Re: [PATCH v7 11/12] zsmalloc: page migration support

[Minchan Kim <minchan@kernel.org>]

Hello Chulmin,

On Wed, Jan 18, 2017 at 07:13:21PM -0500, Chulmin Kim wrote:
> Hello. Minchan, and all zsmalloc guys.
> 
> I have a quick question.
> Is zsmalloc considering memory barrier things correctly?
> 
> AFAIK, in ARM64,
> zsmalloc relies on dmb operation in bit_spin_unlock only.
> (It seems that dmb operations in spinlock functions are being prepared,
> but let is be aside as it is not merged yet.)
> 
> If I am correct,
> migrating a page in a zspage filled with free objs
> may cause the corruption cause bit_spin_unlock will not be executed at all.
> 
> I am not sure this is enough memory barrier for zsmalloc operations.
> 
> Can you enlighten me?

Do you mean bit_spin_unlock is broken or zsmalloc locking scheme broken?
Could you please describe what you are concerning in detail?
It would be very helpful if you say it with a example!

Thanks.

> 
> 
> THanks!
> CHulmin KIm
> 
> 
> 
> On 05/31/2016 07:21 PM, Minchan Kim wrote:
> >This patch introduces run-time migration feature for zspage.
> >
> >For migration, VM uses page.lru field so it would be better to not use
> >page.next field which is unified with page.lru for own purpose.
> >For that, firstly, we can get first object offset of the page via
> >runtime calculation instead of using page.index so we can use
> >page.index as link for page chaining instead of page.next.
> >	
> >In case of huge object, it stores handle to page.index instead of
> >next link of page chaining because huge object doesn't need to next
> >link for page chaining. So get_next_page need to identify huge
> >object to return NULL. For it, this patch uses PG_owner_priv_1 flag
> >of the page flag.
> >
> >For migration, it supports three functions
> >
> >* zs_page_isolate
> >
> >It isolates a zspage which includes a subpage VM want to migrate
> >from class so anyone cannot allocate new object from the zspage.
> >
> >We could try to isolate a zspage by the number of subpage so
> >subsequent isolation trial of other subpage of the zpsage shouldn't
> >fail. For that, we introduce zspage.isolated count. With that,
> >zs_page_isolate can know whether zspage is already isolated or not
> >for migration so if it is isolated for migration, subsequent
> >isolation trial can be successful without trying further isolation.
> >
> >* zs_page_migrate
> >
> >First of all, it holds write-side zspage->lock to prevent migrate other
> >subpage in zspage. Then, lock all objects in the page VM want to migrate.
> >The reason we should lock all objects in the page is due to race between
> >zs_map_object and zs_page_migrate.
> >
> >zs_map_object				zs_page_migrate
> >
> >pin_tag(handle)
> >obj = handle_to_obj(handle)
> >obj_to_location(obj, &page, &obj_idx);
> >
> >					write_lock(&zspage->lock)
> >					if (!trypin_tag(handle))
> >						goto unpin_object
> >
> >zspage = get_zspage(page);
> >read_lock(&zspage->lock);
> >
> >If zs_page_migrate doesn't do trypin_tag, zs_map_object's page can
> >be stale by migration so it goes crash.
> >
> >If it locks all of objects successfully, it copies content from
> >old page to new one, finally, create new zspage chain with new page.
> >And if it's last isolated subpage in the zspage, put the zspage back
> >to class.
> >
> >* zs_page_putback
> >
> >It returns isolated zspage to right fullness_group list if it fails to
> >migrate a page. If it find a zspage is ZS_EMPTY, it queues zspage
> >freeing to workqueue. See below about async zspage freeing.
> >
> >This patch introduces asynchronous zspage free. The reason to need it
> >is we need page_lock to clear PG_movable but unfortunately,
> >zs_free path should be atomic so the apporach is try to grab page_lock.
> >If it got page_lock of all of pages successfully, it can free zspage
> >immediately. Otherwise, it queues free request and free zspage via
> >workqueue in process context.
> >
> >If zs_free finds the zspage is isolated when it try to free zspage,
> >it delays the freeing until zs_page_putback finds it so it will free
> >free the zspage finally.
> >
> >In this patch, we expand fullness_list from ZS_EMPTY to ZS_FULL.
> >First of all, it will use ZS_EMPTY list for delay freeing.
> >And with adding ZS_FULL list, it makes to identify whether zspage is
> >isolated or not via list_empty(&zspage->list) test.
