1 files changed, 76 insertions, 32 deletions

diff --git a/mm/memory.c b/mm/memory.c
index 6a4ef0fd0711..4126dd16778c 100644
--- a/mm/memory.c
+++ b/mm/memory.c
@@ -1971,6 +1971,15 @@ static int do_wp_page(struct mm_struct *mm, struct vm_area_struct *vma,
                                 ret = tmp;
                                 goto unwritable_page;
                         }
+                        if (unlikely(!(tmp & VM_FAULT_LOCKED))) {
+                                lock_page(old_page);
+                                if (!old_page->mapping) {
+                                        ret = 0; /* retry the fault */
+                                        unlock_page(old_page);
+                                        goto unwritable_page;
+                                }
+                        } else
+                                VM_BUG_ON(!PageLocked(old_page));
 
                         /*
                          * Since we dropped the lock we need to revalidate
@@ -1980,9 +1989,11 @@ static int do_wp_page(struct mm_struct *mm, struct vm_area_struct *vma,
                          */
                         page_table = pte_offset_map_lock(mm, pmd, address,
                                                          &ptl);
-                        page_cache_release(old_page);
-                        if (!pte_same(*page_table, orig_pte))
+                        if (!pte_same(*page_table, orig_pte)) {
+                                unlock_page(old_page);
+                                page_cache_release(old_page);
                                 goto unlock;
+                        }
 
                         page_mkwrite = 1;
                 }
@@ -2094,9 +2105,6 @@ gotten:
 unlock:
         pte_unmap_unlock(page_table, ptl);
         if (dirty_page) {
-                if (vma->vm_file)
-                        file_update_time(vma->vm_file);
-
                 /*
                  * Yes, Virginia, this is actually required to prevent a race
                  * with clear_page_dirty_for_io() from clearing the page dirty
@@ -2105,16 +2113,41 @@ unlock:
                  *
                  * do_no_page is protected similarly.
                  */
-                wait_on_page_locked(dirty_page);
-                set_page_dirty_balance(dirty_page, page_mkwrite);
+                if (!page_mkwrite) {
+                        wait_on_page_locked(dirty_page);
+                        set_page_dirty_balance(dirty_page, page_mkwrite);
+                }
                 put_page(dirty_page);
+                if (page_mkwrite) {
+                        struct address_space *mapping = dirty_page->mapping;
+
+                        set_page_dirty(dirty_page);
+                        unlock_page(dirty_page);
+                        page_cache_release(dirty_page);
+                        if (mapping)    {
+                                /*
+                                 * Some device drivers do not set page.mapping
+                                 * but still dirty their pages
+                                 */
+                                balance_dirty_pages_ratelimited(mapping);
+                        }
+                }
+
+                /* file_update_time outside page_lock */
+                if (vma->vm_file)
+                        file_update_time(vma->vm_file);
         }
         return ret;
 oom_free_new:
         page_cache_release(new_page);
 oom:
-        if (old_page)
+        if (old_page) {
+                if (page_mkwrite) {
+                        unlock_page(old_page);
+                        page_cache_release(old_page);
+                }
                 page_cache_release(old_page);
+        }
         return VM_FAULT_OOM;
 
 unwritable_page:
@@ -2664,27 +2697,22 @@ static int __do_fault(struct mm_struct *mm, struct vm_area_struct *vma,
                                 int tmp;
 
                                 unlock_page(page);
-                                vmf.flags |= FAULT_FLAG_MKWRITE;
+                                vmf.flags = FAULT_FLAG_WRITE|FAULT_FLAG_MKWRITE;
                                 tmp = vma->vm_ops->page_mkwrite(vma, &vmf);
                                 if (unlikely(tmp &
                                           (VM_FAULT_ERROR | VM_FAULT_NOPAGE))) {
                                         ret = tmp;
-                                        anon = 1; /* no anon but release vmf.page */
-                                        goto out_unlocked;
-                                }
-                                lock_page(page);
-                                /*
-                                 * XXX: this is not quite right (racy vs
-                                 * invalidate) to unlock and relock the page
-                                 * like this, however a better fix requires
-                                 * reworking page_mkwrite locking API, which
-                                 * is better done later.
-                                 */
-                                if (!page->mapping) {
-                                        ret = 0;
-                                        anon = 1; /* no anon but release vmf.page */
-                                        goto out;
+                                        goto unwritable_page;
                                 }
+                                if (unlikely(!(tmp & VM_FAULT_LOCKED))) {
+                                        lock_page(page);
+                                        if (!page->mapping) {
+                                                ret = 0; /* retry the fault */
+                                                unlock_page(page);
+                                                goto unwritable_page;
+                                        }
+                                } else
+                                        VM_BUG_ON(!PageLocked(page));
                                 page_mkwrite = 1;
                         }
                 }
@@ -2736,19 +2764,35 @@ static int __do_fault(struct mm_struct *mm, struct vm_area_struct *vma,
         pte_unmap_unlock(page_table, ptl);
 
 out:
-        unlock_page(vmf.page);
-out_unlocked:
-        if (anon)
-                page_cache_release(vmf.page);
-        else if (dirty_page) {
-                if (vma->vm_file)
-                        file_update_time(vma->vm_file);
+        if (dirty_page) {
+                struct address_space *mapping = page->mapping;
 
-                set_page_dirty_balance(dirty_page, page_mkwrite);
+                if (set_page_dirty(dirty_page))
+                        page_mkwrite = 1;
+                unlock_page(dirty_page);
                 put_page(dirty_page);
+                if (page_mkwrite && mapping) {
+                        /*
+                         * Some device drivers do not set page.mapping but still
+                         * dirty their pages
+                         */
+                        balance_dirty_pages_ratelimited(mapping);
+                }
+
+                /* file_update_time outside page_lock */
+                if (vma->vm_file)
+                        file_update_time(vma->vm_file);
+        } else {
+                unlock_page(vmf.page);
+                if (anon)
+                        page_cache_release(vmf.page);
         }
 
         return ret;
+
+unwritable_page:
+        page_cache_release(page);
+        return ret;
 }
 
 static int do_linear_fault(struct mm_struct *mm, struct vm_area_struct *vma,