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mm: Count the number of pages affected in change_protection()

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This will be used for three kinds of purposes:

 - to optimize mprotect()

 - to speed up working set scanning for working set areas that
   have not been touched

 - to more accurately scan per real working set

No change in functionality from this patch.

Suggested-by: Ingo Molnar <mingo@kernel.org>
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Rik van Riel <riel@redhat.com>
Cc: Mel Gorman <mgorman@suse.de>
Cc: Hugh Dickins <hughd@google.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
This commit is contained in:
Peter Zijlstra
2012-11-19 03:14:23 +01:00
committed by Mel Gorman
parent 4fd017708c
commit 7da4d641c5
4 changed files with 61 additions and 18 deletions
Download Patch File Download Diff File Expand all files Collapse all files
mm/mprotect.c
+44 -14
View File
@@ -35,12 +35,13 @@ static inline pgprot_t pgprot_modify(pgprot_t oldprot, pgprot_t newprot)
}
#endif
static void change_pte_range(struct mm_struct *mm, pmd_t *pmd,
static unsigned long change_pte_range(struct mm_struct *mm, pmd_t *pmd,
unsigned long addr, unsigned long end, pgprot_t newprot,
int dirty_accountable)
{
pte_t *pte, oldpte;
spinlock_t *ptl;
unsigned long pages = 0;
pte = pte_offset_map_lock(mm, pmd, addr, &ptl);
arch_enter_lazy_mmu_mode();
@@ -60,6 +61,7 @@ static void change_pte_range(struct mm_struct *mm, pmd_t *pmd,
ptent = pte_mkwrite(ptent);
ptep_modify_prot_commit(mm, addr, pte, ptent);
pages++;
} else if (IS_ENABLED(CONFIG_MIGRATION) && !pte_file(oldpte)) {
swp_entry_t entry = pte_to_swp_entry(oldpte);
@@ -72,18 +74,22 @@ static void change_pte_range(struct mm_struct *mm, pmd_t *pmd,
set_pte_at(mm, addr, pte,
swp_entry_to_pte(entry));
}
pages++;
}
} while (pte++, addr += PAGE_SIZE, addr != end);
arch_leave_lazy_mmu_mode();
pte_unmap_unlock(pte - 1, ptl);
return pages;
}
static inline void change_pmd_range(struct vm_area_struct *vma, pud_t *pud,
static inline unsigned long change_pmd_range(struct vm_area_struct *vma, pud_t *pud,
unsigned long addr, unsigned long end, pgprot_t newprot,
int dirty_accountable)
{
pmd_t *pmd;
unsigned long next;
unsigned long pages = 0;
pmd = pmd_offset(pud, addr);
do {
@@ -91,35 +97,42 @@ static inline void change_pmd_range(struct vm_area_struct *vma, pud_t *pud,
if (pmd_trans_huge(*pmd)) {
if (next - addr != HPAGE_PMD_SIZE)
split_huge_page_pmd(vma->vm_mm, pmd);
else if (change_huge_pmd(vma, pmd, addr, newprot))
else if (change_huge_pmd(vma, pmd, addr, newprot)) {
pages += HPAGE_PMD_NR;
continue;
}
/* fall through */
}
if (pmd_none_or_clear_bad(pmd))
continue;
change_pte_range(vma->vm_mm, pmd, addr, next, newprot,
pages += change_pte_range(vma->vm_mm, pmd, addr, next, newprot,
dirty_accountable);
} while (pmd++, addr = next, addr != end);
return pages;
}
static inline void change_pud_range(struct vm_area_struct *vma, pgd_t *pgd,
static inline unsigned long change_pud_range(struct vm_area_struct *vma, pgd_t *pgd,
unsigned long addr, unsigned long end, pgprot_t newprot,
int dirty_accountable)
{
pud_t *pud;
unsigned long next;
unsigned long pages = 0;
pud = pud_offset(pgd, addr);
do {
next = pud_addr_end(addr, end);
if (pud_none_or_clear_bad(pud))
continue;
change_pmd_range(vma, pud, addr, next, newprot,
pages += change_pmd_range(vma, pud, addr, next, newprot,
dirty_accountable);
} while (pud++, addr = next, addr != end);
return pages;
}
static void change_protection(struct vm_area_struct *vma,
static unsigned long change_protection_range(struct vm_area_struct *vma,
unsigned long addr, unsigned long end, pgprot_t newprot,
int dirty_accountable)
{
@@ -127,6 +140,7 @@ static void change_protection(struct vm_area_struct *vma,
pgd_t *pgd;
unsigned long next;
unsigned long start = addr;
unsigned long pages = 0;
BUG_ON(addr >= end);
pgd = pgd_offset(mm, addr);
@@ -135,10 +149,30 @@ static void change_protection(struct vm_area_struct *vma,
next = pgd_addr_end(addr, end);
if (pgd_none_or_clear_bad(pgd))
continue;
change_pud_range(vma, pgd, addr, next, newprot,
pages += change_pud_range(vma, pgd, addr, next, newprot,
dirty_accountable);
} while (pgd++, addr = next, addr != end);
flush_tlb_range(vma, start, end);
return pages;
}
unsigned long change_protection(struct vm_area_struct *vma, unsigned long start,
unsigned long end, pgprot_t newprot,
int dirty_accountable)
{
struct mm_struct *mm = vma->vm_mm;
unsigned long pages;
mmu_notifier_invalidate_range_start(mm, start, end);
if (is_vm_hugetlb_page(vma))
pages = hugetlb_change_protection(vma, start, end, newprot);
else
pages = change_protection_range(vma, start, end, newprot, dirty_accountable);
mmu_notifier_invalidate_range_end(mm, start, end);
return pages;
}
int
@@ -213,12 +247,8 @@ success:
dirty_accountable = 1;
}
mmu_notifier_invalidate_range_start(mm, start, end);
if (is_vm_hugetlb_page(vma))
hugetlb_change_protection(vma, start, end, vma->vm_page_prot);
else
change_protection(vma, start, end, vma->vm_page_prot, dirty_accountable);
mmu_notifier_invalidate_range_end(mm, start, end);
change_protection(vma, start, end, vma->vm_page_prot, dirty_accountable);
vm_stat_account(mm, oldflags, vma->vm_file, -nrpages);
vm_stat_account(mm, newflags, vma->vm_file, nrpages);
perf_event_mmap(vma);