3 files changed, 6 insertions, 4 deletions

diff --git a/include/linux/mm.h b/include/linux/mm.h
index 196924b657bc..df322fb4df31 100644
--- a/include/linux/mm.h
+++ b/include/linux/mm.h
@@ -100,6 +100,7 @@ extern unsigned int kobjsize(const void *objp);
 #define VM_DONTEXPAND   0x00040000      /* Cannot expand with mremap() */
 #define VM_RESERVED     0x00080000      /* Count as reserved_vm like IO */
 #define VM_ACCOUNT      0x00100000      /* Is a VM accounted object */
+#define VM_NORESERVE    0x00200000      /* should the VM suppress accounting */
 #define VM_HUGETLB      0x00400000      /* Huge TLB Page VM */
 #define VM_NONLINEAR    0x00800000      /* Is non-linear (remap_file_pages) */
 #define VM_MAPPED_COPY  0x01000000      /* T if mapped copy of data (nommu mmap) */
diff --git a/mm/mmap.c b/mm/mmap.c
index 75e0d0673d78..57d3b6097deb 100644
--- a/mm/mmap.c
+++ b/mm/mmap.c
@@ -1110,6 +1110,9 @@ munmap_back:
         if (!may_expand_vm(mm, len >> PAGE_SHIFT))
                 return -ENOMEM;
 
+        if (flags & MAP_NORESERVE)
+                vm_flags |= VM_NORESERVE;
+
         if (accountable && (!(flags & MAP_NORESERVE) ||
                             sysctl_overcommit_memory == OVERCOMMIT_NEVER)) {
                 if (vm_flags & VM_SHARED) {
diff --git a/mm/mprotect.c b/mm/mprotect.c
index 360d9cc8b38c..abd645a3b0a0 100644
--- a/mm/mprotect.c
+++ b/mm/mprotect.c
@@ -153,12 +153,10 @@ mprotect_fixup(struct vm_area_struct *vma, struct vm_area_struct **pprev,
          * If we make a private mapping writable we increase our commit;
          * but (without finer accounting) cannot reduce our commit if we
          * make it unwritable again.
-         *
-         * FIXME? We haven't defined a VM_NORESERVE flag, so mprotecting
-         * a MAP_NORESERVE private mapping to writable will now reserve.
          */
         if (newflags & VM_WRITE) {
-                if (!(oldflags & (VM_ACCOUNT|VM_WRITE|VM_SHARED))) {
+                if (!(oldflags & (VM_ACCOUNT|VM_WRITE|
+                                                VM_SHARED|VM_NORESERVE))) {
                         charged = nrpages;
                         if (security_vm_enough_memory(charged))
                                 return -ENOMEM;