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SubjectRe: [PATCH v2 13/20] mm, hugetlb: mm, hugetlb: unify chg and avoid_reserve to use_reserve
Date
Joonsoo Kim <iamjoonsoo.kim@lge.com> writes:

> Currently, we have two variable to represent whether we can use reserved
> page or not, chg and avoid_reserve, respectively. With aggregating these,
> we can have more clean code. This makes no functinoal difference.
>
> Signed-off-by: Joonsoo Kim <iamjoonsoo.kim@lge.com>
>
> diff --git a/mm/hugetlb.c b/mm/hugetlb.c
> index 22ceb04..8dff972 100644
> --- a/mm/hugetlb.c
> +++ b/mm/hugetlb.c
> @@ -531,8 +531,7 @@ 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, bool use_reserve)
> {
> struct page *page = NULL;
> struct mempolicy *mpol;
> @@ -546,12 +545,10 @@ 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
> + * Or, when parent process do COW, we cannot use reserved page.
> + * In this case, ensure enough pages are in the pool.
> */
> - if (chg && h->free_huge_pages - h->resv_huge_pages == 0)
> - return NULL;

This hunk would be much easier if you were changing.

if (!vma_has_reserves(vma) &&
h->free_huge_pages - h->resv_huge_pages == 0)
goto err;

ie, !vma_has_reserves(vma) == !use_reserve.

So may be a patch rearragment would help ?. But neverthless.

Reviewed-by: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>

> -
> - /* 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:
> @@ -564,9 +561,7 @@ 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 (chg)
> + if (!use_reserve)
> break;
>
> SetPagePrivate(page);
> @@ -1121,6 +1116,7 @@ static struct page *alloc_huge_page(struct vm_area_struct *vma,
> struct hstate *h = hstate_vma(vma);
> struct page *page;
> long chg;
> + bool use_reserve;
> int ret, idx;
> struct hugetlb_cgroup *h_cg;
>
> @@ -1136,18 +1132,19 @@ static struct page *alloc_huge_page(struct vm_area_struct *vma,
> chg = vma_needs_reservation(h, vma, addr);
> if (chg < 0)
> return ERR_PTR(-ENOMEM);
> - if (chg || avoid_reserve)
> + use_reserve = (!chg && !avoid_reserve);
> + if (!use_reserve)
> if (hugepage_subpool_get_pages(spool, 1))
> return ERR_PTR(-ENOSPC);
>
> ret = hugetlb_cgroup_charge_cgroup(idx, pages_per_huge_page(h), &h_cg);
> if (ret) {
> - if (chg || 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, avoid_reserve, chg);
> + 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);
> @@ -1155,7 +1152,7 @@ static struct page *alloc_huge_page(struct vm_area_struct *vma,
> hugetlb_cgroup_uncharge_cgroup(idx,
> pages_per_huge_page(h),
> h_cg);
> - if (chg || avoid_reserve)
> + if (!use_reserve)
> hugepage_subpool_put_pages(spool, 1);
> return ERR_PTR(-ENOSPC);
> }
> --
> 1.7.9.5



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