diff mbox series

[1/3] mm: change huge_ptep_clear_flush() to return the original pte

Message ID a9038435d408cd7b9defe143537de668dfdf03be.1651216964.git.baolin.wang@linux.alibaba.com (mailing list archive)
State New
Headers show
Series Fix CONT-PTE/PMD size hugetlb issue when unmapping or migrating | expand

Commit Message

Baolin Wang April 29, 2022, 8:14 a.m. UTC
It is incorrect to use ptep_clear_flush() to nuke a hugetlb page
table when unmapping or migrating a hugetlb page, and will change
to use huge_ptep_clear_flush() instead in the following patches.

So this is a preparation patch, which changes the huge_ptep_clear_flush()
to return the original pte to help to nuke a hugetlb page table.

Signed-off-by: Baolin Wang <baolin.wang@linux.alibaba.com>
---
 arch/arm64/include/asm/hugetlb.h   |  4 ++--
 arch/arm64/mm/hugetlbpage.c        | 12 +++++-------
 arch/ia64/include/asm/hugetlb.h    |  4 ++--
 arch/mips/include/asm/hugetlb.h    |  9 ++++++---
 arch/parisc/include/asm/hugetlb.h  |  4 ++--
 arch/powerpc/include/asm/hugetlb.h |  9 ++++++---
 arch/s390/include/asm/hugetlb.h    |  6 +++---
 arch/sh/include/asm/hugetlb.h      |  4 ++--
 arch/sparc/include/asm/hugetlb.h   |  4 ++--
 include/asm-generic/hugetlb.h      |  4 ++--
 10 files changed, 32 insertions(+), 28 deletions(-)

Comments

Mike Kravetz May 5, 2022, 11:15 p.m. UTC | #1
On 4/29/22 01:14, Baolin Wang wrote:
> It is incorrect to use ptep_clear_flush() to nuke a hugetlb page
> table when unmapping or migrating a hugetlb page, and will change
> to use huge_ptep_clear_flush() instead in the following patches.
> 
> So this is a preparation patch, which changes the huge_ptep_clear_flush()
> to return the original pte to help to nuke a hugetlb page table.
> 
> Signed-off-by: Baolin Wang <baolin.wang@linux.alibaba.com>
> ---
>  arch/arm64/include/asm/hugetlb.h   |  4 ++--
>  arch/arm64/mm/hugetlbpage.c        | 12 +++++-------
>  arch/ia64/include/asm/hugetlb.h    |  4 ++--
>  arch/mips/include/asm/hugetlb.h    |  9 ++++++---
>  arch/parisc/include/asm/hugetlb.h  |  4 ++--
>  arch/powerpc/include/asm/hugetlb.h |  9 ++++++---
>  arch/s390/include/asm/hugetlb.h    |  6 +++---
>  arch/sh/include/asm/hugetlb.h      |  4 ++--
>  arch/sparc/include/asm/hugetlb.h   |  4 ++--
>  include/asm-generic/hugetlb.h      |  4 ++--
>  10 files changed, 32 insertions(+), 28 deletions(-)

The above changes look straight forward.
Happy that you Cc'ed impacted arch maintainers so they can at least
have a look.

The only user of huge_ptep_clear_flush() today is hugetlb_cow/wp() in
mm/hugetlb.c.  Any reason why you did not change that code?  At least
cast the return of huge_ptep_clear_flush() to void with a comment?
Not absolutely necessary.

Acked-by: Mike Kravetz <mike.kravetz@oracle.com>
Baolin Wang May 6, 2022, 3:02 a.m. UTC | #2
On 5/6/2022 7:15 AM, Mike Kravetz wrote:
> On 4/29/22 01:14, Baolin Wang wrote:
>> It is incorrect to use ptep_clear_flush() to nuke a hugetlb page
>> table when unmapping or migrating a hugetlb page, and will change
>> to use huge_ptep_clear_flush() instead in the following patches.
>>
>> So this is a preparation patch, which changes the huge_ptep_clear_flush()
>> to return the original pte to help to nuke a hugetlb page table.
>>
>> Signed-off-by: Baolin Wang <baolin.wang@linux.alibaba.com>
>> ---
>>   arch/arm64/include/asm/hugetlb.h   |  4 ++--
>>   arch/arm64/mm/hugetlbpage.c        | 12 +++++-------
>>   arch/ia64/include/asm/hugetlb.h    |  4 ++--
>>   arch/mips/include/asm/hugetlb.h    |  9 ++++++---
>>   arch/parisc/include/asm/hugetlb.h  |  4 ++--
>>   arch/powerpc/include/asm/hugetlb.h |  9 ++++++---
>>   arch/s390/include/asm/hugetlb.h    |  6 +++---
>>   arch/sh/include/asm/hugetlb.h      |  4 ++--
>>   arch/sparc/include/asm/hugetlb.h   |  4 ++--
>>   include/asm-generic/hugetlb.h      |  4 ++--
>>   10 files changed, 32 insertions(+), 28 deletions(-)
> 
> The above changes look straight forward.
> Happy that you Cc'ed impacted arch maintainers so they can at least
> have a look.
> 
> The only user of huge_ptep_clear_flush() today is hugetlb_cow/wp() in
> mm/hugetlb.c.  Any reason why you did not change that code?  At least

Cause we did not use the return value of huge_ptep_clear_flush() in 
mm/hugetlb.c.

