The comment before dequeuing a folio explains that if gbl_chg == 0, a
reservation exists for the allocation.
In addition, if a vma reservation exists, there's no need to get a
reservation from the subpool, and gbl_chg was set to 0.
This patch replaces both of that with code: subpool_reservation_exists
defaults to false, and if a vma reservation does not exist, a
reservation is sought from the subpool.
Then, the existence of a reservation, whether in the vma or subpool,
is summarized into reservation_exists, which is then used to determine
whether to dequeue a folio.
Signed-off-by: Ackerley Tng <ackerleytng@xxxxxxxxxx>
Change-Id: I52130a0bf9f33e07d320a446cdb3ebfddd9de658
---
mm/hugetlb.c | 28 ++++++++++++----------------
1 file changed, 12 insertions(+), 16 deletions(-)
diff --git a/mm/hugetlb.c b/mm/hugetlb.c
index b843e869496f..597f2b9f62b5 100644
--- a/mm/hugetlb.c
+++ b/mm/hugetlb.c
@@ -2999,8 +2999,10 @@ struct folio *alloc_hugetlb_folio(struct vm_area_struct *vma,
{
struct hugepage_subpool *spool = subpool_vma(vma);
struct hstate *h = hstate_vma(vma);
+ bool subpool_reservation_exists;
+ bool reservation_exists;
struct folio *folio;
- long retval, gbl_chg;
+ long retval;
map_chg_state map_chg;
int ret, idx;
struct hugetlb_cgroup *h_cg = NULL;
@@ -3036,17 +3038,16 @@ struct folio *alloc_hugetlb_folio(struct vm_area_struct *vma,
* that the allocation will not exceed the subpool limit.
* Or if it can get one from the pool reservation directly.
*/
+ subpool_reservation_exists = false;
if (map_chg) {
- gbl_chg = hugepage_subpool_get_pages(spool, 1);
- if (gbl_chg < 0)
+ int npages_req = hugepage_subpool_get_pages(spool, 1);
+
+ if (npages_req < 0)
goto out_end_reservation;
- } else {
- /*
- * If we have the vma reservation ready, no need for extra
- * global reservation.
- */
- gbl_chg = 0;
+
+ subpool_reservation_exists = npages_req == 0;
}
+ reservation_exists = !map_chg || subpool_reservation_exists;
/*
* If this allocation is not consuming a per-vma reservation,
@@ -3065,13 +3066,8 @@ struct folio *alloc_hugetlb_folio(struct vm_area_struct *vma,
spin_lock_irq(&hugetlb_lock);
- /*
- * gbl_chg == 0 indicates a reservation exists for the allocation - so
- * try dequeuing a page. If there are available_huge_pages(), try using
- * them!
- */
folio = NULL;
- if (!gbl_chg || available_huge_pages(h))
+ if (reservation_exists || available_huge_pages(h))
folio = dequeue_hugetlb_folio(h, vma, addr);
if (!folio) {
@@ -3089,7 +3085,7 @@ struct folio *alloc_hugetlb_folio(struct vm_area_struct *vma,
* Either dequeued or buddy-allocated folio needs to add special
* mark to the folio when it consumes a global reservation.
*/
- if (!gbl_chg) {
+ if (reservation_exists) {
folio_set_hugetlb_restore_reserve(folio);
h->resv_huge_pages--;
}
--
2.49.0.1045.g170613ef41-goog
