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authorPeter Zijlstra <a.p.zijlstra@chello.nl>2006-09-26 02:30:59 -0400
committerLinus Torvalds <torvalds@g5.osdl.org>2006-09-26 11:48:44 -0400
commitc1e6098b23bb46e2b488fe9a26f831f867157483 (patch)
tree6bac4d3cfaab3e7153a15d1a24f9211b2de37ba6 /mm
parentedc79b2a46ed854595e40edcf3f8b37f9f14aa3f (diff)
[PATCH] mm: optimize the new mprotect() code a bit
mprotect() resets the page protections, which could result in extra write faults for those pages whose dirty state we track using write faults and are dirty already. Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Cc: Hugh Dickins <hugh@veritas.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
Diffstat (limited to 'mm')
-rw-r--r--mm/mprotect.c34
1 files changed, 24 insertions, 10 deletions
diff --git a/mm/mprotect.c b/mm/mprotect.c
index 367b7f6c0637..955f9d0e38aa 100644
--- a/mm/mprotect.c
+++ b/mm/mprotect.c
@@ -27,7 +27,8 @@
27#include <asm/tlbflush.h> 27#include <asm/tlbflush.h>
28 28
29static void change_pte_range(struct mm_struct *mm, pmd_t *pmd, 29static void change_pte_range(struct mm_struct *mm, pmd_t *pmd,
30 unsigned long addr, unsigned long end, pgprot_t newprot) 30 unsigned long addr, unsigned long end, pgprot_t newprot,
31 int dirty_accountable)
31{ 32{
32 pte_t *pte, oldpte; 33 pte_t *pte, oldpte;
33 spinlock_t *ptl; 34 spinlock_t *ptl;
@@ -42,7 +43,14 @@ static void change_pte_range(struct mm_struct *mm, pmd_t *pmd,
42 * bits by wiping the pte and then setting the new pte 43 * bits by wiping the pte and then setting the new pte
43 * into place. 44 * into place.
44 */ 45 */
45 ptent = pte_modify(ptep_get_and_clear(mm, addr, pte), newprot); 46 ptent = ptep_get_and_clear(mm, addr, pte);
47 ptent = pte_modify(ptent, newprot);
48 /*
49 * Avoid taking write faults for pages we know to be
50 * dirty.
51 */
52 if (dirty_accountable && pte_dirty(ptent))
53 ptent = pte_mkwrite(ptent);
46 set_pte_at(mm, addr, pte, ptent); 54 set_pte_at(mm, addr, pte, ptent);
47 lazy_mmu_prot_update(ptent); 55 lazy_mmu_prot_update(ptent);
48#ifdef CONFIG_MIGRATION 56#ifdef CONFIG_MIGRATION
@@ -66,7 +74,8 @@ static void change_pte_range(struct mm_struct *mm, pmd_t *pmd,
66} 74}
67 75
68static inline void change_pmd_range(struct mm_struct *mm, pud_t *pud, 76static inline void change_pmd_range(struct mm_struct *mm, pud_t *pud,
69 unsigned long addr, unsigned long end, pgprot_t newprot) 77 unsigned long addr, unsigned long end, pgprot_t newprot,
78 int dirty_accountable)
70{ 79{
71 pmd_t *pmd; 80 pmd_t *pmd;
72 unsigned long next; 81 unsigned long next;
@@ -76,12 +85,13 @@ static inline void change_pmd_range(struct mm_struct *mm, pud_t *pud,
76 next = pmd_addr_end(addr, end); 85 next = pmd_addr_end(addr, end);
77 if (pmd_none_or_clear_bad(pmd)) 86 if (pmd_none_or_clear_bad(pmd))
78 continue; 87 continue;
79 change_pte_range(mm, pmd, addr, next, newprot); 88 change_pte_range(mm, pmd, addr, next, newprot, dirty_accountable);
80 } while (pmd++, addr = next, addr != end); 89 } while (pmd++, addr = next, addr != end);
81} 90}
82 91
83static inline void change_pud_range(struct mm_struct *mm, pgd_t *pgd, 92static inline void change_pud_range(struct mm_struct *mm, pgd_t *pgd,