> cast the return of huge_ptep_clear_flush() to void with a comment?

Sure. Will add an explicit casting in next version.

> Not absolutely necessary.
> 
> Acked-by: Mike Kravetz <mike.kravetz@oracle.com>

Thanks.
diff mbox series

Patch

diff --git a/arch/arm64/include/asm/hugetlb.h b/arch/arm64/include/asm/hugetlb.h
index 1242f71..616b2ca 100644
--- a/arch/arm64/include/asm/hugetlb.h
+++ b/arch/arm64/include/asm/hugetlb.h
@@ -39,8 +39,8 @@  extern pte_t huge_ptep_get_and_clear(struct mm_struct *mm,
 extern void huge_ptep_set_wrprotect(struct mm_struct *mm,
 				    unsigned long addr, pte_t *ptep);
 #define __HAVE_ARCH_HUGE_PTEP_CLEAR_FLUSH
-extern void huge_ptep_clear_flush(struct vm_area_struct *vma,
-				  unsigned long addr, pte_t *ptep);
+extern pte_t huge_ptep_clear_flush(struct vm_area_struct *vma,
+				   unsigned long addr, pte_t *ptep);
 #define __HAVE_ARCH_HUGE_PTE_CLEAR
 extern void huge_pte_clear(struct mm_struct *mm, unsigned long addr,
 			   pte_t *ptep, unsigned long sz);
diff --git a/arch/arm64/mm/hugetlbpage.c b/arch/arm64/mm/hugetlbpage.c
index cbace1c..ca8e65c 100644
--- a/arch/arm64/mm/hugetlbpage.c
+++ b/arch/arm64/mm/hugetlbpage.c
@@ -486,19 +486,17 @@  void huge_ptep_set_wrprotect(struct mm_struct *mm,
 		set_pte_at(mm, addr, ptep, pfn_pte(pfn, hugeprot));
 }
 
-void huge_ptep_clear_flush(struct vm_area_struct *vma,
-			   unsigned long addr, pte_t *ptep)
+pte_t huge_ptep_clear_flush(struct vm_area_struct *vma,
+			    unsigned long addr, pte_t *ptep)
 {
 	size_t pgsize;
 	int ncontig;
 
-	if (!pte_cont(READ_ONCE(*ptep))) {
-		ptep_clear_flush(vma, addr, ptep);
-		return;
-	}
+	if (!pte_cont(READ_ONCE(*ptep)))
+		return ptep_clear_flush(vma, addr, ptep);
 
 	ncontig = find_num_contig(vma->vm_mm, addr, ptep, &pgsize);
-	clear_flush(vma->vm_mm, addr, ptep, pgsize, ncontig);
+	return get_clear_flush(vma->vm_mm, addr, ptep, pgsize, ncontig);
 }
 
 static int __init hugetlbpage_init(void)
diff --git a/arch/ia64/include/asm/hugetlb.h b/arch/ia64/include/asm/hugetlb.h
index 7e46ebd..65d3811 100644
--- a/arch/ia64/include/asm/hugetlb.h
+++ b/arch/ia64/include/asm/hugetlb.h
@@ -23,8 +23,8 @@  static inline int is_hugepage_only_range(struct mm_struct *mm,
 #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,
-					 unsigned long addr, pte_t *ptep)
+static inline pte_t huge_ptep_clear_flush(struct vm_area_struct *vma,
+					  unsigned long addr, pte_t *ptep)
 {
 }
 
diff --git a/arch/mips/include/asm/hugetlb.h b/arch/mips/include/asm/hugetlb.h
index c214440..fd69c88 100644
--- a/arch/mips/include/asm/hugetlb.h
+++ b/arch/mips/include/asm/hugetlb.h
@@ -43,16 +43,19 @@  static inline pte_t huge_ptep_get_and_clear(struct mm_struct *mm,
 }
 
 #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)
+static inline pte_t huge_ptep_clear_flush(struct vm_area_struct *vma,
+					  unsigned long addr, pte_t *ptep)
 {
+	pte_t pte;
+
 	/*
 	 * clear the huge pte entry firstly, so that the other smp threads will
 	 * not get old pte entry after finishing flush_tlb_page and before
 	 * setting new huge pte entry
 	 */
-	huge_ptep_get_and_clear(vma->vm_mm, addr, ptep);
+	pte = huge_ptep_get_and_clear(vma->vm_mm, addr, ptep);
 	flush_tlb_page(vma, addr);
+	return pte;
 }
 
