mm: do_wp_page() simplification

[linux-2.6-microblaze.git] / mm / memory.c

diff --git a/mm/memory.c b/mm/memory.c
index 87ec87c..56ae945 100644 (file)
--- a/mm/memory.c
+++ b/mm/memory.c
@@ -1601,7 +1601,7 @@ int vm_insert_pages(struct vm_area_struct *vma, unsigned long addr,
        return insert_pages(vma, addr, pages, num, vma->vm_page_prot);
 #else
        unsigned long idx = 0, pgcount = *num;
-       int err;
+       int err = -EINVAL;
 
        for (; idx < pgcount; ++idx) {
                err = vm_insert_page(vma, addr + (PAGE_SIZE * idx), pages[idx]);
@@ -2924,50 +2924,25 @@ static vm_fault_t do_wp_page(struct vm_fault *vmf)
         * not dirty accountable.
         */
        if (PageAnon(vmf->page)) {
-               int total_map_swapcount;
-               if (PageKsm(vmf->page) && (PageSwapCache(vmf->page) ||
-                                          page_count(vmf->page) != 1))
+               struct page *page = vmf->page;
+
+               /* PageKsm() doesn't necessarily raise the page refcount */
+               if (PageKsm(page) || page_count(page) != 1)
+                       goto copy;
+               if (!trylock_page(page))
+                       goto copy;
+               if (PageKsm(page) || page_mapcount(page) != 1 || page_count(page) != 1) {
+                       unlock_page(page);
                        goto copy;
-               if (!trylock_page(vmf->page)) {
-                       get_page(vmf->page);
-                       pte_unmap_unlock(vmf->pte, vmf->ptl);
-                       lock_page(vmf->page);
-                       vmf->pte = pte_offset_map_lock(vma->vm_mm, vmf->pmd,
-                                       vmf->address, &vmf->ptl);
-                       if (!pte_same(*vmf->pte, vmf->orig_pte)) {
-                               update_mmu_tlb(vma, vmf->address, vmf->pte);
-                               unlock_page(vmf->page);
-                               pte_unmap_unlock(vmf->pte, vmf->ptl);
-                               put_page(vmf->page);
-                               return 0;
-                       }
-                       put_page(vmf->page);
-               }
-               if (PageKsm(vmf->page)) {
-                       bool reused = reuse_ksm_page(vmf->page, vmf->vma,
-                                                    vmf->address);
-                       unlock_page(vmf->page);
-                       if (!reused)
-                               goto copy;
-                       wp_page_reuse(vmf);
-                       return VM_FAULT_WRITE;
-               }
-               if (reuse_swap_page(vmf->page, &total_map_swapcount)) {
-                       if (total_map_swapcount == 1) {
-                               /*
-                                * The page is all ours. Move it to
-                                * our anon_vma so the rmap code will
-                                * not search our parent or siblings.
-                                * Protected against the rmap code by
-                                * the page lock.
-                                */
-                               page_move_anon_rmap(vmf->page, vma);
-                       }
-                       unlock_page(vmf->page);
-                       wp_page_reuse(vmf);
-                       return VM_FAULT_WRITE;
                }
-               unlock_page(vmf->page);
+               /*
+                * Ok, we've got the only map reference, and the only
+                * page count reference, and the page is locked,
+                * it's dark out, and we're wearing sunglasses. Hit it.
+                */
+               wp_page_reuse(vmf);
+               unlock_page(page);
+               return VM_FAULT_WRITE;
        } else if (unlikely((vma->vm_flags & (VM_WRITE|VM_SHARED)) ==
                                        (VM_WRITE|VM_SHARED))) {
                return wp_page_shared(vmf);