> >
> >Cc: Sergey Senozhatsky <sergey.senozhatsky@gmail.com>
> >Signed-off-by: Minchan Kim <minchan@kernel.org>
> >---
> > include/uapi/linux/magic.h |   1 +
> > mm/zsmalloc.c              | 793 ++++++++++++++++++++++++++++++++++++++-------
> > 2 files changed, 672 insertions(+), 122 deletions(-)
> >
> >diff --git a/include/uapi/linux/magic.h b/include/uapi/linux/magic.h
> >index d829ce63529d..e398beac67b8 100644
> >--- a/include/uapi/linux/magic.h
> >+++ b/include/uapi/linux/magic.h
> >@@ -81,5 +81,6 @@
> > /* Since UDF 2.01 is ISO 13346 based... */
> > #define UDF_SUPER_MAGIC		0x15013346
> > #define BALLOON_KVM_MAGIC	0x13661366
> >+#define ZSMALLOC_MAGIC		0x58295829
> >
> > #endif /* __LINUX_MAGIC_H__ */
> >diff --git a/mm/zsmalloc.c b/mm/zsmalloc.c
> >index c6fb543cfb98..a80100db16d6 100644
> >--- a/mm/zsmalloc.c
> >+++ b/mm/zsmalloc.c
> >@@ -17,14 +17,14 @@
> >  *
> >  * Usage of struct page fields:
> >  *	page->private: points to zspage
> >- *	page->index: offset of the first object starting in this page.
> >- *		For the first page, this is always 0, so we use this field
> >- *		to store handle for huge object.
> >- *	page->next: links together all component pages of a zspage
> >+ *	page->freelist(index): links together all component pages of a zspage
> >+ *		For the huge page, this is always 0, so we use this field
> >+ *		to store handle.
> >  *
> >  * Usage of struct page flags:
> >  *	PG_private: identifies the first component page
> >  *	PG_private2: identifies the last component page
> >+ *	PG_owner_priv_1: indentifies the huge component page
> >  *
> >  */
> >
> >@@ -49,6 +49,11 @@
> > #include <linux/debugfs.h>
> > #include <linux/zsmalloc.h>
> > #include <linux/zpool.h>
> >+#include <linux/mount.h>
> >+#include <linux/compaction.h>
> >+#include <linux/pagemap.h>
> >+
> >+#define ZSPAGE_MAGIC	0x58
> >
> > /*
> >  * This must be power of 2 and greater than of equal to sizeof(link_free).
> >@@ -136,25 +141,23 @@
> >  * We do not maintain any list for completely empty or full pages
> >  */
> > enum fullness_group {
> >-	ZS_ALMOST_FULL,
> >-	ZS_ALMOST_EMPTY,
> > 	ZS_EMPTY,
> >-	ZS_FULL
> >+	ZS_ALMOST_EMPTY,
> >+	ZS_ALMOST_FULL,
> >+	ZS_FULL,
> >+	NR_ZS_FULLNESS,
> > };
> >
> > enum zs_stat_type {
> >+	CLASS_EMPTY,
> >+	CLASS_ALMOST_EMPTY,
> >+	CLASS_ALMOST_FULL,
> >+	CLASS_FULL,
> > 	OBJ_ALLOCATED,
> > 	OBJ_USED,
> >-	CLASS_ALMOST_FULL,
> >-	CLASS_ALMOST_EMPTY,
> >+	NR_ZS_STAT_TYPE,
> > };
> >
> >-#ifdef CONFIG_ZSMALLOC_STAT
> >-#define NR_ZS_STAT_TYPE	(CLASS_ALMOST_EMPTY + 1)
> >-#else
> >-#define NR_ZS_STAT_TYPE	(OBJ_USED + 1)
> >-#endif
> >-
> > struct zs_size_stat {
> > 	unsigned long objs[NR_ZS_STAT_TYPE];
> > };
> >@@ -163,6 +166,10 @@ struct zs_size_stat {
> > static struct dentry *zs_stat_root;
> > #endif
> >
> >+#ifdef CONFIG_COMPACTION
> >+static struct vfsmount *zsmalloc_mnt;
> >+#endif
> >+
> > /*
> >  * number of size_classes
> >  */
> >@@ -186,23 +193,36 @@ static const int fullness_threshold_frac = 4;
> >
> > struct size_class {
> > 	spinlock_t lock;
> >-	struct list_head fullness_list[2];
> >+	struct list_head fullness_list[NR_ZS_FULLNESS];
> > 	/*
> > 	 * Size of objects stored in this class. Must be multiple
> > 	 * of ZS_ALIGN.
