vma_need_reservation() can be substituted by vma_has_reserves()
with minor change. These function do almost same thing,
so unifying them is better to maintain.

Signed-off-by: Joonsoo Kim <iamjoonsoo....@lge.com>

diff --git a/mm/hugetlb.c b/mm/hugetlb.c
index bf2ee11..ff46a2c 100644
--- a/mm/hugetlb.c
+++ b/mm/hugetlb.c
@@ -451,8 +451,18 @@ 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)
+/*
+ * Determine if the huge page at addr within the vma has an associated
+ * reservation.  Where it does not we will need to logically increase
+ * reservation and actually increase subpool usage before an allocation
+ * can occur.  Where any new reservation would be required the
+ * reservation change is prepared, but not committed.  Once the page
+ * has been allocated from the subpool and instantiated the change should
+ * be committed via vma_commit_reservation.  No action is required on
+ * failure.
+ */
+static int vma_has_reserves(struct hstate *h,
+                       struct vm_area_struct *vma, unsigned long addr)
 {
        if (vma->vm_flags & VM_NORESERVE) {
                /*
@@ -464,10 +474,22 @@ static int vma_has_reserves(struct vm_area_struct *vma, 
long chg)
                 * 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;
+               if (vma->vm_flags & VM_MAYSHARE) {
+                       struct address_space *mapping = vma->vm_file->f_mapping;
+                       struct inode *inode = mapping->host;
+                       pgoff_t idx = vma_hugecache_offset(h, vma, addr);
+                       struct resv_map *resv = inode->i_mapping->private_data;
+                       long chg;
+
+                       chg = region_chg(resv, idx, idx + 1);
+                       if (chg < 0)
+                               return -ENOMEM;
+
+                       if (chg == 0)
+                               return 1;
+               }
+
+               return 0;
        }
 
        /* Shared mappings always use reserves */
@@ -478,8 +500,16 @@ static int vma_has_reserves(struct vm_area_struct *vma, 
long chg)
         * Only the process that called mmap() has reserves for
         * private mappings.
         */
-       if (is_vma_resv_set(vma, HPAGE_RESV_OWNER))
+       if (is_vma_resv_set(vma, HPAGE_RESV_OWNER)) {
+               pgoff_t idx = vma_hugecache_offset(h, vma, addr);
+               struct resv_map *resv = vma_resv_map(vma);
+
+               /* Just for allocating region structure */
+               if (region_chg(resv, idx, idx + 1) < 0)
+                       return -ENOMEM;
+
                return 1;
+       }
 
        return 0;
 }
@@ -542,8 +572,7 @@ static struct page *dequeue_huge_page_node(struct hstate 
*h, int nid)
 
 static struct page *dequeue_huge_page_vma(struct hstate *h,
                                struct vm_area_struct *vma,
-                               unsigned long address, int avoid_reserve,
-                               long chg)
+                               unsigned long address, int avoid_reserve)
 {
        struct page *page = NULL;
        struct mempolicy *mpol;
@@ -558,7 +587,7 @@ static struct page *dequeue_huge_page_vma(struct hstate *h,
         * have no page reserves. This check ensures that reservations are
         * not "stolen". The child may still get SIGKILLed
         */
-       if (!vma_has_reserves(vma, chg) &&
+       if (!vma_has_reserves(h, vma, address) &&
                        h->free_huge_pages - h->resv_huge_pages == 0)
                return NULL;
 
@@ -578,7 +607,7 @@ retry_cpuset:
                        if (page) {
                                if (avoid_reserve)
                                        break;
-                               if (!vma_has_reserves(vma, chg))
+                               if (!vma_has_reserves(h, vma, address))
                                        break;
 
                                h->resv_huge_pages--;
@@ -1077,42 +1106,6 @@ static void return_unused_surplus_pages(struct hstate *h,
        }
 }
 
