diff options
| -rw-r--r-- | mm/memory.c | 37 |
1 files changed, 25 insertions, 12 deletions
diff --git a/mm/memory.c b/mm/memory.c index ece04963158..107b619cfb1 100644 --- a/mm/memory.c +++ b/mm/memory.c @@ -1277,22 +1277,28 @@ static int do_wp_page(struct mm_struct *mm, struct vm_area_struct *vma, unsigned long address, pte_t *page_table, pmd_t *pmd, spinlock_t *ptl, pte_t orig_pte) { - struct page *old_page, *new_page; + struct page *old_page, *src_page, *new_page; unsigned long pfn = pte_pfn(orig_pte); pte_t entry; int ret = VM_FAULT_MINOR; - BUG_ON(vma->vm_flags & VM_UNPAGED); - if (unlikely(!pfn_valid(pfn))) { /* * Page table corrupted: show pte and kill process. + * Or it's an attempt to COW an out-of-map VM_UNPAGED + * entry, which copy_user_highpage does not support. */ print_bad_pte(vma, orig_pte, address); ret = VM_FAULT_OOM; goto unlock; } old_page = pfn_to_page(pfn); + src_page = old_page; + + if (unlikely(vma->vm_flags & VM_UNPAGED)) { + old_page = NULL; + goto gotten; + } if (PageAnon(old_page) && !TestSetPageLocked(old_page)) { int reuse = can_share_swap_page(old_page); @@ -1313,11 +1319,12 @@ static int do_wp_page(struct mm_struct *mm, struct vm_area_struct *vma, * Ok, we need to copy. Oh, well.. */ page_cache_get(old_page); +gotten: pte_unmap_unlock(page_table, ptl); if (unlikely(anon_vma_prepare(vma))) goto oom; - if (old_page == ZERO_PAGE(address)) { + if (src_page == ZERO_PAGE(address)) { new_page = alloc_zeroed_user_highpage(vma, address); if (!new_page) goto oom; @@ -1325,7 +1332,7 @@ static int do_wp_page(struct mm_struct *mm, struct vm_area_struct *vma, new_page = alloc_page_vma(GFP_HIGHUSER, vma, address); if (!new_page) goto oom; - copy_user_highpage(new_page, old_page, address); + copy_user_highpage(new_page, src_page, address); } /* @@ -1333,11 +1340,14 @@ static int do_wp_page(struct mm_struct *mm, struct vm_area_struct *vma, */ page_table = pte_offset_map_lock(mm, pmd, address, &ptl); if (likely(pte_same(*page_table, orig_pte))) { - page_remove_rmap(old_page); - if (!PageAnon(old_page)) { + if (old_page) { + page_remove_rmap(old_page); + if (!PageAnon(old_page)) { + dec_mm_counter(mm, file_rss); + inc_mm_counter(mm, anon_rss); + } + } else inc_mm_counter(mm, anon_rss); - dec_mm_counter(mm, file_rss); - } flush_cache_page(vma, address, pfn); entry = mk_pte(new_page, vma->vm_page_prot); entry = maybe_mkwrite(pte_mkdirty(entry), vma); @@ -1351,13 +1361,16 @@ static int do_wp_page(struct mm_struct *mm, struct vm_area_struct *vma, new_page = old_page; ret |= VM_FAULT_WRITE; } - page_cache_release(new_page); - page_cache_release(old_page); + if (new_page) + page_cache_release(new_page); + if (old_page) + page_cache_release(old_page); unlock: pte_unmap_unlock(page_table, ptl); return ret; oom: - page_cache_release(old_page); + if (old_page) + page_cache_release(old_page); return VM_FAULT_OOM; } |