mm/mlock: Use vma iterator and instead of vma linked list

Handle overflow checking in count_mm_mlocked_page_nr() differently.

Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Signed-off-by: Liam R. Howlett <Liam.Howlett@Oracle.com>

diff --git a/mm/mlock.c b/mm/mlock.c
index 8f584eddd305380d3aae8fb810998e9530468f42..8d54f355080f0b1fa3e657d8868908bdd407bf1a 100644 (file)
--- a/mm/mlock.c
+++ b/mm/mlock.c
@@ -563,6 +563,7 @@ static int apply_vma_lock_flags(unsigned long start, size_t len,
        unsigned long nstart, end, tmp;
        struct vm_area_struct *vma, *prev;
        int error;
+       MA_STATE(mas, &current->mm->mm_mt, start, start);
 
        VM_BUG_ON(offset_in_page(start));
        VM_BUG_ON(len != PAGE_ALIGN(len));
@@ -571,13 +572,14 @@ static int apply_vma_lock_flags(unsigned long start, size_t len,
                return -EINVAL;
        if (end == start)
                return 0;
-       vma = find_vma(current->mm, start);
-       if (!vma || vma->vm_start > start)
+       vma = mas_walk(&mas);
+       if (!vma)
                return -ENOMEM;
 
-       prev = vma->vm_prev;
        if (start > vma->vm_start)
                prev = vma;
+       else
+               prev = mas_prev(&mas, 0);
 
        for (nstart = start ; ; ) {
                vm_flags_t newflags = vma->vm_flags & VM_LOCKED_CLEAR_MASK;
@@ -597,7 +599,7 @@ static int apply_vma_lock_flags(unsigned long start, size_t len,
                if (nstart >= end)
                        break;
 
-               vma = prev->vm_next;
+               vma = find_vma(prev->vm_mm, prev->vm_end);
                if (!vma || vma->vm_start != nstart) {
                        error = -ENOMEM;
                        break;
@@ -618,24 +620,23 @@ static unsigned long count_mm_mlocked_page_nr(struct mm_struct *mm,
 {
        struct vm_area_struct *vma;
        unsigned long count = 0;
+       unsigned long end;
+       VMA_ITERATOR(vmi, mm, start);
 
        if (mm == NULL)
                mm = current->mm;
 
-       vma = find_vma(mm, start);
-       if (vma == NULL)
-               return 0;
-
-       for (; vma ; vma = vma->vm_next) {
-               if (start >= vma->vm_end)
-                       continue;
-               if (start + len <=  vma->vm_start)
-                       break;
+       /* Don't overflow past ULONG_MAX */
+       if (unlikely(ULONG_MAX - len < start))
+               end = ULONG_MAX;
+       else
+               end = start + len;
+       for_each_vma_range(vmi, vma, end) {
                if (vma->vm_flags & VM_LOCKED) {
                        if (start > vma->vm_start)
                                count -= (start - vma->vm_start);
-                       if (start + len < vma->vm_end) {
-                               count += start + len - vma->vm_start;
+                       if (end < vma->vm_end) {
+                               count += end - vma->vm_start;
                                break;
                        }
                        count += vma->vm_end - vma->vm_start;
@@ -739,6 +740,7 @@ SYSCALL_DEFINE2(munlock, unsigned long, start, size_t, len)
  */
 static int apply_mlockall_flags(int flags)
 {
+       VMA_ITERATOR(vmi, current->mm, 0);
        struct vm_area_struct *vma, *prev = NULL;
        vm_flags_t to_add = 0;
 
@@ -759,7 +761,7 @@ static int apply_mlockall_flags(int flags)
                        to_add |= VM_LOCKONFAULT;
        }
 
-       for (vma = current->mm->mmap; vma ; vma = prev->vm_next) {
+       for_each_vma(vmi, vma) {
                vm_flags_t newflags;
 
                newflags = vma->vm_flags & VM_LOCKED_CLEAR_MASK;