _ASM_IA64_HUGETLB_H */
diff --git a/arch/mips/include/asm/hugetlb.h b/arch/mips/include/asm/hugetlb.h
index 8b201e281f67..10e3be870df7 100644
--- a/arch/mips/include/asm/hugetlb.h
+++ b/arch/mips/include/asm/hugetlb.h
@@ -75,10 +75,6 @@ static inline int huge_ptep_set_access_flags(struct vm_area_struct *vma,
 	return changed;
 }
 
-static inline void arch_clear_hugepage_flags(struct page *page)
-{
-}
-
 #include <asm-generic/hugetlb.h>
 
 #endif /* __ASM_HUGETLB_H */
diff --git a/arch/parisc/include/asm/hugetlb.h b/arch/parisc/include/asm/hugetlb.h
index 411d9d867baa..a69cf9efb0c1 100644
--- a/arch/parisc/include/asm/hugetlb.h
+++ b/arch/parisc/include/asm/hugetlb.h
@@ -42,10 +42,6 @@ int huge_ptep_set_access_flags(struct vm_area_struct *vma,
 					     unsigned long addr, pte_t *ptep,
 					     pte_t pte, int dirty);
 
-static inline void arch_clear_hugepage_flags(struct page *page)
-{
-}
-
 #include <asm-generic/hugetlb.h>
 
 #endif /* _ASM_PARISC64_HUGETLB_H */
diff --git a/arch/powerpc/include/asm/hugetlb.h b/arch/powerpc/include/asm/hugetlb.h
index b167c869d72d..e6dfa63da552 100644
--- a/arch/powerpc/include/asm/hugetlb.h
+++ b/arch/powerpc/include/asm/hugetlb.h
@@ -61,10 +61,6 @@ int huge_ptep_set_access_flags(struct vm_area_struct *vma,
 			       unsigned long addr, pte_t *ptep,
 			       pte_t pte, int dirty);
 
-static inline void arch_clear_hugepage_flags(struct page *page)
-{
-}
-
 #include <asm-generic/hugetlb.h>
 
 #else /* ! CONFIG_HUGETLB_PAGE */
diff --git a/arch/riscv/include/asm/hugetlb.h b/arch/riscv/include/asm/hugetlb.h
index 866f6ae6467c..a5c2ca1d1cd8 100644
--- a/arch/riscv/include/asm/hugetlb.h
+++ b/arch/riscv/include/asm/hugetlb.h
@@ -5,8 +5,4 @@
 #include <asm-generic/hugetlb.h>
 #include <asm/page.h>
 
-static inline void arch_clear_hugepage_flags(struct page *page)
-{
-}
-
 #endif /* _ASM_RISCV_HUGETLB_H */
diff --git a/arch/s390/include/asm/hugetlb.h b/arch/s390/include/asm/hugetlb.h
index 7d27ea96ec2f..9ddf4a43a590 100644
--- a/arch/s390/include/asm/hugetlb.h
+++ b/arch/s390/include/asm/hugetlb.h
@@ -39,6 +39,7 @@ static inline void arch_clear_hugepage_flags(struct page *page)
 {
 	clear_bit(PG_arch_1, &page->flags);
 }
+#define arch_clear_hugepage_flags arch_clear_hugepage_flags
 
 static inline void huge_pte_clear(struct mm_struct *mm, unsigned long addr,
 				  pte_t *ptep, unsigned long sz)
diff --git a/arch/sh/include/asm/hugetlb.h b/arch/sh/include/asm/hugetlb.h
index 536ad2cb8aa4..ae4de7b89210 100644
--- a/arch/sh/include/asm/hugetlb.h
+++ b/arch/sh/include/asm/hugetlb.h
@@ -30,6 +30,7 @@ static inline void arch_clear_hugepage_flags(struct page *page)
 {
 	clear_bit(PG_dcache_clean, &page->flags);
 }
+#define arch_clear_hugepage_flags arch_clear_hugepage_flags
 
 #include <asm-generic/hugetlb.h>
 
diff --git a/arch/sparc/include/asm/hugetlb.h b/arch/sparc/include/asm/hugetlb.h
index a056fe1119f5..53838a173f62 100644
--- a/arch/sparc/include/asm/hugetlb.h
+++ b/arch/sparc/include/asm/hugetlb.h
@@ -47,10 +47,6 @@ static inline int huge_ptep_set_access_flags(struct vm_area_struct *vma,
 	return changed;
 }
 