> > 	 */
> > 	int size;
> > 	int objs_per_zspage;
> >-	unsigned int index;
> >-
> >-	struct zs_size_stat stats;
> >-
> > 	/* Number of PAGE_SIZE sized pages to combine to form a 'zspage' */
> > 	int pages_per_zspage;
> >-	/* huge object: pages_per_zspage == 1 && maxobj_per_zspage == 1 */
> >-	bool huge;
> >+
> >+	unsigned int index;
> >+	struct zs_size_stat stats;
> > };
> >
> >+/* huge object: pages_per_zspage == 1 && maxobj_per_zspage == 1 */
> >+static void SetPageHugeObject(struct page *page)
> >+{
> >+	SetPageOwnerPriv1(page);
> >+}
> >+
> >+static void ClearPageHugeObject(struct page *page)
> >+{
> >+	ClearPageOwnerPriv1(page);
> >+}
> >+
> >+static int PageHugeObject(struct page *page)
> >+{
> >+	return PageOwnerPriv1(page);
> >+}
> >+
> > /*
> >  * Placed within free objects to form a singly linked list.
> >  * For every zspage, zspage->freeobj gives head of this list.
> >@@ -244,6 +264,10 @@ struct zs_pool {
> > #ifdef CONFIG_ZSMALLOC_STAT
> > 	struct dentry *stat_dentry;
> > #endif
> >+#ifdef CONFIG_COMPACTION
> >+	struct inode *inode;
> >+	struct work_struct free_work;
> >+#endif
> > };
> >
> > /*
> >@@ -252,16 +276,23 @@ struct zs_pool {
> >  */
> > #define FULLNESS_BITS	2
> > #define CLASS_BITS	8
> >+#define ISOLATED_BITS	3
> >+#define MAGIC_VAL_BITS	8
> >
> > struct zspage {
> > 	struct {
> > 		unsigned int fullness:FULLNESS_BITS;
> > 		unsigned int class:CLASS_BITS;
> >+		unsigned int isolated:ISOLATED_BITS;
> >+		unsigned int magic:MAGIC_VAL_BITS;
> > 	};
> > 	unsigned int inuse;
> > 	unsigned int freeobj;
> > 	struct page *first_page;
> > 	struct list_head list; /* fullness list */
> >+#ifdef CONFIG_COMPACTION
> >+	rwlock_t lock;
> >+#endif
> > };
> >
> > struct mapping_area {
> >@@ -274,6 +305,28 @@ struct mapping_area {
> > 	enum zs_mapmode vm_mm; /* mapping mode */
> > };
> >
> >+#ifdef CONFIG_COMPACTION
> >+static int zs_register_migration(struct zs_pool *pool);
> >+static void zs_unregister_migration(struct zs_pool *pool);
> >+static void migrate_lock_init(struct zspage *zspage);
> >+static void migrate_read_lock(struct zspage *zspage);
> >+static void migrate_read_unlock(struct zspage *zspage);
> >+static void kick_deferred_free(struct zs_pool *pool);
> >+static void init_deferred_free(struct zs_pool *pool);
> >+static void SetZsPageMovable(struct zs_pool *pool, struct zspage *zspage);
> >+#else
> >+static int zsmalloc_mount(void) { return 0; }
> >+static void zsmalloc_unmount(void) {}
> >+static int zs_register_migration(struct zs_pool *pool) { return 0; }
> >+static void zs_unregister_migration(struct zs_pool *pool) {}
> >+static void migrate_lock_init(struct zspage *zspage) {}
> >+static void migrate_read_lock(struct zspage *zspage) {}
> >+static void migrate_read_unlock(struct zspage *zspage) {}
> >+static void kick_deferred_free(struct zs_pool *pool) {}
> >+static void init_deferred_free(struct zs_pool *pool) {}
> >+static void SetZsPageMovable(struct zs_pool *pool, struct zspage *zspage) {}
> >+#endif
> >+
> > static int create_cache(struct zs_pool *pool)
> > {
> > 	pool->handle_cachep = kmem_cache_create("zs_handle", ZS_HANDLE_SIZE,
> >@@ -301,7 +354,7 @@ static void destroy_cache(struct zs_pool *pool)
> > static unsigned long cache_alloc_handle(struct zs_pool *pool, gfp_t gfp)
> > {
> > 	return (unsigned long)kmem_cache_alloc(pool->handle_cachep,
> >-			gfp & ~__GFP_HIGHMEM);
> >+			gfp & ~(__GFP_HIGHMEM|__GFP_MOVABLE));
> > }
> >
> > static void cache_free_handle(struct zs_pool *pool, unsigned long handle)
