From cfb8c75099dbf152db1b075eead5029c5a30ce51 Mon Sep 17 00:00:00 2001 From: Mike Kravetz Date: Wed, 18 Oct 2023 19:31:06 -0700 Subject: hugetlb: perform vmemmap restoration on a list of pages The routine update_and_free_pages_bulk already performs vmemmap restoration on the list of hugetlb pages in a separate step. In preparation for more functionality to be added in this step, create a new routine hugetlb_vmemmap_restore_folios() that will restore vmemmap for a list of folios. This new routine must provide sufficient feedback about errors and actual restoration performed so that update_and_free_pages_bulk can perform optimally. Special care must be taken when encountering an error from hugetlb_vmemmap_restore_folios. We want to continue making as much forward progress as possible. A new routine bulk_vmemmap_restore_error handles this specific situation. Link: https://lkml.kernel.org/r/20231019023113.345257-5-mike.kravetz@oracle.com Signed-off-by: Mike Kravetz Reviewed-by: Muchun Song Cc: Anshuman Khandual Cc: Barry Song <21cnbao@gmail.com> Cc: David Hildenbrand Cc: David Rientjes Cc: James Houghton Cc: Joao Martins Cc: Konrad Dybcio Cc: Matthew Wilcox (Oracle) Cc: Miaohe Lin Cc: Michal Hocko Cc: Naoya Horiguchi Cc: Oscar Salvador Cc: Sergey Senozhatsky Cc: Usama Arif Cc: Xiongchun Duan Signed-off-by: Andrew Morton --- mm/hugetlb.c | 99 +++++++++++++++++++++++++++++++++++++--------------- mm/hugetlb_vmemmap.c | 38 ++++++++++++++++++++ mm/hugetlb_vmemmap.h | 11 ++++++ 3 files changed, 120 insertions(+), 28 deletions(-) (limited to 'mm') diff --git a/mm/hugetlb.c b/mm/hugetlb.c index 8b171f866d0a..cf834bb7f820 100644 --- a/mm/hugetlb.c +++ b/mm/hugetlb.c @@ -1859,50 +1859,93 @@ static void update_and_free_hugetlb_folio(struct hstate *h, struct folio *folio, schedule_work(&free_hpage_work); } -static void update_and_free_pages_bulk(struct hstate *h, struct list_head *list) +static void bulk_vmemmap_restore_error(struct hstate *h, + struct list_head *folio_list, + struct list_head *non_hvo_folios) { struct folio *folio, *t_folio; - bool clear_dtor = false; - /* - * First allocate required vmemmmap (if necessary) for all folios on - * list. If vmemmap can not be allocated, we can not free folio to - * lower level allocator, so add back as hugetlb surplus page. - * add_hugetlb_folio() removes the page from THIS list. - * Use clear_dtor to note if vmemmap was successfully allocated for - * ANY page on the list. - */ - list_for_each_entry_safe(folio, t_folio, list, lru) { - if (folio_test_hugetlb_vmemmap_optimized(folio)) { + if (!list_empty(non_hvo_folios)) { + /* + * Free any restored hugetlb pages so that restore of the + * entire list can be retried. + * The idea is that in the common case of ENOMEM errors freeing + * hugetlb pages with vmemmap we will free up memory so that we + * can allocate vmemmap for more hugetlb pages. + */ + list_for_each_entry_safe(folio, t_folio, non_hvo_folios, lru) { + list_del(&folio->lru); + spin_lock_irq(&hugetlb_lock); + __clear_hugetlb_destructor(h, folio); + spin_unlock_irq(&hugetlb_lock); + update_and_free_hugetlb_folio(h, folio, false); + cond_resched(); + } + } else { + /* + * In the case where there are no folios which can be + * immediately freed, we loop through the list trying to restore + * vmemmap individually in the hope that someone elsewhere may + * have done something to cause success (such as freeing some + * memory). If unable to restore a hugetlb page, the hugetlb + * page is made a surplus page and removed from the list. + * If are able to restore vmemmap and free one hugetlb page, we + * quit processing the list to retry the bulk operation. + */ + list_for_each_entry_safe(folio, t_folio, folio_list, lru) if (hugetlb_vmemmap_restore(h, &folio->page)) { + list_del(&folio->lru); spin_lock_irq(&hugetlb_lock); add_hugetlb_folio(h, folio, true); spin_unlock_irq(&hugetlb_lock); - } else - clear_dtor = true; - } + } else { + list_del(&folio->lru); + spin_lock_irq(&hugetlb_lock); + __clear_hugetlb_destructor(h, folio); + spin_unlock_irq(&hugetlb_lock); + update_and_free_hugetlb_folio(h, folio, false); + cond_resched(); + break; + } } +} + +static void update_and_free_pages_bulk(struct hstate *h, + struct list_head *folio_list) +{ + long ret; + struct folio *folio, *t_folio; + LIST_HEAD(non_hvo_folios); /* - * If vmemmmap allocation was performed on any folio above, take lock - * to clear destructor of all folios on list. This avoids the need to - * lock/unlock for each individual folio. - * The assumption is vmemmap allocation was performed on all or none - * of the folios on the list. This is true expect in VERY rare cases. + * First allocate required vmemmmap (if necessary) for all folios. + * Carefully handle errors and free up any available hugetlb pages + * in an effort to make forward progress. */ - if (clear_dtor) { +retry: + ret = hugetlb_vmemmap_restore_folios(h, folio_list, &non_hvo_folios); + if (ret < 0) { + bulk_vmemmap_restore_error(h, folio_list, &non_hvo_folios); + goto retry; + } + + /* + * At this point, list should be empty, ret should be >= 0 and there + * should only be pages on the non_hvo_folios list. + * Do note that the non_hvo_folios list could be empty. + * Without HVO enabled, ret will be 0 and there is no need to call + * __clear_hugetlb_destructor as this was done previously. + */ + VM_WARN_ON(!list_empty(folio_list)); + VM_WARN_ON(ret < 0); + if (!list_empty(&non_hvo_folios) && ret) { spin_lock_irq(&hugetlb_lock); - list_for_each_entry(folio, list, lru) + list_for_each_entry(folio, &non_hvo_folios, lru) __clear_hugetlb_destructor(h, folio); spin_unlock_irq(&hugetlb_lock); } - /* - * Free folios back to low level allocators. vmemmap and destructors - * were taken care of above, so update_and_free_hugetlb_folio will - * not need to take hugetlb lock. - */ - list_for_each_entry_safe(folio, t_folio, list, lru) { + list_for_each_entry_safe(folio, t_folio, &non_hvo_folios, lru) { update_and_free_hugetlb_folio(h, folio, false); cond_resched(); } diff --git a/mm/hugetlb_vmemmap.c b/mm/hugetlb_vmemmap.c index 4558b814ffab..77f44b81ff01 100644 --- a/mm/hugetlb_vmemmap.c +++ b/mm/hugetlb_vmemmap.c @@ -480,6 +480,44 @@ int hugetlb_vmemmap_restore(const struct hstate *h, struct page *head) return ret; } +/** + * hugetlb_vmemmap_restore_folios - restore vmemmap for every folio on the list. + * @h: hstate. + * @folio_list: list of folios. + * @non_hvo_folios: Output list of folios for which vmemmap exists. + * + * Return: number of folios for which vmemmap was restored, or an error code + * if an error was encountered restoring vmemmap for a folio. + * Folios that have vmemmap are moved to the non_hvo_folios + * list. Processing of entries stops when the first error is + * encountered. The folio that experienced the error and all + * non-processed folios will remain on folio_list. + */ +long hugetlb_vmemmap_restore_folios(const struct hstate *h, + struct list_head *folio_list, + struct list_head *non_hvo_folios) +{ + struct folio *folio, *t_folio; + long restored = 0; + long ret = 0; + + list_for_each_entry_safe(folio, t_folio, folio_list, lru) { + if (folio_test_hugetlb_vmemmap_optimized(folio)) { + ret = hugetlb_vmemmap_restore(h, &folio->page); + if (ret) + break; + restored++; + } + + /* Add non-optimized folios to output list */ + list_move(&folio->lru, non_hvo_folios); + } + + if (!ret) + ret = restored; + return ret; +} + /* Return true iff a HugeTLB whose vmemmap should and can be optimized. */ static bool vmemmap_should_optimize(const struct hstate *h, const struct page *head) { diff --git a/mm/hugetlb_vmemmap.h b/mm/hugetlb_vmemmap.h index c512e388dbb4..a0dcf49f46ba 100644 --- a/mm/hugetlb_vmemmap.h +++ b/mm/hugetlb_vmemmap.h @@ -19,6 +19,9 @@ #ifdef CONFIG_HUGETLB_PAGE_OPTIMIZE_VMEMMAP int hugetlb_vmemmap_restore(const struct hstate *h, struct page *head); +long hugetlb_vmemmap_restore_folios(const struct hstate *h, + struct list_head *folio_list, + struct list_head *non_hvo_folios); void hugetlb_vmemmap_optimize(const struct hstate *h, struct page *head); void hugetlb_vmemmap_optimize_folios(struct hstate *h, struct list_head *folio_list); @@ -45,6 +48,14 @@ static inline int hugetlb_vmemmap_restore(const struct hstate *h, struct page *h return 0; } +static long hugetlb_vmemmap_restore_folios(const struct hstate *h, + struct list_head *folio_list, + struct list_head *non_hvo_folios) +{ + list_splice_init(folio_list, non_hvo_folios); + return 0; +} + static inline void hugetlb_vmemmap_optimize(const struct hstate *h, struct page *head) { } -- cgit v1.2.3-70-g09d2