mm: protect set_page_dirty() from ongoing truncation

[pandora-kernel.git] / mm / memory.c

diff --git a/mm/memory.c b/mm/memory.c
index 483e665..759f915 100644 (file)
--- a/mm/memory.c
+++ b/mm/memory.c
@@ -870,20 +870,20 @@ copy_one_pte(struct mm_struct *dst_mm, struct mm_struct *src_mm,
                if (!pte_file(pte)) {
                        swp_entry_t entry = pte_to_swp_entry(pte);
 
-                       if (swap_duplicate(entry) < 0)
-                               return entry.val;
-
-                       /* make sure dst_mm is on swapoff's mmlist. */
-                       if (unlikely(list_empty(&dst_mm->mmlist))) {
-                               spin_lock(&mmlist_lock);
-                               if (list_empty(&dst_mm->mmlist))
-                                       list_add(&dst_mm->mmlist,
-                                                &src_mm->mmlist);
-                               spin_unlock(&mmlist_lock);
-                       }
-                       if (likely(!non_swap_entry(entry)))
+                       if (likely(!non_swap_entry(entry))) {
+                               if (swap_duplicate(entry) < 0)
+                                       return entry.val;
+
+                               /* make sure dst_mm is on swapoff's mmlist. */
+                               if (unlikely(list_empty(&dst_mm->mmlist))) {
+                                       spin_lock(&mmlist_lock);
+                                       if (list_empty(&dst_mm->mmlist))
+                                               list_add(&dst_mm->mmlist,
+                                                        &src_mm->mmlist);
+                                       spin_unlock(&mmlist_lock);
+                               }
                                rss[MM_SWAPENTS]++;
-                       else if (is_write_migration_entry(entry) &&
+                       } else if (is_write_migration_entry(entry) &&
                                        is_cow_mapping(vm_flags)) {
                                /*
                                 * COW mappings require pages in both parent
@@ -1178,8 +1178,10 @@ again:
                        if (unlikely(page_mapcount(page) < 0))
                                print_bad_pte(vma, addr, ptent, page);
                        force_flush = !__tlb_remove_page(tlb, page);
-                       if (force_flush)
+                       if (force_flush) {
+                               addr += PAGE_SIZE;
                                break;
+                       }
                        continue;
                }
                /*
@@ -2659,17 +2661,24 @@ reuse:
                if (!dirty_page)
                        return ret;
 
-               /*
-                * Yes, Virginia, this is actually required to prevent a race
-                * with clear_page_dirty_for_io() from clearing the page dirty
-                * bit after it clear all dirty ptes, but before a racing
-                * do_wp_page installs a dirty pte.
-                *
-                * __do_fault is protected similarly.
-                */
                if (!page_mkwrite) {
-                       wait_on_page_locked(dirty_page);
-                       set_page_dirty_balance(dirty_page, page_mkwrite);
+                       struct address_space *mapping;
+                       int dirtied;
+
+                       lock_page(dirty_page);
+                       dirtied = set_page_dirty(dirty_page);
+                       VM_BUG_ON(PageAnon(dirty_page));
+                       mapping = dirty_page->mapping;
+                       unlock_page(dirty_page);
+
+                       if (dirtied && mapping) {
+                               /*
+                                * Some device drivers do not set page.mapping
+                                * but still dirty their pages
+                                */
+                               balance_dirty_pages_ratelimited(mapping);
+                       }
+
                }
                put_page(dirty_page);
                if (page_mkwrite) {
@@ -3115,7 +3124,7 @@ static inline int check_stack_guard_page(struct vm_area_struct *vma, unsigned lo
                if (prev && prev->vm_end == address)
                        return prev->vm_flags & VM_GROWSDOWN ? 0 : -ENOMEM;
 
-               expand_downwards(vma, address - PAGE_SIZE);
+               return expand_downwards(vma, address - PAGE_SIZE);
        }
        if ((vma->vm_flags & VM_GROWSUP) && address + PAGE_SIZE == vma->vm_end) {
                struct vm_area_struct *next = vma->vm_next;
@@ -3124,7 +3133,7 @@ static inline int check_stack_guard_page(struct vm_area_struct *vma, unsigned lo
                if (next && next->vm_start == address + PAGE_SIZE)
                        return next->vm_flags & VM_GROWSUP ? 0 : -ENOMEM;
 
-               expand_upwards(vma, address + PAGE_SIZE);
+               return expand_upwards(vma, address + PAGE_SIZE);
        }
        return 0;
 }