> >@@ -311,7 +364,8 @@ static void cache_free_handle(struct zs_pool *pool, unsigned long handle)
> >
> > static struct zspage *cache_alloc_zspage(struct zs_pool *pool, gfp_t flags)
> > {
> >-	return kmem_cache_alloc(pool->zspage_cachep, flags & ~__GFP_HIGHMEM);
> >+	return kmem_cache_alloc(pool->zspage_cachep,
> >+			flags & ~(__GFP_HIGHMEM|__GFP_MOVABLE));
> > };
> >
> > static void cache_free_zspage(struct zs_pool *pool, struct zspage *zspage)
> >@@ -421,11 +475,17 @@ static unsigned int get_maxobj_per_zspage(int size, int pages_per_zspage)
> > /* per-cpu VM mapping areas for zspage accesses that cross page boundaries */
> > static DEFINE_PER_CPU(struct mapping_area, zs_map_area);
> >
> >+static bool is_zspage_isolated(struct zspage *zspage)
> >+{
> >+	return zspage->isolated;
> >+}
> >+
> > static int is_first_page(struct page *page)
> > {
> > 	return PagePrivate(page);
> > }
> >
> >+/* Protected by class->lock */
> > static inline int get_zspage_inuse(struct zspage *zspage)
> > {
> > 	return zspage->inuse;
> >@@ -441,20 +501,12 @@ static inline void mod_zspage_inuse(struct zspage *zspage, int val)
> > 	zspage->inuse += val;
> > }
> >
> >-static inline int get_first_obj_offset(struct page *page)
> >+static inline struct page *get_first_page(struct zspage *zspage)
> > {
> >-	if (is_first_page(page))
> >-		return 0;
> >+	struct page *first_page = zspage->first_page;
> >
> >-	return page->index;
> >-}
> >-
> >-static inline void set_first_obj_offset(struct page *page, int offset)
> >-{
> >-	if (is_first_page(page))
> >-		return;
> >-
> >-	page->index = offset;
> >+	VM_BUG_ON_PAGE(!is_first_page(first_page), first_page);
> >+	return first_page;
> > }
> >
> > static inline unsigned int get_freeobj(struct zspage *zspage)
> >@@ -471,6 +523,8 @@ static void get_zspage_mapping(struct zspage *zspage,
> > 				unsigned int *class_idx,
> > 				enum fullness_group *fullness)
> > {
> >+	VM_BUG_ON(zspage->magic != ZSPAGE_MAGIC);
> >+
> > 	*fullness = zspage->fullness;
> > 	*class_idx = zspage->class;
> > }
> >@@ -504,23 +558,19 @@ static int get_size_class_index(int size)
> > static inline void zs_stat_inc(struct size_class *class,
> > 				enum zs_stat_type type, unsigned long cnt)
> > {
> >-	if (type < NR_ZS_STAT_TYPE)
> >-		class->stats.objs[type] += cnt;
> >+	class->stats.objs[type] += cnt;
> > }
> >
> > static inline void zs_stat_dec(struct size_class *class,
> > 				enum zs_stat_type type, unsigned long cnt)
> > {
> >-	if (type < NR_ZS_STAT_TYPE)
> >-		class->stats.objs[type] -= cnt;
> >+	class->stats.objs[type] -= cnt;
> > }
> >
> > static inline unsigned long zs_stat_get(struct size_class *class,
> > 				enum zs_stat_type type)
> > {
> >-	if (type < NR_ZS_STAT_TYPE)
> >-		return class->stats.objs[type];
> >-	return 0;
> >+	return class->stats.objs[type];
> > }
> >
> > #ifdef CONFIG_ZSMALLOC_STAT
> >@@ -664,6 +714,7 @@ static inline void zs_pool_stat_destroy(struct zs_pool *pool)
> > }
> > #endif
> >
> >+
> > /*
> >  * For each size class, zspages are divided into different groups
> >  * depending on how "full" they are. This was done so that we could
> >@@ -704,15 +755,9 @@ static void insert_zspage(struct size_class *class,
> > {
> > 	struct zspage *head;
> >
> >-	if (fullness >= ZS_EMPTY)
> >-		return;
> >-
> >+	zs_stat_inc(class, fullness, 1);
> > 	head = list_first_entry_or_null(&class->fullness_list[fullness],
> > 					struct zspage, list);
> >-
> >-	zs_stat_inc(class, fullness == ZS_ALMOST_EMPTY ?