84 unsigned long addr, unsigned long end, pgprot_t newprot) 93 unsigned long addr, unsigned long end, pgprot_t newprot,
94 int dirty_accountable)
85{ 95{
86 pud_t *pud; 96 pud_t *pud;
87 unsigned long next; 97 unsigned long next;
@@ -91,12 +101,13 @@ static inline void change_pud_range(struct mm_struct *mm, pgd_t *pgd,
91 next = pud_addr_end(addr, end); 101 next = pud_addr_end(addr, end);
92 if (pud_none_or_clear_bad(pud)) 102 if (pud_none_or_clear_bad(pud))
93 continue; 103 continue;
94 change_pmd_range(mm, pud, addr, next, newprot); 104 change_pmd_range(mm, pud, addr, next, newprot, dirty_accountable);
95 } while (pud++, addr = next, addr != end); 105 } while (pud++, addr = next, addr != end);
96} 106}
97 107
98static void change_protection(struct vm_area_struct *vma, 108static void change_protection(struct vm_area_struct *vma,
99 unsigned long addr, unsigned long end, pgprot_t newprot) 109 unsigned long addr, unsigned long end, pgprot_t newprot,
110 int dirty_accountable)
100{ 111{
101 struct mm_struct *mm = vma->vm_mm; 112 struct mm_struct *mm = vma->vm_mm;
102 pgd_t *pgd; 113 pgd_t *pgd;
@@ -110,7 +121,7 @@ static void change_protection(struct vm_area_struct *vma,
110 next = pgd_addr_end(addr, end); 121 next = pgd_addr_end(addr, end);
111 if (pgd_none_or_clear_bad(pgd)) 122 if (pgd_none_or_clear_bad(pgd))
112 continue; 123 continue;
113 change_pud_range(mm, pgd, addr, next, newprot); 124 change_pud_range(mm, pgd, addr, next, newprot, dirty_accountable);
114 } while (pgd++, addr = next, addr != end); 125 } while (pgd++, addr = next, addr != end);
115 flush_tlb_range(vma, start, end); 126 flush_tlb_range(vma, start, end);
116} 127}
@@ -125,6 +136,7 @@ mprotect_fixup(struct vm_area_struct *vma, struct vm_area_struct **pprev,
125 unsigned long charged = 0; 136 unsigned long charged = 0;
126 pgoff_t pgoff; 137 pgoff_t pgoff;
127 int error; 138 int error;
139 int dirty_accountable = 0;
128 140
129 if (newflags == oldflags) { 141 if (newflags == oldflags) {
130 *pprev = vma; 142 *pprev = vma;
@@ -181,14 +193,16 @@ success:
181 vma->vm_flags = newflags; 193 vma->vm_flags = newflags;
182 vma->vm_page_prot = protection_map[newflags & 194 vma->vm_page_prot = protection_map[newflags &
183 (VM_READ|VM_WRITE|VM_EXEC|VM_SHARED)]; 195 (VM_READ|VM_WRITE|VM_EXEC|VM_SHARED)];
184 if (vma_wants_writenotify(vma)) 196 if (vma_wants_writenotify(vma)) {
185 vma->vm_page_prot = protection_map[newflags & 197 vma->vm_page_prot = protection_map[newflags &
186 (VM_READ|VM_WRITE|VM_EXEC)]; 198 (VM_READ|VM_WRITE|VM_EXEC)];
199 dirty_accountable = 1;
200 }
187 201
188 if (is_vm_hugetlb_page(vma)) 202 if (is_vm_hugetlb_page(vma))
189 hugetlb_change_protection(vma, start, end, vma->vm_page_prot); 203 hugetlb_change_protection(vma, start, end, vma->vm_page_prot);
190 else 204 else
191 change_protection(vma, start, end, vma->vm_page_prot); 205 change_protection(vma, start, end, vma->vm_page_prot, dirty_accountable);
192 vm_stat_account(mm, oldflags, vma->vm_file, -nrpages); 206 vm_stat_account(mm, oldflags, vma->vm_file, -nrpages);
193 vm_stat_account(mm, newflags, vma->vm_file, nrpages); 207 vm_stat_account(mm, newflags, vma->vm_file, nrpages);
194 return 0; 208 return 0;