X-Git-Url: https://err.no/cgi-bin/gitweb.cgi?a=blobdiff_plain;f=mm%2Fmemory.c;h=4e1c673784dbbe67a19ea9b95c998ca6cd019893;hb=4ceb5db9757aaeadcf8fbbf97d76bd42aa4df0d6;hp=beabdefa6254a521da762d3a7c44274b29553edd;hpb=2031d0f586839bc68f35bcf8580b18947f8491d4;p=linux-2.6

diff --git a/mm/memory.c b/mm/memory.c
index beabdefa62..4e1c673784 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);
 
@@ -936,10 +938,9 @@ 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 +948,7 @@ 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 +967,6 @@ 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) {