[PATCH 2/3] mm/mprotect: Use long for page accountings and retval
From: Peter Xu
Date: Wed Jan 04 2023 - 17:56:58 EST
Switch to use type "long" for page accountings and retval across the whole
procedure of change_protection().
The change should have shrinked the possible maximum page number to be half
comparing to previous (ULONG_MAX / 2), but it shouldn't overflow on any
system either because the maximum possible pages touched by change
protection should be ULONG_MAX / PAGE_SIZE.
Two reasons to switch from "unsigned long" to "long":
1. It suites better on count_vm_numa_events(), whose 2nd parameter takes
a long type.
2. It paves way for returning negative (error) values in the future.
Currently the only caller that consumes this retval is change_prot_numa(),
where the unsigned long was converted to an int. Since at it, touching up
the numa code to also take a long, so it'll avoid any possible overflow too
during the int-size convertion.
Signed-off-by: Peter Xu <peterx@xxxxxxxxxx>
---
include/linux/hugetlb.h | 4 ++--
include/linux/mm.h | 2 +-
mm/hugetlb.c | 4 ++--
mm/mempolicy.c | 2 +-
mm/mprotect.c | 26 +++++++++++++-------------
5 files changed, 19 insertions(+), 19 deletions(-)
diff --git a/include/linux/hugetlb.h b/include/linux/hugetlb.h
index b6b10101bea7..e3aa336df900 100644
--- a/include/linux/hugetlb.h
+++ b/include/linux/hugetlb.h
@@ -248,7 +248,7 @@ void hugetlb_vma_lock_release(struct kref *kref);
int pmd_huge(pmd_t pmd);
int pud_huge(pud_t pud);
-unsigned long hugetlb_change_protection(struct vm_area_struct *vma,
+long hugetlb_change_protection(struct vm_area_struct *vma,
unsigned long address, unsigned long end, pgprot_t newprot,
unsigned long cp_flags);
@@ -437,7 +437,7 @@ static inline void move_hugetlb_state(struct folio *old_folio,
{
}
-static inline unsigned long hugetlb_change_protection(
+static inline long hugetlb_change_protection(
struct vm_area_struct *vma, unsigned long address,
unsigned long end, pgprot_t newprot,
unsigned long cp_flags)
diff --git a/include/linux/mm.h b/include/linux/mm.h
index c37f9330f14e..86fe17e6ded7 100644
--- a/include/linux/mm.h
+++ b/include/linux/mm.h
@@ -2132,7 +2132,7 @@ static inline bool vma_wants_manual_pte_write_upgrade(struct vm_area_struct *vma
}
bool can_change_pte_writable(struct vm_area_struct *vma, unsigned long addr,
pte_t pte);
-extern unsigned long change_protection(struct mmu_gather *tlb,
+extern long change_protection(struct mmu_gather *tlb,
struct vm_area_struct *vma, unsigned long start,
unsigned long end, unsigned long cp_flags);
extern int mprotect_fixup(struct mmu_gather *tlb, struct vm_area_struct *vma,
diff --git a/mm/hugetlb.c b/mm/hugetlb.c
index 017d9159cddf..84bc665c7c86 100644
--- a/mm/hugetlb.c
+++ b/mm/hugetlb.c
@@ -6613,7 +6613,7 @@ long follow_hugetlb_page(struct mm_struct *mm, struct vm_area_struct *vma,
return i ? i : err;
}
-unsigned long hugetlb_change_protection(struct vm_area_struct *vma,
+long hugetlb_change_protection(struct vm_area_struct *vma,
unsigned long address, unsigned long end,
pgprot_t newprot, unsigned long cp_flags)
{
@@ -6622,7 +6622,7 @@ unsigned long hugetlb_change_protection(struct vm_area_struct *vma,
pte_t *ptep;
pte_t pte;
struct hstate *h = hstate_vma(vma);
- unsigned long pages = 0, psize = huge_page_size(h);
+ long pages = 0, psize = huge_page_size(h);
bool shared_pmd = false;
struct mmu_notifier_range range;
unsigned long last_addr_mask;
diff --git a/mm/mempolicy.c b/mm/mempolicy.c
index d3558248a0f0..a86b8f15e2f0 100644
--- a/mm/mempolicy.c
