1 files changed, 54 insertions, 55 deletions

diff --git a/mm/mmap.c b/mm/mmap.c
index 8d95902e9a38..00ced3ee49a8 100644
--- a/mm/mmap.c
+++ b/mm/mmap.c
@@ -658,6 +658,9 @@ again:			remove_next = 1 + (end > next->vm_end);
         validate_mm(mm);
 }
 
+/* Flags that can be inherited from an existing mapping when merging */
+#define VM_MERGEABLE_FLAGS (VM_CAN_NONLINEAR)
+
 /*
  * If the vma has a ->close operation then the driver probably needs to release
  * per-vma resources, so we don't attempt to merge those.
@@ -665,7 +668,7 @@ again:			remove_next = 1 + (end > next->vm_end);
 static inline int is_mergeable_vma(struct vm_area_struct *vma,
                         struct file *file, unsigned long vm_flags)
 {
-        if (vma->vm_flags != vm_flags)
+        if ((vma->vm_flags ^ vm_flags) & ~VM_MERGEABLE_FLAGS)
                 return 0;
         if (vma->vm_file != file)
                 return 0;
@@ -915,7 +918,6 @@ unsigned long do_mmap_pgoff(struct file *file, unsigned long addr,
         struct inode *inode;
         unsigned int vm_flags;
         int error;
-        int accountable = 1;
         unsigned long reqprot = prot;
 
         /*
@@ -1016,8 +1018,6 @@ unsigned long do_mmap_pgoff(struct file *file, unsigned long addr,
                                         return -EPERM;
                                 vm_flags &= ~VM_MAYEXEC;
                         }
-                        if (is_file_hugepages(file))
-                                accountable = 0;
 
                         if (!file->f_op || !file->f_op->mmap)
                                 return -ENODEV;
@@ -1050,8 +1050,7 @@ unsigned long do_mmap_pgoff(struct file *file, unsigned long addr,
         if (error)
                 return error;
 
-        return mmap_region(file, addr, len, flags, vm_flags, pgoff,
-                           accountable);
+        return mmap_region(file, addr, len, flags, vm_flags, pgoff);
 }
 EXPORT_SYMBOL(do_mmap_pgoff);
 
@@ -1087,10 +1086,25 @@ int vma_wants_writenotify(struct vm_area_struct *vma)
                 mapping_cap_account_dirty(vma->vm_file->f_mapping);
 }
 
+/*
+ * We account for memory if it's a private writeable mapping,
+ * not hugepages and VM_NORESERVE wasn't set.
+ */
+static inline int accountable_mapping(struct file *file, unsigned int vm_flags)
+{
+        /*
+         * hugetlb has its own accounting separate from the core VM
+         * VM_HUGETLB may not be set yet so we cannot check for that flag.
+         */
+        if (file && is_file_hugepages(file))
+                return 0;
+
+        return (vm_flags & (VM_NORESERVE | VM_SHARED | VM_WRITE)) == VM_WRITE;
+}
+
 unsigned long mmap_region(struct file *file, unsigned long addr,
                           unsigned long len, unsigned long flags,
-                          unsigned int vm_flags, unsigned long pgoff,
-                          int accountable)
+                          unsigned int vm_flags, unsigned long pgoff)
 {
         struct mm_struct *mm = current->mm;
         struct vm_area_struct *vma, *prev;
@@ -1114,38 +1128,38 @@ munmap_back:
         if (!may_expand_vm(mm, len >> PAGE_SHIFT))
                 return -ENOMEM;
 
-        if (flags & MAP_NORESERVE)
-                vm_flags |= VM_NORESERVE;
+        /*
+         * Set 'VM_NORESERVE' if we should not account for the
+         * memory use of this mapping.
+         */
+        if ((flags & MAP_NORESERVE)) {
+                /* We honor MAP_NORESERVE if allowed to overcommit */
+                if (sysctl_overcommit_memory != OVERCOMMIT_NEVER)
+                        vm_flags |= VM_NORESERVE;
 
