On Fri 19-03-21 15:42:04, 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. > > 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.
I like this! Counters handling both in __free_huge_page and update_and_free_page is really confusing. > Signed-off-by: Mike Kravetz <[email protected]> > --- > mm/hugetlb.c | 70 ++++++++++++++++++++++++++++++++++------------------ > 1 file changed, 46 insertions(+), 24 deletions(-) > > diff --git a/mm/hugetlb.c b/mm/hugetlb.c > index c537274c2a38..ae185d3315e0 100644 > --- a/mm/hugetlb.c > +++ b/mm/hugetlb.c > @@ -1306,6 +1306,46 @@ 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. > + * NOTE: hugetlb specific page flags stored in page->private are not > + * automatically cleared. These flags may be used in routines > + * which operate on the resulting compound 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); > + I think we want lockdep_assert_held here. Lockdep asserts are not used in this code but now that you are touching it then it is probably better to start adding them. What do you think? > + 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]--; > +} -- Michal Hocko SUSE Labs
