Allow opportunistic merging of VM_CAN_NONLINEAR areas

[GitHub/mt8127/android_kernel_alcatel_ttab.git] / mm / mmap.c

diff --git a/mm/mmap.c b/mm/mmap.c
index 8d95902e9a389ba84fea3e45c39ad3c5012cee9d..c581df14d0de405fc1a2e43b2b939ecb151c5e8a 100644 (file)
--- 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;
@@ -1134,16 +1137,11 @@ munmap_back:
        }
 
        /*
-        * 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.
+        * Can we just expand an old mapping?
         */
-       if (!file && !(vm_flags & VM_SHARED)) {
-               vma = vma_merge(mm, prev, addr, addr + len, vm_flags,
-                                       NULL, NULL, pgoff, NULL);
-               if (vma)
-                       goto out;
-       }
+       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
@@ -1206,17 +1204,8 @@ 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)