Re: [PATCH v2 3/9] mm/hugetlb_cgroup: convert set_hugetlb_cgroup*() to folios

[Muchun Song <muchun.song@linux.dev>]

> On Nov 2, 2022, at 06:30, Sidhartha Kumar <sidhartha.kumar@oracle.com> wrote:
> 
> Allows __prep_new_huge_page() to operate on a folio by converting
> set_hugetlb_cgroup*() to take in a folio.
> 
> Signed-off-by: Sidhartha Kumar <sidhartha.kumar@oracle.com>
> ---
> include/linux/hugetlb_cgroup.h | 12 ++++++------
> mm/hugetlb.c                   | 33 +++++++++++++++++++--------------
> mm/hugetlb_cgroup.c            | 11 ++++++-----
> 3 files changed, 31 insertions(+), 25 deletions(-)
> 
> diff --git a/include/linux/hugetlb_cgroup.h b/include/linux/hugetlb_cgroup.h
> index feb2edafc8b6..a7e3540f7f38 100644
> --- a/include/linux/hugetlb_cgroup.h
> +++ b/include/linux/hugetlb_cgroup.h
> @@ -112,16 +112,16 @@ static inline void __set_hugetlb_cgroup(struct folio *folio,
> (unsigned long)h_cg);
> }
> 
> -static inline void set_hugetlb_cgroup(struct page *page,
> +static inline void set_hugetlb_cgroup(struct folio *folio,
>     struct hugetlb_cgroup *h_cg)
> {
> - __set_hugetlb_cgroup(page_folio(page), h_cg, false);
> + __set_hugetlb_cgroup(folio, h_cg, false);
> }
> 
> -static inline void set_hugetlb_cgroup_rsvd(struct page *page,
> +static inline void set_hugetlb_cgroup_rsvd(struct folio *folio,
>  struct hugetlb_cgroup *h_cg)
> {
> - __set_hugetlb_cgroup(page_folio(page), h_cg, true);
> + __set_hugetlb_cgroup(folio, h_cg, true);
> }
> 
> static inline bool hugetlb_cgroup_disabled(void)
> @@ -199,12 +199,12 @@ hugetlb_cgroup_from_folio_rsvd(struct folio *folio)
> return NULL;
> }
> 
> -static inline void set_hugetlb_cgroup(struct page *page,
> +static inline void set_hugetlb_cgroup(struct folio *folio,
>     struct hugetlb_cgroup *h_cg)
> {
> }
> 
> -static inline void set_hugetlb_cgroup_rsvd(struct page *page,
> +static inline void set_hugetlb_cgroup_rsvd(struct folio *folio,
>  struct hugetlb_cgroup *h_cg)
> {
> }
> diff --git a/mm/hugetlb.c b/mm/hugetlb.c
> index 27b87dc85c48..a6384fb0b57f 100644
> --- a/mm/hugetlb.c
> +++ b/mm/hugetlb.c
> @@ -1758,19 +1758,21 @@ static void __prep_account_new_huge_page(struct hstate *h, int nid)
> h->nr_huge_pages_node[nid]++;
> }
> 
> -static void __prep_new_huge_page(struct hstate *h, struct page *page)
> +static void __prep_new_hugetlb_folio(struct hstate *h, struct folio *folio)
> {
> - hugetlb_vmemmap_optimize(h, page);
> - INIT_LIST_HEAD(&page->lru);
> - set_compound_page_dtor(page, HUGETLB_PAGE_DTOR);
> - hugetlb_set_page_subpool(page, NULL);
> - set_hugetlb_cgroup(page, NULL);
> - set_hugetlb_cgroup_rsvd(page, NULL);
> + hugetlb_vmemmap_optimize(h, &folio->page);
> + INIT_LIST_HEAD(&folio->lru);
> + folio->_folio_dtor = HUGETLB_PAGE_DTOR;

Seems like a variant of set_compound_page_dtor() for folio is missing,
e.g. set_large_folio_dtor(). It's better to add it in this series.

Thanks.

