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Subject[RFC 2/3] hugetlbfs: coordinate global and subpool reserve accounting
Date
If the pages for a subpool are reserved, then the reservations have
already been accounted for in the global pool. Therefore, when
requesting a new reservation (such as for a mapping) for the subpool
do not count again in global pool. However, when actually allocating
a page for the subpool decrement gobal reserve count to correspond to
with decrement in global free pages.

Signed-off-by: Mike Kravetz <mike.kravetz@oracle.com>
---
mm/hugetlb.c | 20 +++++++++++++-------
1 file changed, 13 insertions(+), 7 deletions(-)

diff --git a/mm/hugetlb.c b/mm/hugetlb.c
index c6adf65..4ef8379 100644
--- a/mm/hugetlb.c
+++ b/mm/hugetlb.c
@@ -879,7 +879,7 @@ void free_huge_page(struct page *page)
spin_lock(&hugetlb_lock);
hugetlb_cgroup_uncharge_page(hstate_index(h),
pages_per_huge_page(h), page);
- if (restore_reserve)
+ if (restore_reserve || subpool_reserved(spool))
h->resv_huge_pages++;

if (h->surplus_huge_pages_node[nid]) {
@@ -2466,7 +2466,8 @@ static void hugetlb_vm_op_close(struct vm_area_struct *vma)
kref_put(&resv->refs, resv_map_release);

if (reserve) {
- hugetlb_acct_memory(h, -reserve);
+ if (!subpool_reserved(spool))
+ hugetlb_acct_memory(h, -reserve);
hugepage_subpool_put_pages(spool, reserve);
}
}
@@ -3444,10 +3445,14 @@ int hugetlb_reserve_pages(struct inode *inode,
* Check enough hugepages are available for the reservation.
* Hand the pages back to the subpool if there are not
*/
- ret = hugetlb_acct_memory(h, chg);
- if (ret < 0) {
- hugepage_subpool_put_pages(spool, chg);
- goto out_err;
+ if (subpool_reserved(spool))
+ ret = 0;
+ else {
+ ret = hugetlb_acct_memory(h, chg);
+ if (ret < 0) {
+ hugepage_subpool_put_pages(spool, chg);
+ goto out_err;
+ }
}

/*
@@ -3483,7 +3488,8 @@ void hugetlb_unreserve_pages(struct inode *inode, long offset, long freed)
inode->i_blocks -= (blocks_per_huge_page(h) * freed);
spin_unlock(&inode->i_lock);

- hugepage_subpool_put_pages(spool, (chg - freed));
+ if (!subpool_reserved(spool))
+ hugepage_subpool_put_pages(spool, (chg - freed));
hugetlb_acct_memory(h, -(chg - freed));
}

--
2.1.0


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