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.

Link: https://lkml.kernel.org/r/20250107204002.2683356-8-peterx@redhat.com
Signed-off-by: Peter Xu <peterx@redhat.com>
Cc: Ackerley Tng <ackerleytng@google.com>
Cc: Breno Leitao <leitao@debian.org>
Cc: Muchun Song <muchun.song@linux.dev>
Cc: Naoya Horiguchi <nao.horiguchi@gmail.com>
Cc: Oscar Salvador <osalvador@suse.de>
Cc: Rik van Riel <riel@surriel.com>
Cc: Roman Gushchin <roman.gushchin@linux.dev>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

diff --git a/mm/hugetlb.c b/mm/hugetlb.c
index 8e46798a9dfc2f1a498d7cf2cebd1b29038f4e7f..58c2c54982079adfae08b29e3d1d044176b0c6dc 100644 (file)
--- a/mm/hugetlb.c
+++ b/mm/hugetlb.c
@@ -1365,11 +1365,6 @@ 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;
 
@@ -3056,15 +3051,20 @@ 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.