> + hugetlb_set_folio_subpool(folio, NULL);
> + set_hugetlb_cgroup(folio, NULL);
> + set_hugetlb_cgroup_rsvd(folio, NULL);
> }
> 
> static void prep_new_huge_page(struct hstate *h, struct page *page, int nid)
> {
> - __prep_new_huge_page(h, page);
> + struct folio *folio = page_folio(page);
> +
> + __prep_new_hugetlb_folio(h, folio);
> spin_lock_irq(&hugetlb_lock);
> __prep_account_new_huge_page(h, nid);
> spin_unlock_irq(&hugetlb_lock);
> @@ -2731,8 +2733,10 @@ static int alloc_and_dissolve_huge_page(struct hstate *h, struct page *old_page,
> struct list_head *list)
> {
> gfp_t gfp_mask = htlb_alloc_mask(h) | __GFP_THISNODE;
> - int nid = page_to_nid(old_page);
> + struct folio *old_folio = page_folio(old_page);
> + int nid = folio_nid(old_folio);
> struct page *new_page;
> + struct folio *new_folio;
> int ret = 0;
> 
> /*
> @@ -2745,16 +2749,17 @@ static int alloc_and_dissolve_huge_page(struct hstate *h, struct page *old_page,
> new_page = alloc_buddy_huge_page(h, gfp_mask, nid, NULL, NULL);
> if (!new_page)
> return -ENOMEM;
> - __prep_new_huge_page(h, new_page);
> + new_folio = page_folio(new_page);
> + __prep_new_hugetlb_folio(h, new_folio);
> 
> retry:
> spin_lock_irq(&hugetlb_lock);
> - if (!PageHuge(old_page)) {
> + if (!folio_test_hugetlb(old_folio)) {
> /*
> * Freed from under us. Drop new_page too.
> */
> goto free_new;
> - } else if (page_count(old_page)) {
> + } else if (folio_ref_count(old_folio)) {
> /*
> * Someone has grabbed the page, try to isolate it here.
> * Fail with -EBUSY if not possible.
> @@ -2763,7 +2768,7 @@ static int alloc_and_dissolve_huge_page(struct hstate *h, struct page *old_page,
> ret = isolate_hugetlb(old_page, list);
> spin_lock_irq(&hugetlb_lock);
> goto free_new;
> - } else if (!HPageFreed(old_page)) {
> + } else if (!folio_test_hugetlb_freed(old_folio)) {
> /*
> * Page's refcount is 0 but it has not been enqueued in the
> * freelist yet. Race window is small, so we can succeed here if
> @@ -2801,7 +2806,7 @@ static int alloc_and_dissolve_huge_page(struct hstate *h, struct page *old_page,
> free_new:
> spin_unlock_irq(&hugetlb_lock);
> /* Page has a zero ref count, but needs a ref to be freed */
> - set_page_refcounted(new_page);
> + folio_ref_unfreeze(new_folio, 1);
> update_and_free_page(h, new_page, false);
> 
> return ret;
> diff --git a/mm/hugetlb_cgroup.c b/mm/hugetlb_cgroup.c
> index 600c98560a0f..692b23b5d423 100644
> --- a/mm/hugetlb_cgroup.c
> +++ b/mm/hugetlb_cgroup.c
> @@ -212,7 +212,7 @@ static void hugetlb_cgroup_move_parent(int idx, struct hugetlb_cgroup *h_cg,
> /* Take the pages off the local counter */
> page_counter_cancel(counter, nr_pages);
> 
> - set_hugetlb_cgroup(page, parent);
> + set_hugetlb_cgroup(folio, parent);
> out:
> return;
> }
> @@ -894,6 +894,7 @@ void hugetlb_cgroup_migrate(struct page *oldhpage, struct page *newhpage)
> struct hugetlb_cgroup *h_cg_rsvd;
> struct hstate *h = page_hstate(oldhpage);
> struct folio *old_folio = page_folio(oldhpage);
> + struct folio *new_folio = page_folio(newhpage);
> 
> if (hugetlb_cgroup_disabled())
> return;
> @@ -901,12 +902,12 @@ void hugetlb_cgroup_migrate(struct page *oldhpage, struct page *newhpage)
> spin_lock_irq(&hugetlb_lock);
> h_cg = hugetlb_cgroup_from_folio(old_folio);
> h_cg_rsvd = hugetlb_cgroup_from_folio_rsvd(old_folio);
> - set_hugetlb_cgroup(oldhpage, NULL);
> - set_hugetlb_cgroup_rsvd(oldhpage, NULL);
> + set_hugetlb_cgroup(old_folio, NULL);
> + set_hugetlb_cgroup_rsvd(old_folio, NULL);
> 
> /* move the h_cg details to new cgroup */
> - set_hugetlb_cgroup(newhpage, h_cg);
> - set_hugetlb_cgroup_rsvd(newhpage, h_cg_rsvd);
> + set_hugetlb_cgroup(new_folio, h_cg);
> + set_hugetlb_cgroup_rsvd(new_folio, h_cg_rsvd);
> list_move(&newhpage->lru, &h->hugepage_activelist);
> spin_unlock_irq(&hugetlb_lock);
> return;
> -- 
> 2.31.1
> 
>