 #define __HAVE_ARCH_HUGE_PTE_NONE
diff --git a/arch/parisc/include/asm/hugetlb.h b/arch/parisc/include/asm/hugetlb.h
index a69cf9e..25bc560 100644
--- a/arch/parisc/include/asm/hugetlb.h
+++ b/arch/parisc/include/asm/hugetlb.h
@@ -28,8 +28,8 @@  static inline int prepare_hugepage_range(struct file *file,
 }
 
 #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)
+static inline pte_t huge_ptep_clear_flush(struct vm_area_struct *vma,
+					  unsigned long addr, pte_t *ptep)
 {
 }
 
diff --git a/arch/powerpc/include/asm/hugetlb.h b/arch/powerpc/include/asm/hugetlb.h
index 6a1a1ac..8a5674f 100644
--- a/arch/powerpc/include/asm/hugetlb.h
+++ b/arch/powerpc/include/asm/hugetlb.h
@@ -43,11 +43,14 @@  static inline pte_t huge_ptep_get_and_clear(struct mm_struct *mm,
 }
 
 #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)
+static inline pte_t huge_ptep_clear_flush(struct vm_area_struct *vma,
+					  unsigned long addr, pte_t *ptep)
 {
-	huge_ptep_get_and_clear(vma->vm_mm, addr, ptep);
+	pte_t pte;
+
+	pte = huge_ptep_get_and_clear(vma->vm_mm, addr, ptep);
 	flush_hugetlb_page(vma, addr);
+	return pte;
 }
 
 #define __HAVE_ARCH_HUGE_PTEP_SET_ACCESS_FLAGS
diff --git a/arch/s390/include/asm/hugetlb.h b/arch/s390/include/asm/hugetlb.h
index 32c3fd6..f22beda 100644
--- a/arch/s390/include/asm/hugetlb.h
+++ b/arch/s390/include/asm/hugetlb.h
@@ -50,10 +50,10 @@  static inline void huge_pte_clear(struct mm_struct *mm, unsigned long addr,
 		set_pte(ptep, __pte(_SEGMENT_ENTRY_EMPTY));
 }
 
-static inline void huge_ptep_clear_flush(struct vm_area_struct *vma,
-					 unsigned long address, pte_t *ptep)
+static inline pte_t huge_ptep_clear_flush(struct vm_area_struct *vma,
+					  unsigned long address, pte_t *ptep)
 {
-	huge_ptep_get_and_clear(vma->vm_mm, address, ptep);
+	return huge_ptep_get_and_clear(vma->vm_mm, address, ptep);
 }
 
 static inline int huge_ptep_set_access_flags(struct vm_area_struct *vma,
diff --git a/arch/sh/include/asm/hugetlb.h b/arch/sh/include/asm/hugetlb.h
index ae4de7b..e727cc9 100644
--- a/arch/sh/include/asm/hugetlb.h
+++ b/arch/sh/include/asm/hugetlb.h
@@ -21,8 +21,8 @@  static inline int prepare_hugepage_range(struct file *file,
 }
 
 #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)
+static inline pte_t huge_ptep_clear_flush(struct vm_area_struct *vma,
+					  unsigned long addr, pte_t *ptep)
 {
 }
 
diff --git a/arch/sparc/include/asm/hugetlb.h b/arch/sparc/include/asm/hugetlb.h
index 53838a1..b50aa6f 100644
--- a/arch/sparc/include/asm/hugetlb.h
+++ b/arch/sparc/include/asm/hugetlb.h
@@ -21,8 +21,8 @@  pte_t huge_ptep_get_and_clear(struct mm_struct *mm, unsigned long addr,
 			      pte_t *ptep);
 
 #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)
+static inline pte_t huge_ptep_clear_flush(struct vm_area_struct *vma,
+					  unsigned long addr, pte_t *ptep)
 {
 }
 
diff --git a/include/asm-generic/hugetlb.h b/include/asm-generic/hugetlb.h
index 896f341..a57d667 100644
--- a/include/asm-generic/hugetlb.h
+++ b/include/asm-generic/hugetlb.h
@@ -84,10 +84,10 @@  static inline pte_t huge_ptep_get_and_clear(struct mm_struct *mm,
 #endif
 
 #ifndef __HAVE_ARCH_HUGE_PTEP_CLEAR_FLUSH
-static inline void huge_ptep_clear_flush(struct vm_area_struct *vma,
+static inline pte_t huge_ptep_clear_flush(struct vm_area_struct *vma,
 		unsigned long addr, pte_t *ptep)
 {
-	ptep_clear_flush(vma, addr, ptep);
+	return ptep_clear_flush(vma, addr, ptep);
 }
 #endif