On Mon 05-04-21 16:00:40, Mike Kravetz wrote: > With the introduction of remove_hugetlb_page(), there is no need for > update_and_free_page to hold the hugetlb lock. Change all callers to > drop the lock before calling. > > With additional code modifications, this will allow loops which decrease > the huge page pool to drop the hugetlb_lock with each page to reduce > long hold times. > > The ugly unlock/lock cycle in free_pool_huge_page will be removed in > a subsequent patch which restructures free_pool_huge_page. > > Signed-off-by: Mike Kravetz <[email protected]>
Still looks good. Acked-by: Michal Hocko <[email protected]> > --- > mm/hugetlb.c | 43 +++++++++++++++++++++++++++++++++---------- > 1 file changed, 33 insertions(+), 10 deletions(-) > > diff --git a/mm/hugetlb.c b/mm/hugetlb.c > index df2a3d1f632b..be6031a8e2a9 100644 > --- a/mm/hugetlb.c > +++ b/mm/hugetlb.c > @@ -1446,16 +1446,18 @@ static void __free_huge_page(struct page *page) > > if (HPageTemporary(page)) { > remove_hugetlb_page(h, page, false); > + spin_unlock(&hugetlb_lock); > update_and_free_page(h, page); > } else if (h->surplus_huge_pages_node[nid]) { > /* remove the page from active list */ > remove_hugetlb_page(h, page, true); > + spin_unlock(&hugetlb_lock); > update_and_free_page(h, page); > } else { > arch_clear_hugepage_flags(page); > enqueue_huge_page(h, page); > + spin_unlock(&hugetlb_lock); > } > - spin_unlock(&hugetlb_lock); > } > > /* > @@ -1736,7 +1738,13 @@ static int free_pool_huge_page(struct hstate *h, > nodemask_t *nodes_allowed, > list_entry(h->hugepage_freelists[node].next, > struct page, lru); > remove_hugetlb_page(h, page, acct_surplus); > + /* > + * unlock/lock around update_and_free_page is temporary > + * and will be removed with subsequent patch. > + */ > + spin_unlock(&hugetlb_lock); > update_and_free_page(h, page); > + spin_lock(&hugetlb_lock); > ret = 1; > break; > } > @@ -1805,8 +1813,9 @@ int dissolve_free_huge_page(struct page *page) > } > remove_hugetlb_page(h, page, false); > h->max_huge_pages--; > + spin_unlock(&hugetlb_lock); > update_and_free_page(h, head); > - rc = 0; > + return 0; > } > out: > spin_unlock(&hugetlb_lock); > @@ -2291,6 +2300,7 @@ static int alloc_and_dissolve_huge_page(struct hstate > *h, struct page *old_page, > gfp_t gfp_mask = htlb_alloc_mask(h) | __GFP_THISNODE; > int nid = page_to_nid(old_page); > struct page *new_page; > + struct page *page_to_free; > int ret = 0; > > /* > @@ -2313,16 +2323,16 @@ 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; > + page_to_free = new_page; > + goto unlock_free; > } else if (page_count(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); > + update_and_free_page(h, new_page); > if (!isolate_huge_page(old_page, list)) > ret = -EBUSY; > return ret; > @@ -2344,11 +2354,12 @@ static int alloc_and_dissolve_huge_page(struct hstate > *h, struct page *old_page, > * enqueue_huge_page for new page. Net result is no change. > */ > remove_hugetlb_page(h, old_page, false); > - update_and_free_page(h, old_page); > enqueue_huge_page(h, new_page); > + page_to_free = old_page; > } > -unlock: > +unlock_free: > spin_unlock(&hugetlb_lock); > + update_and_free_page(h, page_to_free); > > return ret; > } > @@ -2671,22 +2682,34 @@ static void try_to_free_low(struct hstate *h, > unsigned long count, > nodemask_t *nodes_allowed) > { > int i; > + struct page *page, *next; > + LIST_HEAD(page_list); > > if (hstate_is_gigantic(h)) > return; > > + /* > + * Collect pages to be freed on a list, and free after dropping lock > + */ > for_each_node_mask(i, *nodes_allowed) { > - struct page *page, *next; > struct list_head *freel = &h->hugepage_freelists[i]; > list_for_each_entry_safe(page, next, freel, lru) { > if (count >= h->nr_huge_pages) > - return; > + goto out; > if (PageHighMem(page)) > continue; > remove_hugetlb_page(h, page, false); > - update_and_free_page(h, page); > + list_add(&page->lru, &page_list); > } > } > + > +out: > + spin_unlock(&hugetlb_lock); > + list_for_each_entry_safe(page, next, &page_list, lru) { > + update_and_free_page(h, page); > + cond_resched(); > + } > + spin_lock(&hugetlb_lock); > } > #else > static inline void try_to_free_low(struct hstate *h, unsigned long count, > -- > 2.30.2 > -- Michal Hocko SUSE Labs
