VM: make zap_page_range() callers that act on a single VMA use separate helper

... and not rely on ->vm_next being there for them...

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

1 files changed, 74 insertions, 39 deletions

diff --git a/mm/memory.c b/mm/memory.c
index 016c67587ef4..8ab09188360a 100644
--- a/mm/memory.c
+++ b/mm/memory.c
@@ -1307,6 +1307,47 @@ static void unmap_page_range(struct mmu_gather *tlb,
         mem_cgroup_uncharge_end();
 }
 
+
+static void unmap_single_vma(struct mmu_gather *tlb,
+                struct vm_area_struct *vma, unsigned long start_addr,
+                unsigned long end_addr, unsigned long *nr_accounted,
+                struct zap_details *details)
+{
+        unsigned long start = max(vma->vm_start, start_addr);
+        unsigned long end;
+
+        if (start >= vma->vm_end)
+                return;
+        end = min(vma->vm_end, end_addr);
+        if (end <= vma->vm_start)
+                return;
+
+        if (vma->vm_flags & VM_ACCOUNT)
+                *nr_accounted += (end - start) >> PAGE_SHIFT;
+
+        if (unlikely(is_pfn_mapping(vma)))
+                untrack_pfn_vma(vma, 0, 0);
+
+        if (start != end) {
+                if (unlikely(is_vm_hugetlb_page(vma))) {
+                        /*
+                         * It is undesirable to test vma->vm_file as it
+                         * should be non-null for valid hugetlb area.
+                         * However, vm_file will be NULL in the error
+                         * cleanup path of do_mmap_pgoff. When
+                         * hugetlbfs ->mmap method fails,
+                         * do_mmap_pgoff() nullifies vma->vm_file
+                         * before calling this function to clean up.
+                         * Since no pte has actually been setup, it is
+                         * safe to do nothing in this case.
+                         */
+                        if (vma->vm_file)
+                                unmap_hugepage_range(vma, start, end, NULL);
+                } else
+                        unmap_page_range(tlb, vma, start, end, details);
+        }
+}
+
 /**
  * unmap_vmas - unmap a range of memory covered by a list of vma's
  * @tlb: address of the caller's struct mmu_gather
@@ -1332,46 +1373,12 @@ void unmap_vmas(struct mmu_gather *tlb,
                 unsigned long end_addr, unsigned long *nr_accounted,
                 struct zap_details *details)
 {
-        unsigned long start = start_addr;
         struct mm_struct *mm = vma->vm_mm;
 
         mmu_notifier_invalidate_range_start(mm, start_addr, end_addr);
-        for ( ; vma && vma->vm_start < end_addr; vma = vma->vm_next) {
-                unsigned long end;
-
-                start = max(vma->vm_start, start_addr);
-                if (start >= vma->vm_end)
-                        continue;
-                end = min(vma->vm_end, end_addr);
-                if (end <= vma->vm_start)
-                        continue;
-
-                if (vma->vm_flags & VM_ACCOUNT)
-                        *nr_accounted += (end - start) >> PAGE_SHIFT;
-
-                if (unlikely(is_pfn_mapping(vma)))
-                        untrack_pfn_vma(vma, 0, 0);
-
-                if (start != end) {
-                        if (unlikely(is_vm_hugetlb_page(vma))) {
-                                /*
-                                 * It is undesirable to test vma->vm_file as it
-                                 * should be non-null for valid hugetlb area.
-                                 * However, vm_file will be NULL in the error
-                                 * cleanup path of do_mmap_pgoff. When
-                                 * hugetlbfs ->mmap method fails,
-                                 * do_mmap_pgoff() nullifies vma->vm_file
-                                 * before calling this function to clean up.
-                                 * Since no pte has actually been setup, it is
-                                 * safe to do nothing in this case.
-                                 */
-                                if (vma->vm_file)
-                                        unmap_hugepage_range(vma, start, end, NULL);
-                        } else
-                                unmap_page_range(tlb, vma, start, end, details);
-                }
-        }
-
+        for ( ; vma && vma->vm_start < end_addr; vma = vma->vm_next)
+                unmap_single_vma(tlb, vma, start_addr, end_addr, nr_accounted,
+                                 details);
         mmu_notifier_invalidate_range_end(mm, start_addr, end_addr);
 }
 
@@ -1381,6 +1388,8 @@ void unmap_vmas(struct mmu_gather *tlb,
  * @address: starting address of pages to zap
  * @size: number of bytes to zap
  * @details: details of nonlinear truncation or shared cache invalidation
+ *
+ * Caller must protect the VMA list
  */
 void zap_page_range(struct vm_area_struct *vma, unsigned long address,
                 unsigned long size, struct zap_details *details)
@@ -1398,6 +1407,32 @@ void zap_page_range(struct vm_area_struct *vma, unsigned long address,
 }
 
 /**
+ * zap_page_range_single - remove user pages in a given range
+ * @vma: vm_area_struct holding the applicable pages
+ * @address: starting address of pages to zap
+ * @size: number of bytes to zap
+ * @details: details of nonlinear truncation or shared cache invalidation
+ *
+ * The range must fit into one VMA.
+ */
+static void zap_page_range_single(struct vm_area_struct *vma, unsigned long address,
+                unsigned long size, struct zap_details *details)
+{
+        struct mm_struct *mm = vma->vm_mm;
+        struct mmu_gather tlb;
+        unsigned long end = address + size;
+        unsigned long nr_accounted = 0;
+
+        lru_add_drain();
+        tlb_gather_mmu(&tlb, mm, 0);
+        update_hiwater_rss(mm);
+        mmu_notifier_invalidate_range_start(mm, address, end);
+        unmap_single_vma(&tlb, vma, address, end, &nr_accounted, details);
+        mmu_notifier_invalidate_range_end(mm, address, end);
+        tlb_finish_mmu(&tlb, address, end);
+}
+
+/**
  * zap_vma_ptes - remove ptes mapping the vma
  * @vma: vm_area_struct holding ptes to be zapped
  * @address: starting address of pages to zap
@@ -1415,7 +1450,7 @@ int zap_vma_ptes(struct vm_area_struct *vma, unsigned long address,
         if (address < vma->vm_start || address + size > vma->vm_end ||
                         !(vma->vm_flags & VM_PFNMAP))
                 return -1;
-        zap_page_range(vma, address, size, NULL);
+        zap_page_range_single(vma, address, size, NULL);
         return 0;
 }
 EXPORT_SYMBOL_GPL(zap_vma_ptes);
@@ -2762,7 +2797,7 @@ static void unmap_mapping_range_vma(struct vm_area_struct *vma,
                 unsigned long start_addr, unsigned long end_addr,
                 struct zap_details *details)
 {
-        zap_page_range(vma, start_addr, end_addr - start_addr, details);
+        zap_page_range_single(vma, start_addr, end_addr - start_addr, details);
 }
 
 static inline void unmap_mapping_range_tree(struct prio_tree_root *root,