From a79390f5d6a78647fd70856bd42b22d994de0ba2 Mon Sep 17 00:00:00 2001 From: Peter Xu Date: Wed, 4 Jan 2023 17:52:06 -0500 Subject: 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: Peter Xu Acked-by: Mike Kravetz Acked-by: James Houghton Cc: Andrea Arcangeli Cc: Axel Rasmussen Cc: David Hildenbrand Cc: Muchun Song Cc: Nadav Amit Signed-off-by: Andrew Morton --- mm/mprotect.c | 26 +++++++++++++------------- 1 file changed, 13 insertions(+), 13 deletions(-) (limited to 'mm/mprotect.c') 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 @@ next: 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); -- cgit