[PATCH 06/27] mm: Count the number of pages affected in change_protection()
From: Ingo Molnar
Date: Sun Nov 18 2012 - 21:15:27 EST
From: Peter Zijlstra <a.p.zijlstra@xxxxxxxxx>
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@xxxxxxxxxx>
Signed-off-by: Peter Zijlstra <a.p.zijlstra@xxxxxxxxx>
Cc: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>
Cc: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
Cc: Andrea Arcangeli <aarcange@xxxxxxxxxx>
Cc: Rik van Riel <riel@xxxxxxxxxx>
Cc: Mel Gorman <mgorman@xxxxxxx>
Cc: Hugh Dickins <hughd@xxxxxxxxxx>
Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Signed-off-by: Ingo Molnar <mingo@xxxxxxxxxx>
---
include/linux/hugetlb.h | 8 +++++--
include/linux/mm.h | 3 +++
mm/hugetlb.c | 10 +++++++--
mm/mprotect.c | 58 +++++++++++++++++++++++++++++++++++++------------
4 files changed, 61 insertions(+), 18 deletions(-)
diff --git a/include/linux/hugetlb.h b/include/linux/hugetlb.h
index 2251648..06e691b 100644
--- a/include/linux/hugetlb.h
+++ b/include/linux/hugetlb.h
@@ -87,7 +87,7 @@ struct page *follow_huge_pud(struct mm_struct *mm, unsigned long address,
pud_t *pud, int write);
int pmd_huge(pmd_t pmd);
int pud_huge(pud_t pmd);
-void hugetlb_change_protection(struct vm_area_struct *vma,
+unsigned long hugetlb_change_protection(struct vm_area_struct *vma,
unsigned long address, unsigned long end, pgprot_t newprot);
#else /* !CONFIG_HUGETLB_PAGE */
@@ -132,7 +132,11 @@ static inline void copy_huge_page(struct page *dst, struct page *src)
{
}
-#define hugetlb_change_protection(vma, address, end, newprot)
+static inline unsigned long hugetlb_change_protection(struct vm_area_struct *vma,
+ unsigned long address, unsigned long end, pgprot_t newprot)
+{
+ return 0;
+}
static inline void __unmap_hugepage_range_final(struct mmu_gather *tlb,
struct vm_area_struct *vma, unsigned long start,
diff --git a/include/linux/mm.h b/include/linux/mm.h
index fa06804..8d86d5a 100644
--- a/include/linux/mm.h
+++ b/include/linux/mm.h
@@ -1078,6 +1078,9 @@ extern unsigned long move_page_tables(struct vm_area_struct *vma,
extern unsigned long do_mremap(unsigned long addr,
unsigned long old_len, unsigned long new_len,
unsigned long flags, unsigned long new_addr);
+extern unsigned long change_protection(struct vm_area_struct *vma, unsigned long start,
+ unsigned long end, pgprot_t newprot,
+ int dirty_accountable);
extern int mprotect_fixup(struct vm_area_struct *vma,
struct vm_area_struct **pprev, unsigned long start,
unsigned long end, unsigned long newflags);
diff --git a/mm/hugetlb.c b/mm/hugetlb.c
index 59a0059..712895e 100644
--- a/mm/hugetlb.c
+++ b/mm/hugetlb.c
@@ -3014,7 +3014,7 @@ same_page:
return i ? i : -EFAULT;
}
-void hugetlb_change_protection(struct vm_area_struct *vma,
+unsigned long hugetlb_change_protection(struct vm_area_struct *vma,
unsigned long address, unsigned long end, pgprot_t newprot)
{
struct mm_struct *mm = vma->vm_mm;
@@ -3022,6 +3022,7 @@ void hugetlb_change_protection(struct vm_area_struct *vma,
pte_t *ptep;
pte_t pte;
struct hstate *h = hstate_vma(vma);
+ unsigned long pages = 0;
BUG_ON(address >= end);
flush_cache_range(vma, address, end);
@@ -3032,12 +3033,15 @@ void hugetlb_change_protection(struct vm_area_struct *vma,
ptep = huge_pte_offset(mm, address);
if (!ptep)
continue;
- if (huge_pmd_unshare(mm, &address, ptep))
+ if (huge_pmd_unshare(mm, &address, ptep)) {
+ pages++;
continue;
+ }
if (!huge_pte_none(huge_ptep_get(ptep))) {
pte = huge_ptep_get_and_clear(mm, address, ptep);
pte = pte_mkhuge(pte_modify(pte, newprot));
set_huge_pte_at(mm, address, ptep, pte);
+ pages++;
}
}
spin_unlock(&mm->page_table_lock);
@@ -3049,6 +3053,8 @@ void hugetlb_change_protection(struct vm_area_struct *vma,
*/
flush_tlb_range(vma, start, end);
mutex_unlock(&vma->vm_file->f_mapping->i_mmap_mutex);
+
+ return pages << h->order;
}
int hugetlb_reserve_pages(struct inode *inode,
diff --git a/mm/mprotect.c b/mm/mprotect.c
index a409926..1e265be 100644
--- a/mm/mprotect.c
+++ b/mm/mprotect.c
@@ -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);
--
1.7.11.7
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