Areas hole punched by fallocate will not have entries in the
region/reserve map. However, shared mappings with min_size subpool
reservations may still have reserved pages. alloc_huge_page needs
to handle this special case and do the proper accounting.
Signed-off-by: Mike Kravetz <mike.kravetz@xxxxxxxxxx>
---
mm/hugetlb.c | 54 +++++++++++++++++++++++++++++++++++++++---------------
1 file changed, 39 insertions(+), 15 deletions(-)
diff --git a/mm/hugetlb.c b/mm/hugetlb.c
index f9d3faf..efcd58c 100644
--- a/mm/hugetlb.c
+++ b/mm/hugetlb.c
@@ -1735,34 +1735,58 @@ 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;
- long chg, commit;
+ long map_chg, map_commit;
+ long gbl_chg;
int ret, idx;
struct hugetlb_cgroup *h_cg;
idx = hstate_index(h);
/*
- * Processes that did not create the mapping will have no
- * reserves and will not have accounted against subpool
- * limit. Check that the subpool limit can be made before
- * satisfying the allocation MAP_NORESERVE mappings may also
- * need pages and subpool limit allocated allocated if no reserve
- * mapping overlaps.
+ * Examine the region/reserve map to determine if the process
+ * has a reservation for the page to be allocated. A return
+ * code of zero indicates a reservation exists (no change).
*/
- chg = vma_needs_reservation(h, vma, addr);
- if (chg < 0)
+ map_chg = gbl_chg = vma_needs_reservation(h, vma, addr);
+ if (map_chg < 0)
return ERR_PTR(-ENOMEM);
- if (chg || avoid_reserve)
- if (hugepage_subpool_get_pages(spool, 1) < 0) {
+
+ /*
+ * Processes that did not create the mapping will have no
+ * reserves as indicated by the region/reserve map. Check
+ * that the allocation will not exceed the subpool limit.
+ * Allocations for MAP_NORESERVE mappings also need to be
+ * checked against any subpool limit.
+ */
+ if (map_chg || avoid_reserve) {
+ gbl_chg = hugepage_subpool_get_pages(spool, 1);
+ if (gbl_chg < 0) {
vma_end_reservation(h, vma, addr);
return ERR_PTR(-ENOSPC);
}
+ /*
+ * Even though there was no reservation in the region/reserve
+ * map, there could be reservations associated with the
+ * subpool that can be used. This would be indicated if the
+ * return value of hugepage_subpool_get_pages() is zero.
+ * However, if avoid_reserve is specified we still avoid even
+ * the subpool reservations.
+ */
+ if (avoid_reserve)
+ gbl_chg = 1;
+ }
+
ret = hugetlb_cgroup_charge_cgroup(idx, pages_per_huge_page(h), &h_cg);
if (ret)
goto out_subpool_put;
spin_lock(&hugetlb_lock);
- page = dequeue_huge_page_vma(h, vma, addr, avoid_reserve, chg);
+ /*
+ * glb_chg is passed to indicate whether or not a page must be taken
+ * from the global free pool (global change). gbl_chg == 0 indicates
+ * a reservation exists for the allocation.
+ */
+ page = dequeue_huge_page_vma(h, vma, addr, avoid_reserve, gbl_chg);
if (!page) {
spin_unlock(&hugetlb_lock);
page = alloc_buddy_huge_page(h, NUMA_NO_NODE);
@@ -1778,8 +1802,8 @@ static struct page *alloc_huge_page(struct vm_area_struct *vma,
set_page_private(page, (unsigned long)spool);
- commit = vma_commit_reservation(h, vma, addr);
- if (unlikely(chg > commit)) {
+ map_commit = vma_commit_reservation(h, vma, addr);
+ if (unlikely(map_chg > map_commit)) {
/*
* The page was added to the reservation map between
* vma_needs_reservation and vma_commit_reservation.
@@ -1799,7 +1823,7 @@ static 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);
out_subpool_put:
- if (chg || avoid_reserve)
+ if (map_chg || avoid_reserve)
hugepage_subpool_put_pages(spool, 1);
vma_end_reservation(h, vma, addr);
return ERR_PTR(-ENOSPC);
--
2.1.0
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