+++ b/mm/mempolicy.c
@@ -631,7 +631,7 @@ unsigned long change_prot_numa(struct vm_area_struct *vma,
unsigned long addr, unsigned long end)
{
struct mmu_gather tlb;
- int nr_updated;
+ long nr_updated;
tlb_gather_mmu(&tlb, vma->vm_mm);
diff --git a/mm/mprotect.c b/mm/mprotect.c
index 71358e45a742..0af22ab59ea8 100644
--- a/mm/mprotect.c
+++ b/mm/mprotect.c
@@ -80,13 +80,13 @@ bool can_change_pte_writable(struct vm_area_struct *vma, unsigned long addr,
return pte_dirty(pte);
}
-static unsigned long change_pte_range(struct mmu_gather *tlb,
+static long change_pte_range(struct mmu_gather *tlb,
struct vm_area_struct *vma, pmd_t *pmd, unsigned long addr,
unsigned long end, pgprot_t newprot, unsigned long cp_flags)
{
pte_t *pte, oldpte;
spinlock_t *ptl;
- unsigned long pages = 0;
+ long pages = 0;
int target_node = NUMA_NO_NODE;
bool prot_numa = cp_flags & MM_CP_PROT_NUMA;
bool uffd_wp = cp_flags & MM_CP_UFFD_WP;
@@ -353,13 +353,13 @@ uffd_wp_protect_file(struct vm_area_struct *vma, unsigned long cp_flags)
} \
} while (0)
-static inline unsigned long change_pmd_range(struct mmu_gather *tlb,
+static inline long change_pmd_range(struct mmu_gather *tlb,
struct vm_area_struct *vma, pud_t *pud, unsigned long addr,
unsigned long end, pgprot_t newprot, unsigned long cp_flags)
{
pmd_t *pmd;
unsigned long next;
- unsigned long pages = 0;
+ long pages = 0;
unsigned long nr_huge_updates = 0;
struct mmu_notifier_range range;
@@ -367,7 +367,7 @@ static inline unsigned long change_pmd_range(struct mmu_gather *tlb,
pmd = pmd_offset(pud, addr);
do {
- unsigned long this_pages;
+ long this_pages;
next = pmd_addr_end(addr, end);
@@ -437,13 +437,13 @@ static inline unsigned long change_pmd_range(struct mmu_gather *tlb,
return pages;
}
-static inline unsigned long change_pud_range(struct mmu_gather *tlb,
+static inline long change_pud_range(struct mmu_gather *tlb,
struct vm_area_struct *vma, p4d_t *p4d, unsigned long addr,
unsigned long end, pgprot_t newprot, unsigned long cp_flags)
{
pud_t *pud;
unsigned long next;
- unsigned long pages = 0;
+ long pages = 0;
pud = pud_offset(p4d, addr);
do {
@@ -458,13 +458,13 @@ static inline unsigned long change_pud_range(struct mmu_gather *tlb,
return pages;
}
-static inline unsigned long change_p4d_range(struct mmu_gather *tlb,
+static inline long change_p4d_range(struct mmu_gather *tlb,
struct vm_area_struct *vma, pgd_t *pgd, unsigned long addr,
unsigned long end, pgprot_t newprot, unsigned long cp_flags)
{
p4d_t *p4d;
unsigned long next;
- unsigned long pages = 0;
+ long pages = 0;
p4d = p4d_offset(pgd, addr);
do {
@@ -479,14 +479,14 @@ static inline unsigned long change_p4d_range(struct mmu_gather *tlb,
return pages;
}
-static unsigned long change_protection_range(struct mmu_gather *tlb,
+static long change_protection_range(struct mmu_gather *tlb,
struct vm_area_struct *vma, unsigned long addr,
unsigned long end, pgprot_t newprot, unsigned long cp_flags)
{
struct mm_struct *mm = vma->vm_mm;
pgd_t *pgd;
unsigned long next;
- unsigned long pages = 0;
+ long pages = 0;
BUG_ON(addr >= end);
pgd = pgd_offset(mm, addr);
@@ -505,12 +505,12 @@ static unsigned long change_protection_range(struct mmu_gather *tlb,
return pages;
}
-unsigned long change_protection(struct mmu_gather *tlb,
+long change_protection(struct mmu_gather *tlb,
struct vm_area_struct *vma, unsigned long start,
unsigned long end, unsigned long cp_flags)
{
pgprot_t newprot = vma->vm_page_prot;
- unsigned long pages;
+ long pages;
BUG_ON((cp_flags & MM_CP_UFFD_WP_ALL) == MM_CP_UFFD_WP_ALL);
--
2.37.3