On Mon, Jun 30, 2025 at 03:00:00PM +0200, David Hildenbrand wrote: > ... instead, look them up statically based on the page type. Maybe in the > future we want a registration interface? At least for now, it can be > easily handled using the two page types that actually support page > migration. > > The remaining usage of page->mapping is to flag such pages as actually > being movable (having movable_ops), which we will change next. > > Reviewed-by: Zi Yan <z...@nvidia.com> > Signed-off-by: David Hildenbrand <da...@redhat.com>
See comment below, this feels iffy in the long run but ok as an interim measure. So: Reviewed-by: Lorenzo Stoakes <lorenzo.stoa...@oracle.com> > --- > include/linux/balloon_compaction.h | 2 +- > include/linux/migrate.h | 14 ++------------ > include/linux/zsmalloc.h | 2 ++ > mm/balloon_compaction.c | 1 - > mm/compaction.c | 5 ++--- > mm/migrate.c | 23 +++++++++++++++++++++++ > mm/zpdesc.h | 5 ++--- > mm/zsmalloc.c | 8 +++----- > 8 files changed, 35 insertions(+), 25 deletions(-) > > diff --git a/include/linux/balloon_compaction.h > b/include/linux/balloon_compaction.h > index 9bce8e9f5018c..a8a1706cc56f3 100644 > --- a/include/linux/balloon_compaction.h > +++ b/include/linux/balloon_compaction.h > @@ -92,7 +92,7 @@ static inline void balloon_page_insert(struct > balloon_dev_info *balloon, > struct page *page) > { > __SetPageOffline(page); > - __SetPageMovable(page, &balloon_mops); > + __SetPageMovable(page); > set_page_private(page, (unsigned long)balloon); > list_add(&page->lru, &balloon->pages); > } > diff --git a/include/linux/migrate.h b/include/linux/migrate.h > index e04035f70e36f..6aece3f3c8be8 100644 > --- a/include/linux/migrate.h > +++ b/include/linux/migrate.h > @@ -104,23 +104,13 @@ static inline int migrate_huge_page_move_mapping(struct > address_space *mapping, > #endif /* CONFIG_MIGRATION */ > > #ifdef CONFIG_COMPACTION > -void __SetPageMovable(struct page *page, const struct movable_operations > *ops); > +void __SetPageMovable(struct page *page); > #else > -static inline void __SetPageMovable(struct page *page, > - const struct movable_operations *ops) > +static inline void __SetPageMovable(struct page *page) > { > } > #endif > > -static inline > -const struct movable_operations *page_movable_ops(struct page *page) > -{ > - VM_WARN_ON_ONCE_PAGE(!page_has_movable_ops(page), page); > - > - return (const struct movable_operations *) > - ((unsigned long)page->mapping - PAGE_MAPPING_MOVABLE); > -} > - > #ifdef CONFIG_NUMA_BALANCING > int migrate_misplaced_folio_prepare(struct folio *folio, > struct vm_area_struct *vma, int node); > diff --git a/include/linux/zsmalloc.h b/include/linux/zsmalloc.h > index 13e9cc5490f71..f3ccff2d966cd 100644 > --- a/include/linux/zsmalloc.h > +++ b/include/linux/zsmalloc.h > @@ -46,4 +46,6 @@ void zs_obj_read_end(struct zs_pool *pool, unsigned long > handle, > void zs_obj_write(struct zs_pool *pool, unsigned long handle, > void *handle_mem, size_t mem_len); > > +extern const struct movable_operations zsmalloc_mops; > + > #endif > diff --git a/mm/balloon_compaction.c b/mm/balloon_compaction.c > index e4f1a122d786b..2a4a649805c11 100644 > --- a/mm/balloon_compaction.c > +++ b/mm/balloon_compaction.c > @@ -253,6 +253,5 @@ const struct movable_operations balloon_mops = { > .isolate_page = balloon_page_isolate, > .putback_page = balloon_page_putback, > }; > -EXPORT_SYMBOL_GPL(balloon_mops); > > #endif /* CONFIG_BALLOON_COMPACTION */ > diff --git a/mm/compaction.c b/mm/compaction.c > index 41fd6a1fe9a33..348eb754cb227 100644 > --- a/mm/compaction.c > +++ b/mm/compaction.c > @@ -114,11 +114,10 @@ static unsigned long release_free_list(struct list_head > *freepages) > } > > #ifdef CONFIG_COMPACTION > -void __SetPageMovable(struct page *page, const struct movable_operations > *mops) > +void __SetPageMovable(struct page *page) > { > VM_BUG_ON_PAGE(!PageLocked(page), page); > - VM_BUG_ON_PAGE((unsigned long)mops & PAGE_MAPPING_MOVABLE, page); > - page->mapping = (void *)((unsigned long)mops | PAGE_MAPPING_MOVABLE); > + page->mapping = (void *)(PAGE_MAPPING_MOVABLE); > } > EXPORT_SYMBOL(__SetPageMovable); > > diff --git a/mm/migrate.c b/mm/migrate.c > index 15d3c1031530c..c6c9998014ec8 100644 > --- a/mm/migrate.c > +++ b/mm/migrate.c > @@ -43,6 +43,8 @@ > #include <linux/sched/sysctl.h> > #include <linux/memory-tiers.h> > #include <linux/pagewalk.h> > +#include <linux/balloon_compaction.h> > +#include <linux/zsmalloc.h> > > #include <asm/tlbflush.h> > > @@ -51,6 +53,27 @@ > #include "internal.h" > #include "swap.h" > > +static const struct movable_operations *page_movable_ops(struct page *page) > +{ > + VM_WARN_ON_ONCE_PAGE(!page_has_movable_ops(page), page); > + > + /* > + * If we enable page migration for a page of a certain type by marking > + * it as movable, the page type must be sticky until the page gets freed > + * back to the buddy. > + */ Ah now this makes more sense... > +#ifdef CONFIG_BALLOON_COMPACTION > + if (PageOffline(page)) > + /* Only balloon compaction sets PageOffline pages movable. */ > + return &balloon_mops; So it's certain that if we try to invoke movable ops, and it's the balloon compaction case, the page will be offline? > +#endif /* CONFIG_BALLOON_COMPACTION */ > +#if defined(CONFIG_ZSMALLOC) && defined(CONFIG_COMPACTION) > + if (PageZsmalloc(page)) And same question only for ZS malloc. > + return &zsmalloc_mops; > +#endif /* defined(CONFIG_ZSMALLOC) && defined(CONFIG_COMPACTION) */ > + return NULL; > +} This is kind of sketchy as it's baking in assumptions implicitly, so I hope we can find an improved way of doing this later, even if it's about providing e.g. is_ballon_movable_ops_page() and is_zsmalloc_movable_ops_page() predicates that abstract this code + placing them in the relevant code so it's at least obvious to people working on this stuff that this needs to be considered. But ok as a means of getting away from having to have the hook object encoded. > + > /** > * isolate_movable_ops_page - isolate a movable_ops page for migration > * @page: The page. > diff --git a/mm/zpdesc.h b/mm/zpdesc.h > index 5763f36039736..6855d9e2732d8 100644 > --- a/mm/zpdesc.h > +++ b/mm/zpdesc.h > @@ -152,10 +152,9 @@ static inline struct zpdesc *pfn_zpdesc(unsigned long > pfn) > return page_zpdesc(pfn_to_page(pfn)); > } > > -static inline void __zpdesc_set_movable(struct zpdesc *zpdesc, > - const struct movable_operations *mops) > +static inline void __zpdesc_set_movable(struct zpdesc *zpdesc) > { > - __SetPageMovable(zpdesc_page(zpdesc), mops); > + __SetPageMovable(zpdesc_page(zpdesc)); > } > > static inline void __zpdesc_set_zsmalloc(struct zpdesc *zpdesc) > diff --git a/mm/zsmalloc.c b/mm/zsmalloc.c > index 72c2b7562c511..7192196b9421d 100644 > --- a/mm/zsmalloc.c > +++ b/mm/zsmalloc.c > @@ -1684,8 +1684,6 @@ static void lock_zspage(struct zspage *zspage) > > #ifdef CONFIG_COMPACTION > > -static const struct movable_operations zsmalloc_mops; > - > static void replace_sub_page(struct size_class *class, struct zspage *zspage, > struct zpdesc *newzpdesc, struct zpdesc > *oldzpdesc) > { > @@ -1708,7 +1706,7 @@ static void replace_sub_page(struct size_class *class, > struct zspage *zspage, > set_first_obj_offset(newzpdesc, first_obj_offset); > if (unlikely(ZsHugePage(zspage))) > newzpdesc->handle = oldzpdesc->handle; > - __zpdesc_set_movable(newzpdesc, &zsmalloc_mops); > + __zpdesc_set_movable(newzpdesc); > } > > static bool zs_page_isolate(struct page *page, isolate_mode_t mode) > @@ -1815,7 +1813,7 @@ static void zs_page_putback(struct page *page) > { > } > > -static const struct movable_operations zsmalloc_mops = { > +const struct movable_operations zsmalloc_mops = { > .isolate_page = zs_page_isolate, > .migrate_page = zs_page_migrate, > .putback_page = zs_page_putback, > @@ -1878,7 +1876,7 @@ static void SetZsPageMovable(struct zs_pool *pool, > struct zspage *zspage) > > do { > WARN_ON(!zpdesc_trylock(zpdesc)); > - __zpdesc_set_movable(zpdesc, &zsmalloc_mops); > + __zpdesc_set_movable(zpdesc); > zpdesc_unlock(zpdesc); > } while ((zpdesc = get_next_zpdesc(zpdesc)) != NULL); > } > -- > 2.49.0 >