badpage: zap print_bad_pte on swap and file

Complete zap_pte_range()'s coverage of bad pagetable entries by calling
print_bad_pte() on a pte_file in a linear vma and on a bad swap entry.
That needs free_swap_and_cache() to tell it, which will also have shown
one of those "swap_free" errors (but with much less information).

Similar checks in fork's copy_one_pte()?  No, that would be more noisy
than helpful: we'll see them when parent and child exec or exit.

Where do_nonlinear_fault() calls print_bad_pte(): omit !VM_CAN_NONLINEAR
case, that could only be a bug in sys_remap_file_pages(), not a bad pte.
VM_FAULT_OOM rather than VM_FAULT_SIGBUS?  Well, okay, that is consistent
with what happens if do_swap_page() operates a bad swap entry; but don't
we have patches to be more careful about killing when VM_FAULT_OOM?

Signed-off-by: Hugh Dickins <hugh@veritas.com>
Cc: Nick Piggin <nickpiggin@yahoo.com.au>
Cc: Christoph Lameter <cl@linux-foundation.org>
Cc: Mel Gorman <mel@csn.ul.ie>
Cc: Rik van Riel <riel@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

diff --git a/include/linux/swap.h b/include/linux/swap.h
index cbf7fbe..91dee50 100644 (file)
--- a/include/linux/swap.h
+++ b/include/linux/swap.h
@@ -302,7 +302,7 @@ extern swp_entry_t get_swap_page_of_type(int);
 extern int swap_duplicate(swp_entry_t);
 extern int valid_swaphandles(swp_entry_t, unsigned long *);
 extern void swap_free(swp_entry_t);
-extern void free_swap_and_cache(swp_entry_t);
+extern int free_swap_and_cache(swp_entry_t);
 extern int swap_type_of(dev_t, sector_t, struct block_device **);
 extern unsigned int count_swap_pages(int, int);
 extern sector_t map_swap_page(struct swap_info_struct *, pgoff_t);
@@ -352,14 +352,8 @@ static inline void show_swap_cache_info(void)
 {
 }
 
-static inline void free_swap_and_cache(swp_entry_t swp)
-{
-}
-
-static inline int swap_duplicate(swp_entry_t swp)
-{
-       return 0;
-}
+#define free_swap_and_cache(swp)       is_migration_entry(swp)
+#define swap_duplicate(swp)            is_migration_entry(swp)
 
 static inline void swap_free(swp_entry_t swp)
 {

diff --git a/mm/memory.c b/mm/memory.c
index 890095f..b273cc1 100644 (file)
--- a/mm/memory.c
+++ b/mm/memory.c
@@ -810,8 +810,12 @@ static unsigned long zap_pte_range(struct mmu_gather *tlb,
                 */
                if (unlikely(details))
                        continue;
-               if (!pte_file(ptent))
-                       free_swap_and_cache(pte_to_swp_entry(ptent));
+               if (pte_file(ptent)) {
+                       if (unlikely(!(vma->vm_flags & VM_NONLINEAR)))
+                               print_bad_pte(vma, addr, ptent, NULL);
+               } else if
+                 (unlikely(!free_swap_and_cache(pte_to_swp_entry(ptent))))
+                       print_bad_pte(vma, addr, ptent, NULL);
                pte_clear_not_present_full(mm, addr, pte, tlb->fullmm);
        } while (pte++, addr += PAGE_SIZE, (addr != end && *zap_work > 0));
 
@@ -2707,8 +2711,7 @@ static int do_nonlinear_fault(struct mm_struct *mm, struct vm_area_struct *vma,
        if (!pte_unmap_same(mm, pmd, page_table, orig_pte))
                return 0;
 
-       if (unlikely(!(vma->vm_flags & VM_NONLINEAR) ||
-                       !(vma->vm_flags & VM_CAN_NONLINEAR))) {
+       if (unlikely(!(vma->vm_flags & VM_NONLINEAR))) {
                /*
                 * Page table corrupted: show pte and kill process.
                 */

diff --git a/mm/swapfile.c b/mm/swapfile.c
index d005236..f287458 100644 (file)
--- a/mm/swapfile.c
+++ b/mm/swapfile.c
@@ -571,13 +571,13 @@ int try_to_free_swap(struct page *page)
  * Free the swap entry like above, but also try to
  * free the page cache entry if it is the last user.
  */
-void free_swap_and_cache(swp_entry_t entry)
+int free_swap_and_cache(swp_entry_t entry)
 {
-       struct swap_info_struct * p;
+       struct swap_info_struct *p;
        struct page *page = NULL;
 
        if (is_migration_entry(entry))
-               return;
+               return 1;
 
        p = swap_info_get(entry);
        if (p) {
@@ -603,6 +603,7 @@ void free_swap_and_cache(swp_entry_t entry)
                unlock_page(page);
                page_cache_release(page);
        }
+       return p != NULL;
 }
 
 #ifdef CONFIG_HIBERNATION