vma_has_reserves() can be substituted by using return value of
vma_needs_reservation(). If chg returned by vma_needs_reservation()
is 0, it means that vma has reserves. Otherwise, it means that vma don't
have reserves and need a hugepage outside of reserve pool. This definition
is perfectly same as vma_has_reserves(), so remove vma_has_reserves().

Reviewed-by: Aneesh Kumar K.V <aneesh.ku...@linux.vnet.ibm.com>
Signed-off-by: Joonsoo Kim <iamjoonsoo....@lge.com>

diff --git a/mm/hugetlb.c b/mm/hugetlb.c
index f394454..9d456d4 100644
--- a/mm/hugetlb.c
+++ b/mm/hugetlb.c
@@ -469,39 +469,6 @@ void reset_vma_resv_huge_pages(struct vm_area_struct *vma)
                vma->vm_private_data = (void *)0;
 }
 
-/* Returns true if the VMA has associated reserve pages */
-static int vma_has_reserves(struct vm_area_struct *vma, long chg)
-{
-       if (vma->vm_flags & VM_NORESERVE) {
-               /*
-                * This address is already reserved by other process(chg == 0),
-                * so, we should decrement reserved count. Without decrementing,
-                * reserve count remains after releasing inode, because this
-                * allocated page will go into page cache and is regarded as
-                * coming from reserved pool in releasing step.  Currently, we
-                * don't have any other solution to deal with this situation
-                * properly, so add work-around here.
-                */
-               if (vma->vm_flags & VM_MAYSHARE && chg == 0)
-                       return 1;
-               else
-                       return 0;
-       }
-
-       /* Shared mappings always use reserves */
-       if (vma->vm_flags & VM_MAYSHARE)
-               return 1;
-
-       /*
-        * Only the process that called mmap() has reserves for
-        * private mappings.
-        */
-       if (is_vma_resv_set(vma, HPAGE_RESV_OWNER))
-               return 1;
-
-       return 0;
-}
-
 static void enqueue_huge_page(struct hstate *h, struct page *page)
 {
        int nid = page_to_nid(page);
@@ -555,10 +522,11 @@ static struct page *dequeue_huge_page_vma(struct hstate 
*h,
        /*
         * A child process with MAP_PRIVATE mappings created by their parent
         * have no page reserves. This check ensures that reservations are
-        * not "stolen". The child may still get SIGKILLed
+        * not "stolen". The child may still get SIGKILLed.
+        * chg represents whether current user has a reserved hugepages or not,
+        * so that we can use it to ensure that reservations are not "stolen".
         */
-       if (!vma_has_reserves(vma, chg) &&
-                       h->free_huge_pages - h->resv_huge_pages == 0)
+       if (chg && h->free_huge_pages - h->resv_huge_pages == 0)
                goto err;
 
        /* If reserves cannot be used, ensure enough pages are in the pool */
@@ -577,7 +545,11 @@ retry_cpuset:
                        if (page) {
                                if (avoid_reserve)
                                        break;
-                               if (!vma_has_reserves(vma, chg))
+                               /*
+                                * chg means whether current user allocates
+                                * a hugepage on the reserved pool or not
+                                */
+                               if (chg)
                                        break;
 
                                SetPagePrivate(page);
-- 
1.7.9.5

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