Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752344AbbFCBt1 (ORCPT ); Tue, 2 Jun 2015 21:49:27 -0400 Received: from mail-la0-f42.google.com ([209.85.215.42]:33135 "EHLO mail-la0-f42.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751708AbbFCBtX (ORCPT ); Tue, 2 Jun 2015 21:49:23 -0400 MIME-Version: 1.0 In-Reply-To: <1433230065-3573-3-git-send-email-gioh.kim@lge.com> References: <1433230065-3573-1-git-send-email-gioh.kim@lge.com> <1433230065-3573-3-git-send-email-gioh.kim@lge.com> Date: Wed, 3 Jun 2015 04:49:21 +0300 Message-ID: Subject: Re: [RFC 2/4] mm/balloon: apply driver page migratable into balloon driver From: Konstantin Khlebnikov To: Gioh Kim Cc: jlayton@poochiereds.net, bfields@fieldses.org, Andrew Morton , Vlastimil Babka , Joonsoo Kim , "Michael S. Tsirkin" , "Kirill A. Shutemov" , Minchan Kim , Mel Gorman , Linux Kernel Mailing List , "linux-mm@kvack.org" , virtualization@lists.linux-foundation.org, gunho.lee@lge.com Content-Type: text/plain; charset=UTF-8 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 12722 Lines: 334 On Tue, Jun 2, 2015 at 10:27 AM, Gioh Kim wrote: > Apply driver page migration into balloon driver. > > Signed-off-by: Gioh Kim > --- > drivers/virtio/virtio_balloon.c | 2 ++ > fs/proc/page.c | 4 +-- > include/linux/balloon_compaction.h | 42 ++++++++++++++++------- > include/linux/mm.h | 19 ----------- > include/uapi/linux/kernel-page-flags.h | 2 +- > mm/balloon_compaction.c | 61 ++++++++++++++++++++++++++++++++-- > 6 files changed, 94 insertions(+), 36 deletions(-) > > diff --git a/drivers/virtio/virtio_balloon.c b/drivers/virtio/virtio_balloon.c > index 6a356e3..cdd0038 100644 > --- a/drivers/virtio/virtio_balloon.c > +++ b/drivers/virtio/virtio_balloon.c > @@ -496,6 +496,8 @@ static int virtballoon_probe(struct virtio_device *vdev) > balloon_devinfo_init(&vb->vb_dev_info); > #ifdef CONFIG_BALLOON_COMPACTION > vb->vb_dev_info.migratepage = virtballoon_migratepage; > + vb->vb_dev_info.mapping = balloon_mapping_alloc(&vb->vb_dev_info, > + &balloon_aops); > #endif > > err = init_vqs(vb); > diff --git a/fs/proc/page.c b/fs/proc/page.c > index 7eee2d8..e741307 100644 > --- a/fs/proc/page.c > +++ b/fs/proc/page.c > @@ -143,8 +143,8 @@ u64 stable_page_flags(struct page *page) > if (PageBuddy(page)) > u |= 1 << KPF_BUDDY; > > - if (PageBalloon(page)) > - u |= 1 << KPF_BALLOON; > + if (PageMigratable(page)) > + u |= 1 << KPF_MIGRATABLE; > > u |= kpf_copy_bit(k, KPF_LOCKED, PG_locked); > > diff --git a/include/linux/balloon_compaction.h b/include/linux/balloon_compaction.h > index 9b0a15d..0989e96 100644 > --- a/include/linux/balloon_compaction.h > +++ b/include/linux/balloon_compaction.h > @@ -48,6 +48,7 @@ > #include > #include > #include > +#include > > /* > * Balloon device information descriptor. > @@ -62,6 +63,7 @@ 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; > }; > > extern struct page *balloon_page_enqueue(struct balloon_dev_info *b_dev_info); > @@ -73,24 +75,37 @@ static inline void balloon_devinfo_init(struct balloon_dev_info *balloon) > spin_lock_init(&balloon->pages_lock); > INIT_LIST_HEAD(&balloon->pages); > balloon->migratepage = NULL; > + balloon->mapping = NULL; > } > > #ifdef CONFIG_BALLOON_COMPACTION > -extern bool balloon_page_isolate(struct page *page); > +extern const struct address_space_operations balloon_aops; > +extern bool balloon_page_isolate(struct page *page, > + isolate_mode_t mode); > extern void balloon_page_putback(struct page *page); > -extern int balloon_page_migrate(struct page *newpage, > +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 > + * __is_movable_balloon_page - helper to perform @page PageMigratable tests > */ > static inline bool __is_movable_balloon_page(struct page *page) > { > - return PageBalloon(page); > + return PageMigratable(page); > } > > /* > - * balloon_page_movable - test PageBalloon to identify balloon pages > + * balloon_page_movable - test PageMigratable to identify balloon pages > * and PagePrivate to check that the page is not > * isolated and can be moved by compaction/migration. > * > @@ -99,7 +114,7 @@ static inline bool __is_movable_balloon_page(struct page *page) > */ > static inline bool balloon_page_movable(struct page *page) > { > - return PageBalloon(page) && PagePrivate(page); > + return PageMigratable(page) && PagePrivate(page); > } > > /* > @@ -108,7 +123,7 @@ static inline bool balloon_page_movable(struct page *page) > */ > static inline bool isolated_balloon_page(struct page *page) > { > - return PageBalloon(page); > + return PageMigratable(page); > } > > /* > @@ -123,7 +138,8 @@ static inline bool isolated_balloon_page(struct page *page) > static inline void balloon_page_insert(struct balloon_dev_info *balloon, > struct page *page) > { > - __SetPageBalloon(page); > + page->mapping = balloon->mapping; > + __SetPageMigratable(page); > SetPagePrivate(page); > set_page_private(page, (unsigned long)balloon); > list_add(&page->lru, &balloon->pages); > @@ -139,7 +155,8 @@ static inline void balloon_page_insert(struct balloon_dev_info *balloon, > */ > static inline void balloon_page_delete(struct page *page) > { > - __ClearPageBalloon(page); > + page->mapping = NULL; > + __ClearPageMigratable(page); > set_page_private(page, 0); > if (PagePrivate(page)) { > ClearPagePrivate(page); > @@ -166,13 +183,13 @@ static inline gfp_t balloon_mapping_gfp_mask(void) > static inline void balloon_page_insert(struct balloon_dev_info *balloon, > struct page *page) > { > - __SetPageBalloon(page); > + __SetPageMigratable(page); > list_add(&page->lru, &balloon->pages); > } > > static inline void balloon_page_delete(struct page *page) > { > - __ClearPageBalloon(page); > + __ClearPageMigratable(page); > list_del(&page->lru); > } > > @@ -191,7 +208,8 @@ static inline bool isolated_balloon_page(struct page *page) > return false; > } > > -static inline bool balloon_page_isolate(struct page *page) > +static inline bool balloon_page_isolate(struct page *page, > + isolate_mode_t mode) > { > return false; > } > diff --git a/include/linux/mm.h b/include/linux/mm.h > index 422c484..2d991a0 100644 > --- a/include/linux/mm.h > +++ b/include/linux/mm.h > @@ -599,25 +599,6 @@ static inline void __ClearPageBuddy(struct page *page) > atomic_set(&page->_mapcount, -1); > } > > -#define PAGE_BALLOON_MAPCOUNT_VALUE (-256) > - > -static inline int PageBalloon(struct page *page) > -{ > - return atomic_read(&page->_mapcount) == PAGE_BALLOON_MAPCOUNT_VALUE; > -} > - > -static inline void __SetPageBalloon(struct page *page) > -{ > - VM_BUG_ON_PAGE(atomic_read(&page->_mapcount) != -1, page); > - atomic_set(&page->_mapcount, PAGE_BALLOON_MAPCOUNT_VALUE); > -} > - > -static inline void __ClearPageBalloon(struct page *page) > -{ > - VM_BUG_ON_PAGE(!PageBalloon(page), page); > - atomic_set(&page->_mapcount, -1); > -} > - Why you're killing this? This mark is exported into userspace. > #define PAGE_MIGRATABLE_MAPCOUNT_VALUE (-256) > > static inline int PageMigratable(struct page *page) > diff --git a/include/uapi/linux/kernel-page-flags.h b/include/uapi/linux/kernel-page-flags.h > index a6c4962..a6a3c4b 100644 > --- a/include/uapi/linux/kernel-page-flags.h > +++ b/include/uapi/linux/kernel-page-flags.h > @@ -31,7 +31,7 @@ > > #define KPF_KSM 21 > #define KPF_THP 22 > -#define KPF_BALLOON 23 > +#define KPF_MIGRATABLE 23 > #define KPF_ZERO_PAGE 24 > > > diff --git a/mm/balloon_compaction.c b/mm/balloon_compaction.c > index fcad832..f98a500 100644 > --- a/mm/balloon_compaction.c > +++ b/mm/balloon_compaction.c > @@ -131,7 +131,7 @@ static inline void __putback_balloon_page(struct page *page) > } > > /* __isolate_lru_page() counterpart for a ballooned page */ > -bool balloon_page_isolate(struct page *page) > +bool balloon_page_isolate(struct page *page, isolate_mode_t mode) > { > /* > * Avoid burning cycles with pages that are yet under __free_pages(), > @@ -175,6 +175,9 @@ bool balloon_page_isolate(struct page *page) > /* putback_lru_page() counterpart for a ballooned page */ > void balloon_page_putback(struct page *page) > { > + if (!isolated_balloon_page(page)) > + return; > + > /* > * 'lock_page()' stabilizes the page and prevents races against > * concurrent isolation threads attempting to re-isolate it. > @@ -193,12 +196,16 @@ void balloon_page_putback(struct page *page) > } > > /* 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, > 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 rc; > + > /* > * Block others from accessing the 'newpage' when we get around to > * establishing additional references. We should be the only one > @@ -218,4 +225,54 @@ 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); > + > +struct address_space *balloon_mapping_alloc(struct balloon_dev_info *b_dev_info, > + const struct address_space_operations *a_ops) > +{ > + struct address_space *mapping; > + > + mapping = kmalloc(sizeof(*mapping), GFP_KERNEL); > + if (!mapping) > + return ERR_PTR(-ENOMEM); > + > + /* > + * Give a clean 'zeroed' status to all elements of this special > + * balloon page->mapping struct address_space instance. > + */ > + address_space_init_once(mapping); > + > + /* > + * Set mapping->flags appropriately, to allow balloon pages > + * ->mapping identification. > + */ > + mapping_set_migratable(mapping); > + mapping_set_gfp_mask(mapping, balloon_mapping_gfp_mask()); > + > + /* balloon's page->mapping->a_ops callback descriptor */ > + mapping->a_ops = a_ops; > + > + /* > + * Establish a pointer reference back to the balloon device descriptor > + * this particular page->mapping will be servicing. > + * This is used by compaction / migration procedures to identify and > + * access the balloon device pageset while isolating / migrating pages. > + * > + * As some balloon drivers can register multiple balloon devices > + * for a single guest, this also helps compaction / migration to > + * properly deal with multiple balloon pagesets, when required. > + */ > + mapping->private_data = b_dev_info; > + b_dev_info->mapping = mapping; > + > + return mapping; > +} > +EXPORT_SYMBOL_GPL(balloon_mapping_alloc); So, you're reverting my changes and return this mess. I don't mind -- zram/balloon might have special mapping but at least please create it in appropriate way: together with valid inode and superblock. I think it's ok to use anon-inodes (fs/anon_inodes.c) for that. For now anon_inodefs has only one inode and I see no reason why it cannot keep more. Probably aio/drm could use it too instead of mounting it's own presudo filesystem. > #endif /* CONFIG_BALLOON_COMPACTION */ > -- > 1.9.1 > > -- > To unsubscribe, send a message with 'unsubscribe linux-mm' in > the body to majordomo@kvack.org. For more info on Linux MM, > see: http://www.linux-mm.org/ . > Don't email: email@kvack.org -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/