[PATCH v2 1/3] mm: change huge_ptep_clear_flush() to return the original pte

Baolin Wang
2022-05-08T09:36:39Z

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>
Acked-by: Mike Kravetz <mike.kravetz@oracle.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 ++--
mm/hugetlb.c | 2 +-
11 files changed, 33 insertions(+), 29 deletions(-)

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

diff --git a/mm/hugetlb.c b/mm/hugetlb.c
index 8605d7e..61a21af 100644
--- a/mm/hugetlb.c
+++ b/mm/hugetlb.c
@@ -5342,7 +5342,7 @@ static vm_fault_t hugetlb_wp(struct mm_struct *mm, struct vm_area_struct *vma,
ClearHPageRestoreReserve(new_page);

/* Break COW or unshare */
- huge_ptep_clear_flush(vma, haddr, ptep);
+ (void)huge_ptep_clear_flush(vma, haddr, ptep);
mmu_notifier_invalidate_range(mm, range.start, range.end);
page_remove_rmap(old_page, vma, true);
hugepage_add_new_anon_rmap(new_page, vma, haddr);
--
1.8.3.1