| Message ID | 20230925003953.142620-5-mike.kravetz@oracle.com (mailing list archive) |
|---|---|
| State | New |
| Headers | show |
| Series | Batch hugetlb vmemmap modification operations | expand |
On 2023/9/25 08:39, Mike Kravetz wrote: > 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. > > Signed-off-by: Mike Kravetz <mike.kravetz@oracle.com> > --- > mm/hugetlb.c | 98 +++++++++++++++++++++++++++++++------------- > mm/hugetlb_vmemmap.c | 38 +++++++++++++++++ > mm/hugetlb_vmemmap.h | 10 +++++ > 3 files changed, 118 insertions(+), 28 deletions(-) > > diff --git a/mm/hugetlb.c b/mm/hugetlb.c > index da0ebd370b5f..53df35fbc3f2 100644 > --- a/mm/hugetlb.c > +++ b/mm/hugetlb.c > @@ -1834,50 +1834,92 @@ 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)) { IIUC, the folio should be deleted from the folio list since this huge page will be added to the free list (the list is corrupted), right? > 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..0b7710f90e38 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 +48,13 @@ 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) > +{ > + return 0; > +} > + > static inline void hugetlb_vmemmap_optimize(const struct hstate *h, struct page *head) > { > }
On 09/25/23 21:54, Muchun Song wrote: > > > On 2023/9/25 08:39, Mike Kravetz wrote: > > 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. > > > > Signed-off-by: Mike Kravetz <mike.kravetz@oracle.com> > > --- > > mm/hugetlb.c | 98 +++++++++++++++++++++++++++++++------------- > > mm/hugetlb_vmemmap.c | 38 +++++++++++++++++ > > mm/hugetlb_vmemmap.h | 10 +++++ > > 3 files changed, 118 insertions(+), 28 deletions(-) > > > > diff --git a/mm/hugetlb.c b/mm/hugetlb.c > > index da0ebd370b5f..53df35fbc3f2 100644 > > --- a/mm/hugetlb.c > > +++ b/mm/hugetlb.c > > @@ -1834,50 +1834,92 @@ 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)) { > > IIUC, the folio should be deleted from the folio list since this > huge page will be added to the free list (the list is corrupted), > right? Good catch! Yes, we should remove from the list here. I did exercise this specific code path and there was no list corruption. In any case, I will add the list_del(). Thank you!
On 09/25/23 10:12, Mike Kravetz wrote: > On 09/25/23 21:54, Muchun Song wrote: > > > > > > On 2023/9/25 08:39, Mike Kravetz wrote: > > > 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. > > > > > > Signed-off-by: Mike Kravetz <mike.kravetz@oracle.com> > > > --- > > > mm/hugetlb.c | 98 +++++++++++++++++++++++++++++++------------- > > > mm/hugetlb_vmemmap.c | 38 +++++++++++++++++ > > > mm/hugetlb_vmemmap.h | 10 +++++ > > > 3 files changed, 118 insertions(+), 28 deletions(-) > > > > > > diff --git a/mm/hugetlb.c b/mm/hugetlb.c > > > index da0ebd370b5f..53df35fbc3f2 100644 > > > --- a/mm/hugetlb.c > > > +++ b/mm/hugetlb.c > > > @@ -1834,50 +1834,92 @@ 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)) { > > > > IIUC, the folio should be deleted from the folio list since this > > huge page will be added to the free list (the list is corrupted), > > right? > > Good catch! Yes, we should remove from the list here. > > I did exercise this specific code path and there was no list corruption. In > any case, I will add the list_del(). Correction. My testing with simulated errors took the else branch here.
diff --git a/mm/hugetlb.c b/mm/hugetlb.c index da0ebd370b5f..53df35fbc3f2 100644 --- a/mm/hugetlb.c +++ b/mm/hugetlb.c @@ -1834,50 +1834,92 @@ 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)) { 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..0b7710f90e38 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 +48,13 @@ 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) +{ + return 0; +} + static inline void hugetlb_vmemmap_optimize(const struct hstate *h, struct page *head) { }
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. Signed-off-by: Mike Kravetz <mike.kravetz@oracle.com> --- mm/hugetlb.c | 98 +++++++++++++++++++++++++++++++------------- mm/hugetlb_vmemmap.c | 38 +++++++++++++++++ mm/hugetlb_vmemmap.h | 10 +++++ 3 files changed, 118 insertions(+), 28 deletions(-)