On Wed, May 14, 2025 at 4:43 PM Ackerley Tng <ackerleytng@google.com> wrote:
>
> Previously, gbl_chg was passed from alloc_hugetlb_folio() into
> dequeue_hugetlb_folio_vma(), leaking the concept of gbl_chg into
> dequeue_hugetlb_folio_vma().
>
> This patch consolidates the interpretation of gbl_chg into
> alloc_hugetlb_folio(), also renaming dequeue_hugetlb_folio_vma() to
> dequeue_hugetlb_folio() so dequeue_hugetlb_folio() can just focus on
> dequeuing a folio.
>
> Change-Id: I31bf48af2400b6e13b44d03c8be22ce1a9092a9c
> Signed-off-by: Ackerley Tng <ackerleytng@google.com>
I think I agree with Binbin[1] to either put the rename of
dequeue_hugetlb_folio{_vma => }() in its own patch or drop it
entirely.
I think the rename would 100% make sense if all of the
dequeue_hugetlb_folio*() functions were called from
dequeue_hugetlb_folio_vma() (i.e., after this patch,
dequeue_hugetlb_folio() was always the entry point to dequeue a
folio), but in fact dequeue_hugetlb_folio_nodemask() is not always
called from dequeue_hugetlb_folio_vma().
I don't feel strongly at all, either way the name is not confusing. So
feel free to add:
Reviewed-by: James Houghton <jthoughton@google.com>
[1]: https://lore.kernel.org/all/ad77da83-0e6e-47a1-abe7-8cfdfce8b254@linux.intel.com/
> ---
> mm/hugetlb.c | 28 +++++++++++-----------------
> 1 file changed, 11 insertions(+), 17 deletions(-)
>
> diff --git a/mm/hugetlb.c b/mm/hugetlb.c
> index 6ea1be71aa42..b843e869496f 100644
> --- a/mm/hugetlb.c
> +++ b/mm/hugetlb.c
> @@ -1364,9 +1364,9 @@ static unsigned long available_huge_pages(struct hstate *h)
> return h->free_huge_pages - h->resv_huge_pages;
> }
>
> -static struct folio *dequeue_hugetlb_folio_vma(struct hstate *h,
> - struct vm_area_struct *vma,
> - unsigned long address, long gbl_chg)
> +static struct folio *dequeue_hugetlb_folio(struct hstate *h,
> + struct vm_area_struct *vma,
> + unsigned long address)
> {
> struct folio *folio = NULL;
> struct mempolicy *mpol;
> @@ -1374,13 +1374,6 @@ static struct folio *dequeue_hugetlb_folio_vma(struct hstate *h,
> nodemask_t *nodemask;
> int nid;
>
> - /*
> - * gbl_chg==1 means the allocation requires a new page that was not
> - * reserved before. Making sure there's at least one free page.
> - */
> - if (gbl_chg && !available_huge_pages(h))
> - goto err;
> -
> gfp_mask = htlb_alloc_mask(h);
> nid = huge_node(vma, address, gfp_mask, &mpol, &nodemask);
>
> @@ -1398,9 +1391,6 @@ static struct folio *dequeue_hugetlb_folio_vma(struct hstate *h,
>
> mpol_cond_put(mpol);
> return folio;
> -
> -err:
> - return NULL;
> }
>
> /*
> @@ -3074,12 +3064,16 @@ struct folio *alloc_hugetlb_folio(struct vm_area_struct *vma,
> goto out_uncharge_cgroup_reservation;
>
> spin_lock_irq(&hugetlb_lock);
> +
> /*
> - * 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.
> + * 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 = dequeue_hugetlb_folio_vma(h, vma, addr, gbl_chg);
> + folio = NULL;
> + if (!gbl_chg || available_huge_pages(h))
> + folio = dequeue_hugetlb_folio(h, vma, addr);
> +
> if (!folio) {
> spin_unlock_irq(&hugetlb_lock);
> folio = alloc_buddy_hugetlb_folio_with_mpol(h, vma, addr);
> --
> 2.49.0.1045.g170613ef41-goog
>