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Subject[PATCH v6 7/9] hugetlb_cgroup: support noreserve mappings
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Support MAP_NORESERVE accounting as part of the new counter.

For each hugepage allocation, at allocation time we check if there is
a reservation for this allocation or not. If there is a reservation for
this allocation, then this allocation was charged at reservation time,
and we don't re-account it. If there is no reserevation for this
allocation, we charge the appropriate hugetlb_cgroup.

The hugetlb_cgroup to uncharge for this allocation is stored in
page[3].private. We use new APIs added in an earlier patch to set this
pointer.

---
mm/hugetlb.c | 25 ++++++++++++++++++++++++-
1 file changed, 24 insertions(+), 1 deletion(-)

diff --git a/mm/hugetlb.c b/mm/hugetlb.c
index af336bf227fb6..79b99878ce6f9 100644
--- a/mm/hugetlb.c
+++ b/mm/hugetlb.c
@@ -1217,6 +1217,7 @@ static void update_and_free_page(struct hstate *h, struct page *page)
1 << PG_writeback);
}
VM_BUG_ON_PAGE(hugetlb_cgroup_from_page(page, false), page);
+ VM_BUG_ON_PAGE(hugetlb_cgroup_from_page(page, true), page);
set_compound_page_dtor(page, NULL_COMPOUND_DTOR);
set_page_refcounted(page);
if (hstate_is_gigantic(h)) {
@@ -1328,6 +1329,9 @@ void free_huge_page(struct page *page)
clear_page_huge_active(page);
hugetlb_cgroup_uncharge_page(hstate_index(h), pages_per_huge_page(h),
page, false);
+ hugetlb_cgroup_uncharge_page(hstate_index(h), pages_per_huge_page(h),
+ page, true);
+
if (restore_reserve)
h->resv_huge_pages++;

@@ -1354,6 +1358,7 @@ static void prep_new_huge_page(struct hstate *h, struct page *page, int nid)
set_compound_page_dtor(page, HUGETLB_PAGE_DTOR);
spin_lock(&hugetlb_lock);
set_hugetlb_cgroup(page, NULL, false);
+ set_hugetlb_cgroup(page, NULL, true);
h->nr_huge_pages++;
h->nr_huge_pages_node[nid]++;
spin_unlock(&hugetlb_lock);
@@ -2155,10 +2160,19 @@ struct page *alloc_huge_page(struct vm_area_struct *vma,
gbl_chg = 1;
}

+ /* If this allocation is not consuming a reservation, charge it now.
+ */
+ if (map_chg || avoid_reserve || !vma_resv_map(vma)) {
+ ret = hugetlb_cgroup_charge_cgroup(idx, pages_per_huge_page(h),
+ &h_cg, true);
+ if (ret)
+ goto out_subpool_put;
+ }
+
ret = hugetlb_cgroup_charge_cgroup(idx, pages_per_huge_page(h), &h_cg,
false);
if (ret)
- goto out_subpool_put;
+ goto out_uncharge_cgroup_reservation;

spin_lock(&hugetlb_lock);
/*
@@ -2182,6 +2196,11 @@ struct page *alloc_huge_page(struct vm_area_struct *vma,
}
hugetlb_cgroup_commit_charge(idx, pages_per_huge_page(h), h_cg, page,
false);
+ if (!vma_resv_map(vma) || map_chg || avoid_reserve) {
+ hugetlb_cgroup_commit_charge(idx, pages_per_huge_page(h), h_cg,
+ page, true);
+ }
+
spin_unlock(&hugetlb_lock);

set_page_private(page, (unsigned long)spool);
@@ -2207,6 +2226,10 @@ struct page *alloc_huge_page(struct vm_area_struct *vma,
out_uncharge_cgroup:
hugetlb_cgroup_uncharge_cgroup(idx, pages_per_huge_page(h), h_cg,
false);
+out_uncharge_cgroup_reservation:
+ if (map_chg || avoid_reserve || !vma_resv_map(vma))
+ hugetlb_cgroup_uncharge_cgroup(idx, pages_per_huge_page(h),
+ h_cg, true);
out_subpool_put:
if (map_chg || avoid_reserve)
hugepage_subpool_put_pages(spool, 1);
--
2.23.0.700.g56cf767bdb-goog
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