mm: remove nopfn

There are no users of nopfn in the tree. Remove it.

[hugh@veritas.com: fix build error]
Signed-off-by: Nick Piggin <npiggin@suse.de>
Signed-off-by: Hugh Dickins <hugh@veritas.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

diff --git a/include/linux/mm.h b/include/linux/mm.h
index 2128ef7..eb815cf 100644 (file)
--- a/include/linux/mm.h
+++ b/include/linux/mm.h
@@ -166,8 +166,6 @@ struct vm_operations_struct {
        void (*open)(struct vm_area_struct * area);
        void (*close)(struct vm_area_struct * area);
        int (*fault)(struct vm_area_struct *vma, struct vm_fault *vmf);
-       unsigned long (*nopfn)(struct vm_area_struct *area,
-                       unsigned long address);
 
        /* notification that a previously read-only page is about to become
         * writable, if an error is returned it will cause a SIGBUS */
@@ -675,13 +673,6 @@ static inline int page_mapped(struct page *page)
 }
 
 /*
- * Error return values for the *_nopfn functions
- */
-#define NOPFN_SIGBUS   ((unsigned long) -1)
-#define NOPFN_OOM      ((unsigned long) -2)
-#define NOPFN_REFAULT  ((unsigned long) -3)
-
-/*
  * Different kinds of faults, as returned by handle_mm_fault().
  * Used to decide whether a process gets delivered SIGBUS or
  * just gets major/minor fault counters bumped up.

diff --git a/mm/memory.c b/mm/memory.c
index 2302d22..46dbed4 100644 (file)
--- a/mm/memory.c
+++ b/mm/memory.c
@@ -1058,11 +1058,9 @@ static inline int use_zero_page(struct vm_area_struct *vma)
        if (vma->vm_flags & (VM_LOCKED | VM_SHARED))
                return 0;
        /*
-        * And if we have a fault or a nopfn routine, it's not an
-        * anonymous region.
+        * And if we have a fault routine, it's not an anonymous region.
         */
-       return !vma->vm_ops ||
-               (!vma->vm_ops->fault && !vma->vm_ops->nopfn);
+       return !vma->vm_ops || !vma->vm_ops->fault;
 }
 
 int get_user_pages(struct task_struct *tsk, struct mm_struct *mm,
@@ -1338,6 +1336,11 @@ out:
  *
  * This function should only be called from a vm_ops->fault handler, and
  * in that case the handler should return NULL.
+ *
+ * vma cannot be a COW mapping.
+ *
+ * As this is called only for pages that do not currently exist, we
+ * do not need to flush old virtual caches or the TLB.
  */
 int vm_insert_pfn(struct vm_area_struct *vma, unsigned long addr,
                        unsigned long pfn)
@@ -2501,59 +2504,6 @@ static int do_linear_fault(struct mm_struct *mm, struct vm_area_struct *vma,
        return __do_fault(mm, vma, address, pmd, pgoff, flags, orig_pte);
 }
 
-
-/*
- * do_no_pfn() tries to create a new page mapping for a page without
- * a struct_page backing it
- *
- * As this is called only for pages that do not currently exist, we
- * do not need to flush old virtual caches or the TLB.
- *
- * We enter with non-exclusive mmap_sem (to exclude vma changes,
- * but allow concurrent faults), and pte mapped but not yet locked.
- * We return with mmap_sem still held, but pte unmapped and unlocked.
- *
- * It is expected that the ->nopfn handler always returns the same pfn
- * for a given virtual mapping.
- *
- * Mark this `noinline' to prevent it from bloating the main pagefault code.
- */
-static noinline int do_no_pfn(struct mm_struct *mm, struct vm_area_struct *vma,
-                    unsigned long address, pte_t *page_table, pmd_t *pmd,
-                    int write_access)
-{
-       spinlock_t *ptl;
-       pte_t entry;
-       unsigned long pfn;
-
-       pte_unmap(page_table);
-       BUG_ON(!(vma->vm_flags & (VM_PFNMAP|VM_MIXEDMAP)));
-       BUG_ON((vma->vm_flags & VM_PFNMAP) && is_cow_mapping(vma->vm_flags));
-
-       pfn = vma->vm_ops->nopfn(vma, address & PAGE_MASK);
-
-       BUG_ON((vma->vm_flags & VM_MIXEDMAP) && pfn_valid(pfn));
-
-       if (unlikely(pfn == NOPFN_OOM))
-               return VM_FAULT_OOM;
-       else if (unlikely(pfn == NOPFN_SIGBUS))
-               return VM_FAULT_SIGBUS;
-       else if (unlikely(pfn == NOPFN_REFAULT))
-               return 0;
-
-       page_table = pte_offset_map_lock(mm, pmd, address, &ptl);
-
-       /* Only go through if we didn't race with anybody else... */
-       if (pte_none(*page_table)) {
-               entry = pfn_pte(pfn, vma->vm_page_prot);
-               if (write_access)
-                       entry = maybe_mkwrite(pte_mkdirty(entry), vma);
-               set_pte_at(mm, address, page_table, entry);
-       }
-       pte_unmap_unlock(page_table, ptl);
-       return 0;
-}
-
 /*
  * Fault of a previously existing named mapping. Repopulate the pte
  * from the encoded file_pte if possible. This enables swappable
@@ -2614,9 +2564,6 @@ static inline int handle_pte_fault(struct mm_struct *mm,
                                if (likely(vma->vm_ops->fault))
                                        return do_linear_fault(mm, vma, address,
                                                pte, pmd, write_access, entry);
-                               if (unlikely(vma->vm_ops->nopfn))
-                                       return do_no_pfn(mm, vma, address, pte,
-                                                        pmd, write_access);
                        }
                        return do_anonymous_page(mm, vma, address,
                                                 pte, pmd, write_access);