On Mon, Apr 05, 2021 at 04:00:39PM -0700, Mike Kravetz wrote:
> The new remove_hugetlb_page() routine is designed to remove a hugetlb
> page from hugetlbfs processing. It will remove the page from the active
> or free list, update global counters and set the compound page
> destructor to NULL so that PageHuge() will return false for the 'page'.
> After this call, the 'page' can be treated as a normal compound page or
> a collection of base size pages.
>
> update_and_free_page no longer decrements h->nr_huge_pages{_node} as
> this is performed in remove_hugetlb_page. The only functionality
> performed by update_and_free_page is to free the base pages to the lower
> level allocators.
>
> update_and_free_page is typically called after remove_hugetlb_page.
>
> remove_hugetlb_page is to be called with the hugetlb_lock held.
>
> Creating this routine and separating functionality is in preparation for
> restructuring code to reduce lock hold times. This commit should not
> introduce any changes to functionality.
>
> Signed-off-by: Mike Kravetz <mike.kravetz@xxxxxxxxxx>
Btw, it seems you were just doing fine before realizing that my series
went in.
So, as this seems a rather urgent matter to move forward (for obvious
reasons and also because it holds hotplug-vmemmap stuff), I wonder if
it would make your life easier to just ask Andrew to remove my series
for the time being and give it yours priority.
I can later work on top of that.
> ---
> mm/hugetlb.c | 88 ++++++++++++++++++++++++++++++----------------------
> 1 file changed, 51 insertions(+), 37 deletions(-)
>
> diff --git a/mm/hugetlb.c b/mm/hugetlb.c
> index 8497a3598c86..df2a3d1f632b 100644
> --- a/mm/hugetlb.c
> +++ b/mm/hugetlb.c
> @@ -1055,18 +1055,13 @@ static bool vma_has_reserves(struct vm_area_struct *vma, long chg)
> return false;
> }
>
> -static void __enqueue_huge_page(struct list_head *list, struct page *page)
> -{
> - list_move(&page->lru, list);
> - SetHPageFreed(page);
> -}
> -
> static void enqueue_huge_page(struct hstate *h, struct page *page)
> {
> int nid = page_to_nid(page);
> - __enqueue_huge_page(&h->hugepage_freelists[nid], page);
> + list_move(&page->lru, &h->hugepage_freelists[nid]);
> h->free_huge_pages++;
> h->free_huge_pages_node[nid]++;
> + SetHPageFreed(page);
> }
>
> static struct page *dequeue_huge_page_node_exact(struct hstate *h, int nid)
> @@ -1331,6 +1326,43 @@ static inline void destroy_compound_gigantic_page(struct page *page,
> unsigned int order) { }
> #endif
>
> +/*
> + * Remove hugetlb page from lists, and update dtor so that page appears
> + * as just a compound page. A reference is held on the page.
> + *
> + * Must be called with hugetlb lock held.
> + */
> +static void remove_hugetlb_page(struct hstate *h, struct page *page,
> + bool adjust_surplus)
> +{
> + int nid = page_to_nid(page);
> +
> + if (hstate_is_gigantic(h) && !gigantic_page_runtime_supported())
> + return;
> +
> + list_del(&page->lru);
> +
> + if (HPageFreed(page)) {
> + h->free_huge_pages--;
> + h->free_huge_pages_node[nid]--;
> + ClearHPageFreed(page);
> + }
> + if (adjust_surplus) {
> + h->surplus_huge_pages--;
> + h->surplus_huge_pages_node[nid]--;
> + }
> +
> + VM_BUG_ON_PAGE(hugetlb_cgroup_from_page(page), page);
> + VM_BUG_ON_PAGE(hugetlb_cgroup_from_page_rsvd(page), page);
> +
> + ClearHPageTemporary(page);
> + set_page_refcounted(page);
> + set_compound_page_dtor(page, NULL_COMPOUND_DTOR);
> +
> + h->nr_huge_pages--;
> + h->nr_huge_pages_node[nid]--;
> +}
> +
> static void update_and_free_page(struct hstate *h, struct page *page)
> {
> int i;
> @@ -1339,8 +1371,6 @@ static void update_and_free_page(struct hstate *h, struct page *page)
> if (hstate_is_gigantic(h) && !gigantic_page_runtime_supported())
> return;
>
> - h->nr_huge_pages--;
> - h->nr_huge_pages_node[page_to_nid(page)]--;
> for (i = 0; i < pages_per_huge_page(h);
> i++, subpage = mem_map_next(subpage, page, i)) {
> subpage->flags &= ~(1 << PG_locked | 1 << PG_error |
