Merge with /pub/scm/linux/kernel/git/torvalds/linux-2.6.git

1 files changed, 21 insertions, 25 deletions

diff --git a/mm/memory.c b/mm/memory.c
index beabdefa6254..2405289dfdf8 100644
--- a/mm/memory.c
+++ b/mm/memory.c
@@ -776,8 +776,8 @@ unsigned long zap_page_range(struct vm_area_struct *vma, unsigned long address,
  * Do a quick page-table lookup for a single page.
  * mm->page_table_lock must be held.
  */
-static struct page *
-__follow_page(struct mm_struct *mm, unsigned long address, int read, int write)
+static struct page *__follow_page(struct mm_struct *mm, unsigned long address,
+			int read, int write, int accessed)
 {
 	pgd_t *pgd;
 	pud_t *pud;
@@ -811,16 +811,15 @@ __follow_page(struct mm_struct *mm, unsigned long address, int read, int write)
 	pte = *ptep;
 	pte_unmap(ptep);
 	if (pte_present(pte)) {
-		if (write && !pte_write(pte))
+		if (write && !pte_dirty(pte))
 			goto out;
 		if (read && !pte_read(pte))
 			goto out;
 		pfn = pte_pfn(pte);
 		if (pfn_valid(pfn)) {
 			page = pfn_to_page(pfn);
-			if (write && !pte_dirty(pte) && !PageDirty(page))
-				set_page_dirty(page);
-			mark_page_accessed(page);
+			if (accessed)
+				mark_page_accessed(page);
 			return page;
 		}
 	}
@@ -829,16 +828,19 @@ out:
 	return NULL;
 }
 
-struct page *
+inline struct page *
 follow_page(struct mm_struct *mm, unsigned long address, int write)
 {
-	return __follow_page(mm, address, /*read*/0, write);
+	return __follow_page(mm, address, 0, write, 1);
 }
 
-int
-check_user_page_readable(struct mm_struct *mm, unsigned long address)
+/*
+ * check_user_page_readable() can be called frm niterrupt context by oprofile,
+ * so we need to avoid taking any non-irq-safe locks
+ */
+int check_user_page_readable(struct mm_struct *mm, unsigned long address)
 {
-	return __follow_page(mm, address, /*read*/1, /*write*/0) != NULL;
+	return __follow_page(mm, address, 1, 0, 0) != NULL;
 }
 EXPORT_SYMBOL(check_user_page_readable);
 
@@ -908,9 +910,13 @@ int get_user_pages(struct task_struct *tsk, struct mm_struct *mm,
 			pud = pud_offset(pgd, pg);
 			BUG_ON(pud_none(*pud));
 			pmd = pmd_offset(pud, pg);
-			BUG_ON(pmd_none(*pmd));
+			if (pmd_none(*pmd))
+				return i ? : -EFAULT;
 			pte = pte_offset_map(pmd, pg);
-			BUG_ON(pte_none(*pte));
+			if (pte_none(*pte)) {
+				pte_unmap(pte);
+				return i ? : -EFAULT;
+			}
 			if (pages) {
 				pages[i] = pte_page(*pte);
 				get_page(pages[i]);
@@ -936,10 +942,9 @@ int get_user_pages(struct task_struct *tsk, struct mm_struct *mm,
 		spin_lock(&mm->page_table_lock);
 		do {
 			struct page *page;
-			int lookup_write = write;
 
 			cond_resched_lock(&mm->page_table_lock);
-			while (!(page = follow_page(mm, start, lookup_write))) {
+			while (!(page = follow_page(mm, start, write))) {
 				/*
 				 * Shortcut for anonymous pages. We don't want
 				 * to force the creation of pages tables for
@@ -947,8 +952,7 @@ int get_user_pages(struct task_struct *tsk, struct mm_struct *mm,
 				 * nobody touched so far. This is important
 				 * for doing a core dump for these mappings.
 				 */
-				if (!lookup_write &&
-				    untouched_anonymous_page(mm,vma,start)) {
+				if (!write && untouched_anonymous_page(mm,vma,start)) {
 					page = ZERO_PAGE(start);
 					break;
 				}
@@ -967,14 +971,6 @@ int get_user_pages(struct task_struct *tsk, struct mm_struct *mm,
 				default:
 					BUG();
 				}
-				/*
-				 * Now that we have performed a write fault
-				 * and surely no longer have a shared page we
-				 * shouldn't write, we shouldn't ignore an
-				 * unwritable page in the page table if
-				 * we are forcing write access.
-				 */
-				lookup_write = write && !force;
 				spin_lock(&mm->page_table_lock);
 			}
 			if (pages) {