mm: introduce debug_kmap_atomic

[safe/jmp/linux-2.6] / mm / memory.c

diff --git a/mm/memory.c b/mm/memory.c
index 0017111..cf6873e 100644 (file)
--- a/mm/memory.c
+++ b/mm/memory.c
@@ -1151,6 +1151,11 @@ struct page *follow_page(struct vm_area_struct *vma, unsigned long address,
                if ((flags & FOLL_WRITE) &&
                    !pte_dirty(pte) && !PageDirty(page))
                        set_page_dirty(page);
+               /*
+                * pte_mkyoung() would be more correct here, but atomic care
+                * is needed to avoid losing the dirty bit: it is easier to use
+                * mark_page_accessed().
+                */
                mark_page_accessed(page);
        }
 unlock:
@@ -1940,6 +1945,15 @@ static int do_wp_page(struct mm_struct *mm, struct vm_area_struct *vma,
                 * get_user_pages(.write=1, .force=1).
                 */
                if (vma->vm_ops && vma->vm_ops->page_mkwrite) {
+                       struct vm_fault vmf;
+                       int tmp;
+
+                       vmf.virtual_address = (void __user *)(address &
+                                                               PAGE_MASK);
+                       vmf.pgoff = old_page->index;
+                       vmf.flags = FAULT_FLAG_WRITE|FAULT_FLAG_MKWRITE;
+                       vmf.page = old_page;
+
                        /*
                         * Notify the address space that the page is about to
                         * become writable so that it can prohibit this or wait
@@ -1951,8 +1965,12 @@ static int do_wp_page(struct mm_struct *mm, struct vm_area_struct *vma,
                        page_cache_get(old_page);
                        pte_unmap_unlock(page_table, ptl);
 
-                       if (vma->vm_ops->page_mkwrite(vma, old_page) < 0)
+                       tmp = vma->vm_ops->page_mkwrite(vma, &vmf);
+                       if (unlikely(tmp &
+                                       (VM_FAULT_ERROR | VM_FAULT_NOPAGE))) {
+                               ret = tmp;
                                goto unwritable_page;
+                       }
 
                        /*
                         * Since we dropped the lock we need to revalidate
@@ -2101,7 +2119,7 @@ oom:
 
 unwritable_page:
        page_cache_release(old_page);
-       return VM_FAULT_SIGBUS;
+       return ret;
 }
 
 /*
@@ -2643,9 +2661,14 @@ static int __do_fault(struct mm_struct *mm, struct vm_area_struct *vma,
                         * to become writable
                         */
                        if (vma->vm_ops->page_mkwrite) {
+                               int tmp;
+
                                unlock_page(page);
-                               if (vma->vm_ops->page_mkwrite(vma, page) < 0) {
-                                       ret = VM_FAULT_SIGBUS;
+                               vmf.flags |= 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;
                                }