-/*
- * Determine if the huge page at addr within the vma has an associated
- * reservation.  Where it does not we will need to logically increase
- * reservation and actually increase subpool usage before an allocation
- * can occur.  Where any new reservation would be required the
- * reservation change is prepared, but not committed.  Once the page
- * has been allocated from the subpool and instantiated the change should
- * be committed via vma_commit_reservation.  No action is required on
- * failure.
- */
-static long vma_needs_reservation(struct hstate *h,
-                       struct vm_area_struct *vma, unsigned long addr)
-{
-       struct address_space *mapping = vma->vm_file->f_mapping;
-       struct inode *inode = mapping->host;
-
-       if (vma->vm_flags & VM_MAYSHARE) {
-               pgoff_t idx = vma_hugecache_offset(h, vma, addr);
-               struct resv_map *resv = inode->i_mapping->private_data;
-
-               return region_chg(resv, idx, idx + 1);
-
-       } else if (!is_vma_resv_set(vma, HPAGE_RESV_OWNER)) {
-               return 1;
-
-       } else  {
-               long err;
-               pgoff_t idx = vma_hugecache_offset(h, vma, addr);
-               struct resv_map *resv = vma_resv_map(vma);
-
-               err = region_chg(resv, idx, idx + 1);
-               if (err < 0)
-                       return err;
-               return 0;
-       }
-}
 static void vma_commit_reservation(struct hstate *h,
                        struct vm_area_struct *vma, unsigned long addr)
 {
@@ -1140,8 +1133,7 @@ static struct page *alloc_huge_page(struct vm_area_struct 
*vma,
        struct hugepage_subpool *spool = subpool_vma(vma);
        struct hstate *h = hstate_vma(vma);
        struct page *page;
-       long chg;
-       int ret, idx;
+       int ret, idx, has_reserve;
        struct hugetlb_cgroup *h_cg;
 
        idx = hstate_index(h);
@@ -1153,20 +1145,21 @@ static struct page *alloc_huge_page(struct 
vm_area_struct *vma,
         * need pages and subpool limit allocated allocated if no reserve
         * mapping overlaps.
         */
-       chg = vma_needs_reservation(h, vma, addr);
-       if (chg < 0)
+       has_reserve = vma_has_reserves(h, vma, addr);
+       if (has_reserve < 0)
                return ERR_PTR(-ENOMEM);
-       if (chg)
-               if (hugepage_subpool_get_pages(spool, chg))
+
+       if (!has_reserve && (hugepage_subpool_get_pages(spool, 1) < 0))
                        return ERR_PTR(-ENOSPC);
 
        ret = hugetlb_cgroup_charge_cgroup(idx, pages_per_huge_page(h), &h_cg);
        if (ret) {
-               hugepage_subpool_put_pages(spool, chg);
+               if (!has_reserve)
+                       hugepage_subpool_put_pages(spool, 1);
                return ERR_PTR(-ENOSPC);
        }
        spin_lock(&hugetlb_lock);
-       page = dequeue_huge_page_vma(h, vma, addr, avoid_reserve, chg);
+       page = dequeue_huge_page_vma(h, vma, addr, avoid_reserve);
        if (!page) {
                spin_unlock(&hugetlb_lock);
                page = alloc_buddy_huge_page(h, NUMA_NO_NODE);
@@ -1174,7 +1167,8 @@ static struct page *alloc_huge_page(struct vm_area_struct 
*vma,
                        hugetlb_cgroup_uncharge_cgroup(idx,
                                                       pages_per_huge_page(h),
                                                       h_cg);
-                       hugepage_subpool_put_pages(spool, chg);
+                       if (!has_reserve)
+                               hugepage_subpool_put_pages(spool, 1);
                        return ERR_PTR(-ENOSPC);
                }
                spin_lock(&hugetlb_lock);
@@ -2769,7 +2763,7 @@ retry:
         * the spinlock.
         */
        if ((flags & FAULT_FLAG_WRITE) && !(vma->vm_flags & VM_SHARED))
-               if (vma_needs_reservation(h, vma, address) < 0) {
+               if (vma_has_reserves(h, vma, address) < 0) {
                        ret = VM_FAULT_OOM;
                        goto backout_unlocked;
                }
@@ -2860,7 +2854,7 @@ int hugetlb_fault(struct mm_struct *mm, struct 
vm_area_struct *vma,
         * consumed.
         */
        if ((flags & FAULT_FLAG_WRITE) && !huge_pte_write(entry)) {
-               if (vma_needs_reservation(h, vma, address) < 0) {
+               if (vma_has_reserves(h, vma, address) < 0) {
                        ret = VM_FAULT_OOM;
                        goto out_mutex;
                }
-- 
1.7.9.5

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