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charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit X-Rspamd-Server: rspam02 X-Rspamd-Queue-Id: 127F240004 X-Stat-Signature: wd1cscjjdzip4fh4nwiqc661mwxac9sx X-Rspam-User: X-HE-Tag: 1751373674-542350 X-HE-Meta: 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 jiVwq8S5 fKs97p/mHfD8+8Z3Zk0A6kmQkXnoWplCYk3PrzKtki8cRXH+jNAeOg0cLrJ/aCQJTdNEhPiaqiKsW6FsH0ZxrSvg4gf6uV4JffO1NPW8yyDW3xbv0AlWLwTyPq/X2FtXROYst1MtbTyYmG1ou1DDLw2OnnCT4xhEfJ1wDx40wnn3R5774Dw5n2cLZr3l5g3ifwGxZUdc9veNrC+fHKqdAeRX9QmrjXehqb+YKaQS1Y1qKX7qNaH1udSGQHHSJQuq3m7vKkg18M/EQP9gm3ycMNSnxG+hm4YKXDHKbwvNDiWcH/Q8lb7t7APGq62cAKX348j3QhXI8XiSlrSVU5pRidU2IWlefkIeZK+RH04sDdvJiPlJfQJeaGKcsX5KUHv9hPS3aFYXxJ/BE94SYrHWcRdplfJXIleRYUugFEfvNQBLCXZHAqn2X/MIyHxk/ybw7pL2tIrJQBRh6Zp1eBIWs8DRSCGocv/u948ps2FohNcudF2AUPKVdO0Kj6ha/OA0ag7Xyx708KEsF6drt70lPbPIXnroaxuzAozOw0hrmnJCFjfhylgxi5KVOqmMtin7fBVi2u6/y8s0II+tEWxBrMx0jAooo8dEUwV110UiZ5oBC1ts0J9Gc59zS6jynsQmLcQG99iMD8GLAHdGh0KdrocSVYQ== X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On 01.07.25 14:12, Lorenzo Stoakes wrote: > 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 >> Signed-off-by: David Hildenbrand > > See comment below, this feels iffy in the long run but ok as an interim measure. > > So: > > Reviewed-by: Lorenzo Stoakes > >> --- >> 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 >> #include >> #include >> +#include >> +#include >> >> #include >> >> @@ -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? Yes. The page must be marked as having movable_ops by the user. The next patch reworks that as well. A PageOffline page without movable_ops will never end up here (page_has_movable_ops() == false). > >> +#endif /* CONFIG_BALLOON_COMPACTION */ >> +#if defined(CONFIG_ZSMALLOC) && defined(CONFIG_COMPACTION) >> + if (PageZsmalloc(page)) > > And same question only for ZS malloc. Same thing. > >> + 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. Yeah, not sure yet how to clean that up in the future. As I stated somewhere, maybe we just want a registration interface to handle a specific page type. But for handling the two known in-tree users, this should get us going. Thanks! -- Cheers, David / dhildenb