Messages in this thread | | | Subject | Re: [PATCH v2 4/4] hugetlb: add hugetlb demote page support | From | David Hildenbrand <> | Date | Fri, 24 Sep 2021 11:44:24 +0200 |
| |
On 23.09.21 19:53, Mike Kravetz wrote: > Demote page functionality will split a huge page into a number of huge > pages of a smaller size. For example, on x86 a 1GB huge page can be > demoted into 512 2M huge pages. Demotion is done 'in place' by simply > splitting the huge page. > > Added '*_for_demote' wrappers for remove_hugetlb_page, > destroy_compound_gigantic_page and prep_compound_gigantic_page for use > by demote code. > > Signed-off-by: Mike Kravetz <mike.kravetz@oracle.com> > --- > mm/hugetlb.c | 79 +++++++++++++++++++++++++++++++++++++++++++++++++--- > 1 file changed, 75 insertions(+), 4 deletions(-) > > diff --git a/mm/hugetlb.c b/mm/hugetlb.c > index 2317d411243d..ab7bd0434057 100644 > --- a/mm/hugetlb.c > +++ b/mm/hugetlb.c > @@ -1260,7 +1260,7 @@ static int hstate_next_node_to_free(struct hstate *h, nodemask_t *nodes_allowed) > ((node = hstate_next_node_to_free(hs, mask)) || 1); \ > nr_nodes--) > > -#ifdef CONFIG_ARCH_HAS_GIGANTIC_PAGE > +/* used to demote non-gigantic_huge pages as well */ > static void __destroy_compound_gigantic_page(struct page *page, > unsigned int order, bool demote) > { > @@ -1283,6 +1283,13 @@ static void __destroy_compound_gigantic_page(struct page *page, > __ClearPageHead(page); > } > > +static void destroy_compound_gigantic_page_for_demote(struct page *page, > + unsigned int order) > +{ > + __destroy_compound_gigantic_page(page, order, true); > +} > + > +#ifdef CONFIG_ARCH_HAS_GIGANTIC_PAGE > static void destroy_compound_gigantic_page(struct page *page, > unsigned int order) > { > @@ -1428,6 +1435,12 @@ static void remove_hugetlb_page(struct hstate *h, struct page *page, > __remove_hugetlb_page(h, page, adjust_surplus, false); > } > > +static void remove_hugetlb_page_for_demote(struct hstate *h, struct page *page, > + bool adjust_surplus) > +{ > + __remove_hugetlb_page(h, page, adjust_surplus, true); > +} > + > static void add_hugetlb_page(struct hstate *h, struct page *page, > bool adjust_surplus) > { > @@ -1777,6 +1790,12 @@ static bool prep_compound_gigantic_page(struct page *page, unsigned int order) > return __prep_compound_gigantic_page(page, order, false); > } > > +static bool prep_compound_gigantic_page_for_demote(struct page *page, > + unsigned int order) > +{ > + return __prep_compound_gigantic_page(page, order, true); > +} > + > /* > * PageHuge() only returns true for hugetlbfs pages, but not for normal or > * transparent huge pages. See the PageTransHuge() documentation for more > @@ -3298,9 +3317,55 @@ static int set_max_huge_pages(struct hstate *h, unsigned long count, int nid, > return 0; > } > > +static int demote_free_huge_page(struct hstate *h, struct page *page) > +{ > + int i, nid = page_to_nid(page); > + struct hstate *target_hstate; > + bool cma_page = HPageCma(page); > + > + target_hstate = size_to_hstate(PAGE_SIZE << h->demote_order); > + > + remove_hugetlb_page_for_demote(h, page, false); > + spin_unlock_irq(&hugetlb_lock); > + > + if (alloc_huge_page_vmemmap(h, page)) { > + /* Allocation of vmemmmap failed, we can not demote page */ > + spin_lock_irq(&hugetlb_lock); > + set_page_refcounted(page); > + add_hugetlb_page(h, page, false);
I dislike using 0/1 as return values as it will just hide the actual issue.
This here would be -ENOMEM, right?
-- Thanks,
David / dhildenb
| |