> > I sent a patch about page allocation for less fragmentation. > http://permalink.gmane.org/gmane.linux.kernel.mm/130599 > > It proposes a page allocator allocates pages in the same pageblock > for the drivers to move their unmovable pages. Some drivers which comsumes many pages > and increases system fragmentation use the allocator to move their pages to > decrease fragmentation. > > I think I can try another approach. > There is a compaction code for balloon pages. > But the compaction code cannot migrate pages of other drivers. > If there is a generic migration framework applicable to any drivers, > drivers can register their migration functions. > And the compaction can migrate movable pages and also driver's pages. > > I'm not familiar with virtualization so I couldn't test this patch yet. A RFC, no? > But if mm developers agree with this approach, I will complete this patch. > > I would do appreciate any feedback. > > Signed-off-by: Gioh Kim <gioh.kim@xxxxxxx> > --- > drivers/virtio/virtio_balloon.c | 2 ++ > include/linux/balloon_compaction.h | 23 +++++++++--- > include/linux/fs.h | 3 ++ > include/linux/pagemap.h | 26 ++++++++++++++ > mm/balloon_compaction.c | 68 ++++++++++++++++++++++++++++++++++-- > mm/compaction.c | 7 ++-- > mm/migrate.c | 24 ++++++------- > 7 files changed, 129 insertions(+), 24 deletions(-) > > diff --git a/drivers/virtio/virtio_balloon.c b/drivers/virtio/virtio_balloon.c > index 0413157..cd9b8e4 100644 > --- a/drivers/virtio/virtio_balloon.c > +++ b/drivers/virtio/virtio_balloon.c > @@ -486,6 +486,8 @@ static int virtballoon_probe(struct virtio_device *vdev) > > balloon_devinfo_init(&vb->vb_dev_info); > #ifdef CONFIG_BALLOON_COMPACTION > + vb->vb_dev_info.mapping = balloon_mapping_alloc(&vb->vb_dev_info, > + &balloon_aops); > vb->vb_dev_info.migratepage = virtballoon_migratepage; > #endif > > diff --git a/include/linux/balloon_compaction.h b/include/linux/balloon_compaction.h > index 9b0a15d..0af32b3 100644 > --- a/include/linux/balloon_compaction.h > +++ b/include/linux/balloon_compaction.h > @@ -62,6 +62,7 @@ struct balloon_dev_info { > struct list_head pages; /* Pages enqueued & handled to Host */ > int (*migratepage)(struct balloon_dev_info *, struct page *newpage, > struct page *page, enum migrate_mode mode); > + struct address_space *mapping; Better if a comment line is added. > }; > > extern struct page *balloon_page_enqueue(struct balloon_dev_info *b_dev_info); > @@ -76,10 +77,22 @@ static inline void balloon_devinfo_init(struct balloon_dev_info *balloon) > } > > #ifdef CONFIG_BALLOON_COMPACTION > -extern bool balloon_page_isolate(struct page *page); > -extern void balloon_page_putback(struct page *page); > -extern int balloon_page_migrate(struct page *newpage, > - struct page *page, enum migrate_mode mode); > +extern const struct address_space_operations balloon_aops; > +extern int balloon_page_isolate(struct page *page); > +extern int balloon_page_putback(struct page *page); > +extern int balloon_page_migrate(struct address_space *mapping, > + struct page *newpage, > + struct page *page, > + enum migrate_mode mode); > + > +extern struct address_space > +*balloon_mapping_alloc(struct balloon_dev_info *b_dev_info, > + const struct address_space_operations *a_ops); > + > +static inline void balloon_mapping_free(struct address_space *balloon_mapping) > +{ > + kfree(balloon_mapping); > +} > > /* > * __is_movable_balloon_page - helper to perform @page PageBalloon tests > @@ -123,6 +136,7 @@ static inline bool isolated_balloon_page(struct page *page) > static inline void balloon_page_insert(struct balloon_dev_info *balloon, > struct page *page) > { > + page->mapping = balloon->mapping; > __SetPageBalloon(page); > SetPagePrivate(page); > set_page_private(page, (unsigned long)balloon); > @@ -139,6 +153,7 @@ static inline void balloon_page_insert(struct balloon_dev_info *balloon, > */ > static inline void balloon_page_delete(struct page *page) > { > + page->mapping = NULL; > __ClearPageBalloon(page); > set_page_private(page, 0); > if (PagePrivate(page)) { > diff --git a/include/linux/fs.h b/include/linux/fs.h > index b4d71b5..de463b9 100644 > --- a/include/linux/fs.h > +++ b/include/linux/fs.h > @@ -368,6 +368,9 @@ struct address_space_operations { > */ > int (*migratepage) (struct address_space *, > struct page *, struct page *, enum migrate_mode); > + int (*isolatepage)(struct page *); > + int (*putbackpage)(struct page *); > + > int (*launder_page) (struct page *); > int (*is_partially_uptodate) (struct page *, unsigned long, > unsigned long); > diff --git a/include/linux/pagemap.h b/include/linux/pagemap.h > index 4b3736f..715b5b2 100644 > --- a/include/linux/pagemap.h > +++ b/include/linux/pagemap.h > @@ -25,6 +25,7 @@ enum mapping_flags { > AS_MM_ALL_LOCKS = __GFP_BITS_SHIFT + 2, /* under mm_take_all_locks() */ > AS_UNEVICTABLE = __GFP_BITS_SHIFT + 3, /* e.g., ramdisk, SHM_LOCK */ > AS_EXITING = __GFP_BITS_SHIFT + 4, /* final truncate in progress */ > + AS_MIGRATABLE = __GFP_BITS_SHIFT + 5, > }; > > static inline void mapping_set_error(struct address_space *mapping, int error) > @@ -54,6 +55,31 @@ static inline int mapping_unevictable(struct address_space *mapping) > return !!mapping; > } > > +static inline void mapping_set_migratable(struct address_space *mapping) > +{ > + set_bit(AS_MIGRATABLE, &mapping->flags); > +} > + > +static inline void mapping_clear_migratable(struct address_space *mapping) > +{ > + clear_bit(AS_MIGRATABLE, &mapping->flags); > +} > + > +static inline int __mapping_ops(struct address_space *mapping) > +{ > + return mapping->a_ops && > + mapping->a_ops->migratepage && > + mapping->a_ops->isolatepage && > + mapping->a_ops->putbackpage; > +} > + > +static inline int mapping_migratable(struct address_space *mapping) > +{ > + if (mapping && __mapping_ops(mapping)) s/__mapping_ops/__mapping_migratable/ given naming hurts brain? > + return test_bit(AS_MIGRATABLE, &mapping->flags); > + return !!mapping; > +} > + > static inline void mapping_set_exiting(struct address_space *mapping) > { > set_bit(AS_EXITING, &mapping->flags); > diff --git a/mm/balloon_compaction.c b/mm/balloon_compaction.c > index fcad832..2e9d635 100644 > --- a/mm/balloon_compaction.c > +++ b/mm/balloon_compaction.c > @@ -131,8 +131,11 @@ static inline void __putback_balloon_page(struct page *page) > } > > /* __isolate_lru_page() counterpart for a ballooned page */ > -bool balloon_page_isolate(struct page *page) > +int balloon_page_isolate(struct page *page) > { > + if (!balloon_page_movable(page)) > + return false; > + > /* > * Avoid burning cycles with pages that are yet under __free_pages(), > * or just got freed under us. > @@ -173,8 +176,11 @@ bool balloon_page_isolate(struct page *page) > } > > /* putback_lru_page() counterpart for a ballooned page */ > -void balloon_page_putback(struct page *page) > +int balloon_page_putback(struct page *page) > { > + if (!isolated_balloon_page(page)) > + return 0; > + > /* > * 'lock_page()' stabilizes the page and prevents races against > * concurrent isolation threads attempting to re-isolate it. > @@ -190,15 +196,20 @@ void balloon_page_putback(struct page *page) > dump_page(page, "not movable balloon page"); > } > unlock_page(page); > + return 0; > } > > /* move_to_new_page() counterpart for a ballooned page */ > -int balloon_page_migrate(struct page *newpage, > +int balloon_page_migrate(struct address_space *mapping, > + struct page *newpage, Looks the newly added mapping is not necessary, yes? > struct page *page, enum migrate_mode mode) > { > struct balloon_dev_info *balloon = balloon_page_device(page); > int rc = -EAGAIN; > > + if (!isolated_balloon_page(page)) > + return 0; > + > /* > * Block others from accessing the 'newpage' when we get around to > * establishing additional references. We should be the only one > @@ -218,4 +229,55 @@ int balloon_page_migrate(struct page *newpage, > unlock_page(newpage); > return rc; > } > + > +/* define the balloon_mapping->a_ops callback to allow balloon page migration */ > +const struct address_space_operations balloon_aops = { > + .migratepage = balloon_page_migrate, > + .isolatepage = balloon_page_isolate, > + .putbackpage = balloon_page_putback, > +}; > +EXPORT_SYMBOL_GPL(balloon_aops); -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxx. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>