From 89c4e30ce0887c6520c5b1f4921a9c173d8fe2bc Mon Sep 17 00:00:00 2001
From: Peter Zijlstra <a.p.zijlstra@chello.nl>
Date: Mon, 25 Sep 2006 23:30:59 -0700
Subject: [PATCH] --- yaml --- r: 35567 b: refs/heads/master c:
 c1e6098b23bb46e2b488fe9a26f831f867157483 h: refs/heads/master i:   35565:
 4f376da659d674784cf32731203fc77647c3bf91   35563:
 45ef7f9342373fee20a51e6a9cf88de35b56a7f3   35559:
 84572bf047a090a428758564da1bbc0fa8736350   35551:
 4ad46721a55c20e1d4f689e6576c0d5294d056d2 v: v3

---
 [refs]              |  2 +-
 trunk/mm/mprotect.c | 34 ++++++++++++++++++++++++----------
 2 files changed, 25 insertions(+), 11 deletions(-)

diff --git a/[refs] b/[refs]
index 339c2ee9bdd3..a0680a43f642 100644
--- a/[refs]
+++ b/[refs]
@@ -1,2 +1,2 @@
 ---
-refs/heads/master: edc79b2a46ed854595e40edcf3f8b37f9f14aa3f
+refs/heads/master: c1e6098b23bb46e2b488fe9a26f831f867157483
diff --git a/trunk/mm/mprotect.c b/trunk/mm/mprotect.c
index 367b7f6c0637..955f9d0e38aa 100644
--- a/trunk/mm/mprotect.c
+++ b/trunk/mm/mprotect.c
@@ -27,7 +27,8 @@
 #include <asm/tlbflush.h>
 
 static void change_pte_range(struct mm_struct *mm, pmd_t *pmd,
-		unsigned long addr, unsigned long end, pgprot_t newprot)
+		unsigned long addr, unsigned long end, pgprot_t newprot,
+		int dirty_accountable)
 {
 	pte_t *pte, oldpte;
 	spinlock_t *ptl;
@@ -42,7 +43,14 @@ static void change_pte_range(struct mm_struct *mm, pmd_t *pmd,
 			 * bits by wiping the pte and then setting the new pte
 			 * into place.
 			 */
-			ptent = pte_modify(ptep_get_and_clear(mm, addr, pte), newprot);
+			ptent = ptep_get_and_clear(mm, addr, pte);
+			ptent = pte_modify(ptent, newprot);
+			/*
+			 * Avoid taking write faults for pages we know to be
+			 * dirty.
+			 */
+			if (dirty_accountable && pte_dirty(ptent))
+				ptent = pte_mkwrite(ptent);
 			set_pte_at(mm, addr, pte, ptent);
 			lazy_mmu_prot_update(ptent);
 #ifdef CONFIG_MIGRATION
@@ -66,7 +74,8 @@ static void change_pte_range(struct mm_struct *mm, pmd_t *pmd,
 }
 
 static inline void change_pmd_range(struct mm_struct *mm, pud_t *pud,
-		unsigned long addr, unsigned long end, pgprot_t newprot)
+		unsigned long addr, unsigned long end, pgprot_t newprot,
+		int dirty_accountable)
 {
 	pmd_t *pmd;
 	unsigned long next;
@@ -76,12 +85,13 @@ static inline void change_pmd_range(struct mm_struct *mm, pud_t *pud,
 		next = pmd_addr_end(addr, end);
 		if (pmd_none_or_clear_bad(pmd))
 			continue;
-		change_pte_range(mm, pmd, addr, next, newprot);
+		change_pte_range(mm, pmd, addr, next, newprot, dirty_accountable);
 	} while (pmd++, addr = next, addr != end);
 }
 
 static inline void change_pud_range(struct mm_struct *mm, pgd_t *pgd,
-		unsigned long addr, unsigned long end, pgprot_t newprot)
+		unsigned long addr, unsigned long end, pgprot_t newprot,
+		int dirty_accountable)
 {
 	pud_t *pud;
 	unsigned long next;
@@ -91,12 +101,13 @@ static inline void change_pud_range(struct mm_struct *mm, pgd_t *pgd,
 		next = pud_addr_end(addr, end);
 		if (pud_none_or_clear_bad(pud))
 			continue;
-		change_pmd_range(mm, pud, addr, next, newprot);
+		change_pmd_range(mm, pud, addr, next, newprot, dirty_accountable);
 	} while (pud++, addr = next, addr != end);
 }
 
 static void change_protection(struct vm_area_struct *vma,
-		unsigned long addr, unsigned long end, pgprot_t newprot)
+		unsigned long addr, unsigned long end, pgprot_t newprot,
+		int dirty_accountable)
 {
 	struct mm_struct *mm = vma->vm_mm;
 	pgd_t *pgd;
@@ -110,7 +121,7 @@ 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(mm, pgd, addr, next, newprot);
+		change_pud_range(mm, pgd, addr, next, newprot, dirty_accountable);
 	} while (pgd++, addr = next, addr != end);
 	flush_tlb_range(vma, start, end);
 }
@@ -125,6 +136,7 @@ mprotect_fixup(struct vm_area_struct *vma, struct vm_area_struct **pprev,
 	unsigned long charged = 0;
 	pgoff_t pgoff;
 	int error;
+	int dirty_accountable = 0;
 
 	if (newflags == oldflags) {
 		*pprev = vma;
@@ -181,14 +193,16 @@ mprotect_fixup(struct vm_area_struct *vma, struct vm_area_struct **pprev,
 	vma->vm_flags = newflags;
 	vma->vm_page_prot = protection_map[newflags &
 		(VM_READ|VM_WRITE|VM_EXEC|VM_SHARED)];
-	if (vma_wants_writenotify(vma))
+	if (vma_wants_writenotify(vma)) {
 		vma->vm_page_prot = protection_map[newflags &
 			(VM_READ|VM_WRITE|VM_EXEC)];
+		dirty_accountable = 1;
+	}
 
 	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);
+		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);
 	return 0;