Merge branch 'master'

[linux-2.6] / mm / memory.c

diff --git a/mm/memory.c b/mm/memory.c
index 4b4fc3a7ea4858a1bba7e2aa60f1ace8fdbd4e0c..47c533eaa0721c558eddcc68dfa6c8de1f2844ef 100644 (file)
--- a/mm/memory.c
+++ b/mm/memory.c
@@ -349,6 +349,11 @@ void print_bad_pte(struct vm_area_struct *vma, pte_t pte, unsigned long vaddr)
        dump_stack();
 }
 
+static inline int is_cow_mapping(unsigned int flags)
+{
+       return (flags & (VM_SHARED | VM_MAYWRITE)) == VM_MAYWRITE;
+}
+
 /*
  * This function gets the "struct page" associated with a pte.
  *
@@ -377,6 +382,8 @@ struct page *vm_normal_page(struct vm_area_struct *vma, unsigned long addr, pte_
                unsigned long off = (addr - vma->vm_start) >> PAGE_SHIFT;
                if (pfn == vma->vm_pgoff + off)
                        return NULL;
+               if (!is_cow_mapping(vma->vm_flags))
+                       return NULL;
        }
 
        /*
@@ -437,7 +444,7 @@ copy_one_pte(struct mm_struct *dst_mm, struct mm_struct *src_mm,
         * If it's a COW mapping, write protect it both
         * in the parent and the child
         */
-       if ((vm_flags & (VM_SHARED | VM_MAYWRITE)) == VM_MAYWRITE) {
+       if (is_cow_mapping(vm_flags)) {
                ptep_set_wrprotect(src_mm, addr, src_pte);
                pte = *src_pte;
        }
@@ -1223,51 +1230,7 @@ int vm_insert_page(struct vm_area_struct *vma, unsigned long addr, struct page *
                return -EINVAL;
        return insert_page(vma->vm_mm, addr, page, vma->vm_page_prot);
 }
-EXPORT_SYMBOL_GPL(vm_insert_page);
-
-/*
- * Somebody does a pfn remapping that doesn't actually work as a vma.
- *
- * Do it as individual pages instead, and warn about it. It's bad form,
- * and very inefficient.
- */
-static int incomplete_pfn_remap(struct vm_area_struct *vma,
-               unsigned long start, unsigned long end,
-               unsigned long pfn, pgprot_t prot)
-{
-       static int warn = 10;
-       struct page *page;
-       int retval;
-
-       if (!(vma->vm_flags & VM_INCOMPLETE)) {
-               if (warn) {
-                       warn--;
-                       printk("%s does an incomplete pfn remapping", current->comm);
-                       dump_stack();
-               }
-       }
-       vma->vm_flags |= VM_INCOMPLETE | VM_IO | VM_RESERVED;
-
-       if (start < vma->vm_start || end > vma->vm_end)
-               return -EINVAL;
-
-       if (!pfn_valid(pfn))
-               return -EINVAL;
-
-       page = pfn_to_page(pfn);
-       if (!PageReserved(page))
-               return -EINVAL;
-
-       retval = 0;
-       while (start < end) {
-               retval = insert_page(vma->vm_mm, start, page, prot);
-               if (retval < 0)
-                       break;
-               start += PAGE_SIZE;
-               page++;
-       }
-       return retval;
-}
+EXPORT_SYMBOL(vm_insert_page);
 
 /*
  * maps a range of physical memory into the requested pages. the old
@@ -1343,9 +1306,6 @@ int remap_pfn_range(struct vm_area_struct *vma, unsigned long addr,
        struct mm_struct *mm = vma->vm_mm;
        int err;
 
-       if (addr != vma->vm_start || end != vma->vm_end)
-               return incomplete_pfn_remap(vma, addr, end, pfn, prot);
-
        /*
         * Physically remapped pages are special. Tell the
         * rest of the world about it:
@@ -1359,9 +1319,18 @@ int remap_pfn_range(struct vm_area_struct *vma, unsigned long addr,
         *   VM_PFNMAP tells the core MM that the base pages are just
         *      raw PFN mappings, and do not have a "struct page" associated
         *      with them.
+        *
+        * There's a horrible special case to handle copy-on-write
+        * behaviour that some programs depend on. We mark the "original"
+        * un-COW'ed pages by matching them up with "vma->vm_pgoff".
         */
+       if (is_cow_mapping(vma->vm_flags)) {
+               if (addr != vma->vm_start || end != vma->vm_end)
+                       return -EINVAL;
+               vma->vm_pgoff = pfn;
+       }
+
        vma->vm_flags |= VM_IO | VM_RESERVED | VM_PFNMAP;
-       vma->vm_pgoff = pfn;
 
        BUG_ON(addr >= end);
        pfn -= addr >> PAGE_SHIFT;