Commit a79390f5 authored by Peter Xu's avatar Peter Xu Committed by Andrew Morton
Browse files

mm/mprotect: use long for page accountings and retval 

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.

Link: https://lkml.kernel.org/r/20230104225207.1066932-3-peterx@redhat.com


Signed-off-by: default avatarPeter Xu <peterx@redhat.com>
Acked-by: default avatarMike Kravetz <mike.kravetz@oracle.com>
Acked-by: default avatarJames Houghton <jthoughton@google.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Axel Rasmussen <axelrasmussen@google.com>
Cc: David Hildenbrand <david@redhat.com>
Cc: Muchun Song <songmuchun@bytedance.com>
Cc: Nadav Amit <nadav.amit@gmail.com>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
parent 6b7cea90

include/linux/hugetlb.h

+2 −2
Original line number Diff line number Diff line
@@ -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)

include/linux/mm.h

+1 −1
Original line number Diff line number Diff line
@@ -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,

mm/hugetlb.c

+2 −2
Original line number Diff line number Diff line
@@ -6615,7 +6615,7 @@ 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)

{
@@ -6624,7 +6624,7 @@ 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;

mm/mempolicy.c

+1 −1
Original line number Diff line number Diff line
@@ -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);

mm/mprotect.c

+13 −13
Original line number Diff line number Diff line
@@ -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);