> @@ -1348,10 +1378,6 @@ static void update_and_free_page(struct hstate *h, struct page *page)
> 1 << PG_active | 1 << PG_private |
> 1 << PG_writeback);
> }
> - VM_BUG_ON_PAGE(hugetlb_cgroup_from_page(page), page);
> - VM_BUG_ON_PAGE(hugetlb_cgroup_from_page_rsvd(page), page);
> - set_compound_page_dtor(page, NULL_COMPOUND_DTOR);
> - set_page_refcounted(page);
> if (hstate_is_gigantic(h)) {
> destroy_compound_gigantic_page(page, huge_page_order(h));
> free_gigantic_page(page, huge_page_order(h));
> @@ -1419,15 +1445,12 @@ static void __free_huge_page(struct page *page)
> h->resv_huge_pages++;
>
> if (HPageTemporary(page)) {
> - list_del(&page->lru);
> - ClearHPageTemporary(page);
> + remove_hugetlb_page(h, page, false);
> update_and_free_page(h, page);
> } else if (h->surplus_huge_pages_node[nid]) {
> /* remove the page from active list */
> - list_del(&page->lru);
> + remove_hugetlb_page(h, page, true);
> update_and_free_page(h, page);
> - h->surplus_huge_pages--;
> - h->surplus_huge_pages_node[nid]--;
> } else {
> arch_clear_hugepage_flags(page);
> enqueue_huge_page(h, page);
> @@ -1712,13 +1735,7 @@ static int free_pool_huge_page(struct hstate *h, nodemask_t *nodes_allowed,
> struct page *page =
> list_entry(h->hugepage_freelists[node].next,
> struct page, lru);
> - list_del(&page->lru);
> - h->free_huge_pages--;
> - h->free_huge_pages_node[node]--;
> - if (acct_surplus) {
> - h->surplus_huge_pages--;
> - h->surplus_huge_pages_node[node]--;
> - }
> + remove_hugetlb_page(h, page, acct_surplus);
> update_and_free_page(h, page);
> ret = 1;
> break;
> @@ -1756,7 +1773,6 @@ int dissolve_free_huge_page(struct page *page)
> if (!page_count(page)) {
> struct page *head = compound_head(page);
> struct hstate *h = page_hstate(head);
> - int nid = page_to_nid(head);
> if (h->free_huge_pages - h->resv_huge_pages == 0)
> goto out;
>
> @@ -1787,9 +1803,7 @@ int dissolve_free_huge_page(struct page *page)
> SetPageHWPoison(page);
> ClearPageHWPoison(head);
> }
> - list_del(&head->lru);
> - h->free_huge_pages--;
> - h->free_huge_pages_node[nid]--;
> + remove_hugetlb_page(h, page, false);
> h->max_huge_pages--;
> update_and_free_page(h, head);
> rc = 0;
> @@ -2298,6 +2312,7 @@ static int alloc_and_dissolve_huge_page(struct hstate *h, struct page *old_page,
> /*
> * Freed from under us. Drop new_page too.
> */
> + remove_hugetlb_page(h, new_page, false);
> update_and_free_page(h, new_page);
> goto unlock;
> } else if (page_count(old_page)) {
> @@ -2305,6 +2320,7 @@ static int alloc_and_dissolve_huge_page(struct hstate *h, struct page *old_page,
> * Someone has grabbed the page, try to isolate it here.
> * Fail with -EBUSY if not possible.
> */
> + remove_hugetlb_page(h, new_page, false);
> update_and_free_page(h, new_page);
> spin_unlock(&hugetlb_lock);
> if (!isolate_huge_page(old_page, list))
> @@ -2323,13 +2339,13 @@ static int alloc_and_dissolve_huge_page(struct hstate *h, struct page *old_page,
> /*
> * Ok, old_page is still a genuine free hugepage. Replace it
> * with the new one.
> + * Note: h->free_huge_pages{_node} counters are decremented
> + * in remove_hugetlb_page for old_page and incremented in
> + * enqueue_huge_page for new page. Net result is no change.
> */
> - list_del(&old_page->lru);
> + remove_hugetlb_page(h, old_page, false);
> update_and_free_page(h, old_page);
> - /*
> - * h->free_huge_pages{_node} counters do not need to be updated.
> - */
> - __enqueue_huge_page(&h->hugepage_freelists[nid], new_page);
> + enqueue_huge_page(h, new_page);
> }
> unlock:
> spin_unlock(&hugetlb_lock);
> @@ -2667,10 +2683,8 @@ static void try_to_free_low(struct hstate *h, unsigned long count,
> return;
> if (PageHighMem(page))
> continue;
> - list_del(&page->lru);
> + remove_hugetlb_page(h, page, false);
> update_and_free_page(h, page);
> - h->free_huge_pages--;
> - h->free_huge_pages_node[page_to_nid(page)]--;
> }
> }
> }
> --
> 2.30.2
>
--
Oscar Salvador
SUSE L3
