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Subject[PATCH 09/18] mm, hugetlb: unify has_reserve and avoid_reserve to use_reserve
Date
Currently, we have two variable to represent whether we can use reserved
page or not, has_reserve and avoid_reserve, respectively.
These have same meaning, so we can unify them to use_reserve.
This makes no functinoal difference, is just for clean-up.

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

diff --git a/mm/hugetlb.c b/mm/hugetlb.c
index 749629e..a66226e 100644
--- a/mm/hugetlb.c
+++ b/mm/hugetlb.c
@@ -572,8 +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 has_reserve, int avoid_reserve)
+ unsigned long address, int use_reserve)
{
struct page *page = NULL;
struct mempolicy *mpol;
@@ -586,13 +585,11 @@ 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.
+ * Or, when parent process do COW, we cannot use reserved page.
+ * In this case, ensure enough pages are in the pool.
*/
- if (!has_reserve && h->free_huge_pages - h->resv_huge_pages == 0)
- return NULL;
-
- /* If reserves cannot be used, ensure enough pages are in the pool */
- if (avoid_reserve && h->free_huge_pages - h->resv_huge_pages == 0)
+ if (!use_reserve && h->free_huge_pages - h->resv_huge_pages == 0)
return NULL;

retry_cpuset:
@@ -605,9 +602,7 @@ retry_cpuset:
if (cpuset_zone_allowed_softwall(zone, htlb_alloc_mask)) {
page = dequeue_huge_page_node(h, zone_to_nid(zone));
if (page) {
- if (avoid_reserve)
- break;
- if (!has_reserve)
+ if (!use_reserve)
break;

h->resv_huge_pages--;
@@ -1133,7 +1128,7 @@ 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;
- int ret, idx, has_reserve;
+ int ret, idx, use_reserve;
struct hugetlb_cgroup *h_cg;

idx = hstate_index(h);
@@ -1145,22 +1140,22 @@ static struct page *alloc_huge_page(struct vm_area_struct *vma,
* need pages and subpool limit allocated allocated if no reserve
* mapping overlaps.
*/
- has_reserve = vma_has_reserves(h, vma, addr);
- if (has_reserve < 0)
+ use_reserve = vma_has_reserves(h, vma, addr);
+ if (use_reserve < 0)
return ERR_PTR(-ENOMEM);

- if ((!has_reserve || avoid_reserve)
- && (hugepage_subpool_get_pages(spool, 1) < 0))
+ use_reserve = use_reserve && !avoid_reserve;
+ if (!use_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) {
- if (!has_reserve || avoid_reserve)
+ if (!use_reserve)
hugepage_subpool_put_pages(spool, 1);
return ERR_PTR(-ENOSPC);
}
spin_lock(&hugetlb_lock);
- page = dequeue_huge_page_vma(h, vma, addr, has_reserve, avoid_reserve);
+ page = dequeue_huge_page_vma(h, vma, addr, use_reserve);
if (!page) {
spin_unlock(&hugetlb_lock);
page = alloc_buddy_huge_page(h, NUMA_NO_NODE);
@@ -1168,7 +1163,7 @@ static struct page *alloc_huge_page(struct vm_area_struct *vma,
hugetlb_cgroup_uncharge_cgroup(idx,
pages_per_huge_page(h),
h_cg);
- if (!has_reserve || avoid_reserve)
+ if (!use_reserve)
hugepage_subpool_put_pages(spool, 1);
return ERR_PTR(-ENOSPC);
}
--
1.7.9.5


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