> >-			CLASS_ALMOST_EMPTY : CLASS_ALMOST_FULL, 1);
> >-
> > 	/*
> > 	 * We want to see more ZS_FULL pages and less almost empty/full.
> > 	 * Put pages with higher ->inuse first.
> >@@ -734,14 +779,11 @@ static void remove_zspage(struct size_class *class,
> > 				struct zspage *zspage,
> > 				enum fullness_group fullness)
> > {
> >-	if (fullness >= ZS_EMPTY)
> >-		return;
> >-
> > 	VM_BUG_ON(list_empty(&class->fullness_list[fullness]));
> >+	VM_BUG_ON(is_zspage_isolated(zspage));
> >
> > 	list_del_init(&zspage->list);
> >-	zs_stat_dec(class, fullness == ZS_ALMOST_EMPTY ?
> >-			CLASS_ALMOST_EMPTY : CLASS_ALMOST_FULL, 1);
> >+	zs_stat_dec(class, fullness, 1);
> > }
> >
> > /*
> >@@ -764,8 +806,11 @@ static enum fullness_group fix_fullness_group(struct size_class *class,
> > 	if (newfg == currfg)
> > 		goto out;
> >
> >-	remove_zspage(class, zspage, currfg);
> >-	insert_zspage(class, zspage, newfg);
> >+	if (!is_zspage_isolated(zspage)) {
> >+		remove_zspage(class, zspage, currfg);
> >+		insert_zspage(class, zspage, newfg);
> >+	}
> >+
> > 	set_zspage_mapping(zspage, class_idx, newfg);
> >
> > out:
> >@@ -808,19 +853,45 @@ static int get_pages_per_zspage(int class_size)
> > 	return max_usedpc_order;
> > }
> >
> >-static struct page *get_first_page(struct zspage *zspage)
> >+static struct zspage *get_zspage(struct page *page)
> > {
> >-	return zspage->first_page;
> >+	struct zspage *zspage = (struct zspage *)page->private;
> >+
> >+	VM_BUG_ON(zspage->magic != ZSPAGE_MAGIC);
> >+	return zspage;
> > }
> >
> >-static struct zspage *get_zspage(struct page *page)
> >+static struct page *get_next_page(struct page *page)
> > {
> >-	return (struct zspage *)page->private;
> >+	if (unlikely(PageHugeObject(page)))
> >+		return NULL;
> >+
> >+	return page->freelist;
> > }
> >
> >-static struct page *get_next_page(struct page *page)
> >+/* Get byte offset of first object in the @page */
> >+static int get_first_obj_offset(struct size_class *class,
> >+				struct page *first_page, struct page *page)
> > {
> >-	return page->next;
> >+	int pos;
> >+	int page_idx = 0;
> >+	int ofs = 0;
> >+	struct page *cursor = first_page;
> >+
> >+	if (first_page == page)
> >+		goto out;
> >+
> >+	while (page != cursor) {
> >+		page_idx++;
> >+		cursor = get_next_page(cursor);
> >+	}
> >+
> >+	pos = class->objs_per_zspage * class->size *
> >+		page_idx / class->pages_per_zspage;
> >+
> >+	ofs = (pos + class->size) % PAGE_SIZE;
> >+out:
> >+	return ofs;
> > }
> >
> > /**
> >@@ -857,16 +928,20 @@ static unsigned long handle_to_obj(unsigned long handle)
> > 	return *(unsigned long *)handle;
> > }
> >
> >-static unsigned long obj_to_head(struct size_class *class, struct page *page,
> >-			void *obj)
> >+static unsigned long obj_to_head(struct page *page, void *obj)
> > {
> >-	if (class->huge) {
> >+	if (unlikely(PageHugeObject(page))) {
> > 		VM_BUG_ON_PAGE(!is_first_page(page), page);
> > 		return page->index;
> > 	} else
> > 		return *(unsigned long *)obj;
> > }
> >
> >+static inline int testpin_tag(unsigned long handle)
> >+{
> >+	return bit_spin_is_locked(HANDLE_PIN_BIT, (unsigned long *)handle);
> >+}
> >+
> > static inline int trypin_tag(unsigned long handle)
> > {
> > 	return bit_spin_trylock(HANDLE_PIN_BIT, (unsigned long *)handle);
> >@@ -884,27 +959,93 @@ static void unpin_tag(unsigned long handle)
> >
> > static void reset_page(struct page *page)
> > {
> >+	__ClearPageMovable(page);
> > 	clear_bit(PG_private, &page->flags);
> > 	clear_bit(PG_private_2, &page->flags);
> > 	set_page_private(page, 0);
> >-	page->index = 0;
> >+	ClearPageHugeObject(page);
> >+	page->freelist = NULL;
> > }
> >
> >-static void free_zspage(struct zs_pool *pool, struct zspage *zspage)
> >+/*
> >+ * To prevent zspage destroy during migration, zspage freeing should
> >+ * hold locks of all pages in the zspage.