-        if (accountable && (!(flags & MAP_NORESERVE) ||
-                            sysctl_overcommit_memory == OVERCOMMIT_NEVER)) {
-                if (vm_flags & VM_SHARED) {
-                        /* Check memory availability in shmem_file_setup? */
-                        vm_flags |= VM_ACCOUNT;
-                } else if (vm_flags & VM_WRITE) {
-                        /*
-                         * Private writable mapping: check memory availability
-                         */
-                        charged = len >> PAGE_SHIFT;
-                        if (security_vm_enough_memory(charged))
-                                return -ENOMEM;
-                        vm_flags |= VM_ACCOUNT;
-                }
+                /* hugetlb applies strict overcommit unless MAP_NORESERVE */
+                if (file && is_file_hugepages(file))
+                        vm_flags |= VM_NORESERVE;
         }
 
         /*
-         * Can we just expand an old private anonymous mapping?
-         * The VM_SHARED test is necessary because shmem_zero_setup
-         * will create the file object for a shared anonymous map below.
+         * Private writable mapping: check memory availability
          */
-        if (!file && !(vm_flags & VM_SHARED)) {
-                vma = vma_merge(mm, prev, addr, addr + len, vm_flags,
-                                        NULL, NULL, pgoff, NULL);
-                if (vma)
-                        goto out;
+        if (accountable_mapping(file, vm_flags)) {
+                charged = len >> PAGE_SHIFT;
+                if (security_vm_enough_memory(charged))
+                        return -ENOMEM;
+                vm_flags |= VM_ACCOUNT;
         }
 
         /*
+         * Can we just expand an old mapping?
+         */
+        vma = vma_merge(mm, prev, addr, addr + len, vm_flags, NULL, file, pgoff, NULL);
+        if (vma)
+                goto out;
+
+        /*
          * Determine the object being mapped and call the appropriate
          * specific mapper. the address has already been validated, but
          * not unmapped, but the maps are removed from the list.
@@ -1186,14 +1200,6 @@ munmap_back:
                         goto free_vma;
         }
 
-        /* We set VM_ACCOUNT in a shared mapping's vm_flags, to inform
-         * shmem_zero_setup (perhaps called through /dev/zero's ->mmap)
-         * that memory reservation must be checked; but that reservation
-         * belongs to shared memory object, not to vma: so now clear it.
-         */
-        if ((vm_flags & (VM_SHARED|VM_ACCOUNT)) == (VM_SHARED|VM_ACCOUNT))
-                vma->vm_flags &= ~VM_ACCOUNT;
-
         /* Can addr have changed??
          *
          * Answer: Yes, several device drivers can do it in their
@@ -1206,17 +1212,8 @@ munmap_back:
         if (vma_wants_writenotify(vma))
                 vma->vm_page_prot = vm_get_page_prot(vm_flags & ~VM_SHARED);
 
-        if (file && vma_merge(mm, prev, addr, vma->vm_end,
-                        vma->vm_flags, NULL, file, pgoff, vma_policy(vma))) {
-                mpol_put(vma_policy(vma));
-                kmem_cache_free(vm_area_cachep, vma);
-                fput(file);
-                if (vm_flags & VM_EXECUTABLE)
-                        removed_exe_file_vma(mm);
-        } else {
-                vma_link(mm, vma, prev, rb_link, rb_parent);
-                file = vma->vm_file;
-        }
+        vma_link(mm, vma, prev, rb_link, rb_parent);
+        file = vma->vm_file;
 
         /* Once vma denies write, undo our temporary denial count */
         if (correct_wcount)
@@ -2087,12 +2084,8 @@ void exit_mmap(struct mm_struct *mm)
         unsigned long end;
 
         /* mm's last user has gone, and its about to be pulled down */
-        arch_exit_mmap(mm);
         mmu_notifier_release(mm);
 
-        if (!mm->mmap)  /* Can happen if dup_mmap() received an OOM */
-                return;
-
         if (mm->locked_vm) {
                 vma = mm->mmap;
                 while (vma) {
@@ -2101,7 +2094,13 @@ void exit_mmap(struct mm_struct *mm)
                         vma = vma->vm_next;
                 }
         }
+
+        arch_exit_mmap(mm);
+
         vma = mm->mmap;
+        if (!vma)       /* Can happen if dup_mmap() received an OOM */
+                return;
+
         lru_add_drain();
         flush_cache_mm(mm);
         tlb = tlb_gather_mmu(mm, 1);