mm/mmap.c:insert_vm_struct(): check for failure before setting values

There's no point in initializing vma->vm_pgoff if the insertion attempt
will be failing anyway.  Run the checks before performing the
initialization.

Signed-off-by: Chen Gang <gang.chen.5i5j@gmail.com>
Cc: Michal Hocko <mhocko@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

diff --git a/mm/mmap.c b/mm/mmap.c
index 7a3b12399f063688d352779185de22b682380e3b..b6be3249f0a923cf1735405726f17cc4de8085a7 100644 (file)
--- a/mm/mmap.c
+++ b/mm/mmap.c
@@ -2871,6 +2871,13 @@ int insert_vm_struct(struct mm_struct *mm, struct vm_area_struct *vma)
        struct vm_area_struct *prev;
        struct rb_node **rb_link, *rb_parent;
 
+       if (find_vma_links(mm, vma->vm_start, vma->vm_end,
+                          &prev, &rb_link, &rb_parent))
+               return -ENOMEM;
+       if ((vma->vm_flags & VM_ACCOUNT) &&
+            security_vm_enough_memory_mm(mm, vma_pages(vma)))
+               return -ENOMEM;
+
        /*
         * The vm_pgoff of a purely anonymous vma should be irrelevant
         * until its first write fault, when page's anon_vma and index
@@ -2887,12 +2894,6 @@ int insert_vm_struct(struct mm_struct *mm, struct vm_area_struct *vma)
                BUG_ON(vma->anon_vma);
                vma->vm_pgoff = vma->vm_start >> PAGE_SHIFT;
        }
-       if (find_vma_links(mm, vma->vm_start, vma->vm_end,
-                          &prev, &rb_link, &rb_parent))
-               return -ENOMEM;
-       if ((vma->vm_flags & VM_ACCOUNT) &&
-            security_vm_enough_memory_mm(mm, vma_pages(vma)))
-               return -ENOMEM;
 
        vma_link(mm, vma, prev, rb_link, rb_parent);
        return 0;