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Message-ID: <556E889D.9040400@lge.com>
Date: Wed, 03 Jun 2015 13:54:53 +0900
From: Gioh Kim <gioh.kim@....com>
To: Konstantin Khlebnikov <koct9i@...il.com>
CC: jlayton@...chiereds.net, bfields@...ldses.org,
Andrew Morton <akpm@...ux-foundation.org>,
Vlastimil Babka <vbabka@...e.cz>,
Joonsoo Kim <iamjoonsoo.kim@....com>,
"Michael S. Tsirkin" <mst@...hat.com>,
"Kirill A. Shutemov" <kirill@...temov.name>,
Minchan Kim <minchan@...nel.org>, Mel Gorman <mgorman@...e.de>,
Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
"linux-mm@...ck.org" <linux-mm@...ck.org>,
virtualization@...ts.linux-foundation.org, gunho.lee@....com
Subject: Re: [RFC 2/4] mm/balloon: apply driver page migratable into balloon
driver
> On Tue, Jun 2, 2015 at 10:27 AM, Gioh Kim <gioh.kim@....com> wrote:
>> Apply driver page migration into balloon driver.
>>
>> Signed-off-by: Gioh Kim <gioh.kim@....com>
>> ---
>> 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 <linux/migrate.h>
>> #include <linux/gfp.h>
>> #include <linux/err.h>
>> +#include <linux/fs.h>
>>
>> /*
>> * 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 not bad.
Anyway my point is that the generic callbacks are need to migrate non-LRU pages
as described in patch 1/4.
The patch 2~4 are an example to show howto use the generic callbacks.
>
> 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.
Thank you for your feedback.
>
>> #endif /* CONFIG_BALLOON_COMPACTION */
>> --
>> 1.9.1
>>
>> --
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>
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