linux-kernel - [PATCH v2 7/7] mm/hugetlb: Unify restore reserve accounting for new allocations

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Message-ID: <20250107204002.2683356-8-peterx@redhat.com>
Date: Tue,  7 Jan 2025 15:40:02 -0500
From: Peter Xu <peterx@...hat.com>
To: linux-mm@...ck.org,
	linux-kernel@...r.kernel.org
Cc: Breno Leitao <leitao@...ian.org>,
	Rik van Riel <riel@...riel.com>,
	Muchun Song <muchun.song@...ux.dev>,
	Naoya Horiguchi <nao.horiguchi@...il.com>,
	Roman Gushchin <roman.gushchin@...ux.dev>,
	Ackerley Tng <ackerleytng@...gle.com>,
	Andrew Morton <akpm@...ux-foundation.org>,
	peterx@...hat.com,
	Oscar Salvador <osalvador@...e.de>
Subject: [PATCH v2 7/7] mm/hugetlb: Unify restore reserve accounting for new allocations

Either hugetlb pages dequeued from hstate, or newly allocated from buddy,
would require restore-reserve accounting to be managed properly.  Merge the
two paths on it.  Add a small comment to make it slightly nicer.

Signed-off-by: Peter Xu <peterx@...hat.com>
---
 mm/hugetlb.c | 18 +++++++++---------
 1 file changed, 9 insertions(+), 9 deletions(-)

diff --git a/mm/hugetlb.c b/mm/hugetlb.c
index 922d57e2413a..3b27840de36f 100644
--- a/mm/hugetlb.c
+++ b/mm/hugetlb.c
@@ -1361,11 +1361,6 @@ static struct folio *dequeue_hugetlb_folio_vma(struct hstate *h,
 		folio = dequeue_hugetlb_folio_nodemask(h, gfp_mask,
 							nid, nodemask);
 
-	if (folio && !gbl_chg) {
-		folio_set_hugetlb_restore_reserve(folio);
-		h->resv_huge_pages--;
-	}
-
 	mpol_cond_put(mpol);
 	return folio;
 
@@ -3052,15 +3047,20 @@ struct folio *alloc_hugetlb_folio(struct vm_area_struct *vma,
 		if (!folio)
 			goto out_uncharge_cgroup;
 		spin_lock_irq(&hugetlb_lock);
-		if (!gbl_chg) {
-			folio_set_hugetlb_restore_reserve(folio);
-			h->resv_huge_pages--;
-		}
 		list_add(&folio->lru, &h->hugepage_activelist);
 		folio_ref_unfreeze(folio, 1);
 		/* Fall through */
 	}
 
+	/*
+	 * Either dequeued or buddy-allocated folio needs to add special
+	 * mark to the folio when it consumes a global reservation.
+	 */
+	if (!gbl_chg) {
+		folio_set_hugetlb_restore_reserve(folio);
+		h->resv_huge_pages--;
+	}
+
 	hugetlb_cgroup_commit_charge(idx, pages_per_huge_page(h), h_cg, folio);
 	/* If allocation is not consuming a reservation, also store the
 	 * hugetlb_cgroup pointer on the page.
-- 
2.47.0