-static inline void arch_clear_hugepage_flags(struct page *page)
-{
-}
-
 #define __HAVE_ARCH_HUGETLB_FREE_PGD_RANGE
 void hugetlb_free_pgd_range(struct mmu_gather *tlb, unsigned long addr,
 			    unsigned long end, unsigned long floor,
diff --git a/arch/x86/include/asm/hugetlb.h b/arch/x86/include/asm/hugetlb.h
index cc98f79074d0..1721b1aadeb1 100644
--- a/arch/x86/include/asm/hugetlb.h
+++ b/arch/x86/include/asm/hugetlb.h
@@ -7,8 +7,4 @@
 
 #define hugepages_supported() boot_cpu_has(X86_FEATURE_PSE)
 
-static inline void arch_clear_hugepage_flags(struct page *page)
-{
-}
-
 #endif /* _ASM_X86_HUGETLB_H */
diff --git a/include/linux/hugetlb.h b/include/linux/hugetlb.h
index c01c0c6f7fd4..04bc794becfc 100644
--- a/include/linux/hugetlb.h
+++ b/include/linux/hugetlb.h
@@ -600,6 +600,11 @@ static inline int is_hugepage_only_range(struct mm_struct *mm,
 #define is_hugepage_only_range is_hugepage_only_range
 #endif
 
+#ifndef arch_clear_hugepage_flags
+static inline void arch_clear_hugepage_flags(struct page *page) { }
+#define arch_clear_hugepage_flags arch_clear_hugepage_flags
+#endif
+
 #ifndef arch_make_huge_pte
 static inline pte_t arch_make_huge_pte(pte_t entry, struct vm_area_struct *vma,
 				       struct page *page, int writable)
-- 
2.20.1


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Re: [PATCH V3 3/3] mm/hugetlb: Define a generic fallback for arch_clear_hugepage_flags()

[Mike Kravetz]

On 5/7/20 8:07 PM, Anshuman Khandual wrote:
> There are multiple similar definitions for arch_clear_hugepage_flags() on
> various platforms. Lets just add it's generic fallback definition for
> platforms that do not override. This help reduce code duplication.
> 
> Cc: Russell King <linux@armlinux.org.uk>
> Cc: Catalin Marinas <catalin.marinas@arm.com>
> Cc: Will Deacon <will@kernel.org>
> Cc: Tony Luck <tony.luck@intel.com>
> Cc: Fenghua Yu <fenghua.yu@intel.com>
> Cc: Thomas Bogendoerfer <tsbogend@alpha.franken.de>
> Cc: "James E.J. Bottomley" <James.Bottomley@HansenPartnership.com>
> Cc: Helge Deller <deller@gmx.de>
> Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
> Cc: Paul Mackerras <paulus@samba.org>
> Cc: Michael Ellerman <mpe@ellerman.id.au>
> Cc: Paul Walmsley <paul.walmsley@sifive.com>
> Cc: Palmer Dabbelt <palmer@dabbelt.com>
> Cc: Heiko Carstens <heiko.carstens@de.ibm.com>
> Cc: Vasily Gorbik <gor@linux.ibm.com>
> Cc: Christian Borntraeger <borntraeger@de.ibm.com>
> Cc: Yoshinori Sato <ysato@users.sourceforge.jp>
> Cc: Rich Felker <dalias@libc.org>
> Cc: "David S. Miller" <davem@davemloft.net>
> Cc: Thomas Gleixner <tglx@linutronix.de>
> Cc: Ingo Molnar <mingo@redhat.com>
> Cc: Borislav Petkov <bp@alien8.de>
> Cc: "H. Peter Anvin" <hpa@zytor.com>
> Cc: Mike Kravetz <mike.kravetz@oracle.com>
> Cc: Andrew Morton <akpm@linux-foundation.org>
> Cc: x86@kernel.org
> Cc: linux-arm-kernel@lists.infradead.org
> Cc: linux-ia64@vger.kernel.org
> Cc: linux-mips@vger.kernel.org
> Cc: linux-parisc@vger.kernel.org
> Cc: linuxppc-dev@lists.ozlabs.org
> Cc: linux-riscv@lists.infradead.org
> Cc: linux-s390@vger.kernel.org
> Cc: linux-sh@vger.kernel.org
> Cc: sparclinux@vger.kernel.org
> Cc: linux-mm@kvack.org
> Cc: linux-arch@vger.kernel.org
> Cc: linux-kernel@vger.kernel.org
> Signed-off-by: Anshuman Khandual <anshuman.khandual@arm.com>

Thanks!
Removing duplicate code is good.

Acked-by: Mike Kravetz <mike.kravetz@oracle.com>

-- 
Mike Kravetz

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