To implement a graceful failure handling, we need to know whether
allocation request is for reserved pool or not, on higher level.
In this patch, we just move up vma_has_reseve() to caller function
in order to know it. There is no functional change.
Following patches implement a grace failure handling and remove
a hugetlb_instantiation_mutex.

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

diff --git a/mm/hugetlb.c b/mm/hugetlb.c
index a66226e..5f31ca5 100644
--- a/mm/hugetlb.c
+++ b/mm/hugetlb.c
@@ -1123,12 +1123,12 @@ static void vma_commit_reservation(struct hstate *h,
 }
 
 static struct page *alloc_huge_page(struct vm_area_struct *vma,
-                                   unsigned long addr, int avoid_reserve)
+                                   unsigned long addr, int use_reserve)
 {
        struct hugepage_subpool *spool = subpool_vma(vma);
        struct hstate *h = hstate_vma(vma);
        struct page *page;
-       int ret, idx, use_reserve;
+       int ret, idx;
        struct hugetlb_cgroup *h_cg;
 
        idx = hstate_index(h);
@@ -1140,11 +1140,6 @@ static struct page *alloc_huge_page(struct 
vm_area_struct *vma,
         * need pages and subpool limit allocated allocated if no reserve
         * mapping overlaps.
         */
-       use_reserve = vma_has_reserves(h, vma, addr);
-       if (use_reserve < 0)
-               return ERR_PTR(-ENOMEM);
-
-       use_reserve = use_reserve && !avoid_reserve;
        if (!use_reserve && (hugepage_subpool_get_pages(spool, 1) < 0))
                        return ERR_PTR(-ENOSPC);
 
@@ -2520,7 +2515,7 @@ static int hugetlb_cow(struct mm_struct *mm, struct 
vm_area_struct *vma,
 {
        struct hstate *h = hstate_vma(vma);
        struct page *old_page, *new_page;
-       int outside_reserve = 0;
+       int use_reserve, outside_reserve = 0;
        unsigned long mmun_start;       /* For mmu_notifiers */
        unsigned long mmun_end;         /* For mmu_notifiers */
 
@@ -2553,7 +2548,18 @@ retry_avoidcopy:
 
        /* Drop page_table_lock as buddy allocator may be called */
        spin_unlock(&mm->page_table_lock);
-       new_page = alloc_huge_page(vma, address, outside_reserve);
+
+       use_reserve = vma_has_reserves(h, vma, address);
+       if (use_reserve == -ENOMEM) {
+               page_cache_release(old_page);
+
+               /* Caller expects lock to be held */
+               spin_lock(&mm->page_table_lock);
+               return VM_FAULT_OOM;
+       }
+       use_reserve = use_reserve && !outside_reserve;
+
+       new_page = alloc_huge_page(vma, address, use_reserve);
 
        if (IS_ERR(new_page)) {
                long err = PTR_ERR(new_page);
@@ -2679,6 +2685,7 @@ static int hugetlb_no_page(struct mm_struct *mm, struct 
vm_area_struct *vma,
        struct page *page;
        struct address_space *mapping;
        pte_t new_pte;
+       int use_reserve = 0;
 
        /*
         * Currently, we are forced to kill the process in the event the
@@ -2704,7 +2711,14 @@ retry:
                size = i_size_read(mapping->host) >> huge_page_shift(h);
                if (idx >= size)
                        goto out;
-               page = alloc_huge_page(vma, address, 0);
+
+               use_reserve = vma_has_reserves(h, vma, address);
+               if (use_reserve == -ENOMEM) {
+                       ret = VM_FAULT_OOM;
+                       goto out;
+               }
+
+               page = alloc_huge_page(vma, address, use_reserve);
                if (IS_ERR(page)) {
                        ret = PTR_ERR(page);
                        if (ret == -ENOMEM)
-- 
1.7.9.5

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