> >+ */
> >+void lock_zspage(struct zspage *zspage)
> >+{
> >+	struct page *page = get_first_page(zspage);
> >+
> >+	do {
> >+		lock_page(page);
> >+	} while ((page = get_next_page(page)) != NULL);
> >+}
> >+
> >+int trylock_zspage(struct zspage *zspage)
> >+{
> >+	struct page *cursor, *fail;
> >+
> >+	for (cursor = get_first_page(zspage); cursor != NULL; cursor =
> >+					get_next_page(cursor)) {
> >+		if (!trylock_page(cursor)) {
> >+			fail = cursor;
> >+			goto unlock;
> >+		}
> >+	}
> >+
> >+	return 1;
> >+unlock:
> >+	for (cursor = get_first_page(zspage); cursor != fail; cursor =
> >+					get_next_page(cursor))
> >+		unlock_page(cursor);
> >+
> >+	return 0;
> >+}
> >+
> >+static void __free_zspage(struct zs_pool *pool, struct size_class *class,
> >+				struct zspage *zspage)
> > {
> > 	struct page *page, *next;
> >+	enum fullness_group fg;
> >+	unsigned int class_idx;
> >+
> >+	get_zspage_mapping(zspage, &class_idx, &fg);
> >+
> >+	assert_spin_locked(&class->lock);
> >
> > 	VM_BUG_ON(get_zspage_inuse(zspage));
> >+	VM_BUG_ON(fg != ZS_EMPTY);
> >
> >-	next = page = zspage->first_page;
> >+	next = page = get_first_page(zspage);
> > 	do {
> >-		next = page->next;
> >+		VM_BUG_ON_PAGE(!PageLocked(page), page);
> >+		next = get_next_page(page);
> > 		reset_page(page);
> >+		unlock_page(page);
> > 		put_page(page);
> > 		page = next;
> > 	} while (page != NULL);
> >
> > 	cache_free_zspage(pool, zspage);
> >+
> >+	zs_stat_dec(class, OBJ_ALLOCATED, get_maxobj_per_zspage(
> >+			class->size, class->pages_per_zspage));
> >+	atomic_long_sub(class->pages_per_zspage,
> >+					&pool->pages_allocated);
> >+}
> >+
> >+static void free_zspage(struct zs_pool *pool, struct size_class *class,
> >+				struct zspage *zspage)
> >+{
> >+	VM_BUG_ON(get_zspage_inuse(zspage));
> >+	VM_BUG_ON(list_empty(&zspage->list));
> >+
> >+	if (!trylock_zspage(zspage)) {
> >+		kick_deferred_free(pool);
> >+		return;
> >+	}
> >+
> >+	remove_zspage(class, zspage, ZS_EMPTY);
> >+	__free_zspage(pool, class, zspage);
> > }
> >
> > /* Initialize a newly allocated zspage */
> >@@ -912,15 +1053,13 @@ static void init_zspage(struct size_class *class, struct zspage *zspage)
> > {
> > 	unsigned int freeobj = 1;
> > 	unsigned long off = 0;
> >-	struct page *page = zspage->first_page;
> >+	struct page *page = get_first_page(zspage);
> >
> > 	while (page) {
> > 		struct page *next_page;
> > 		struct link_free *link;
> > 		void *vaddr;
> >
> >-		set_first_obj_offset(page, off);
> >-
> > 		vaddr = kmap_atomic(page);
> > 		link = (struct link_free *)vaddr + off / sizeof(*link);
> >
> >@@ -952,16 +1091,17 @@ static void init_zspage(struct size_class *class, struct zspage *zspage)
> > 	set_freeobj(zspage, 0);
> > }
> >
> >-static void create_page_chain(struct zspage *zspage, struct page *pages[],
> >-				int nr_pages)
> >+static void create_page_chain(struct size_class *class, struct zspage *zspage,
> >+				struct page *pages[])
> > {
> > 	int i;
> > 	struct page *page;
> > 	struct page *prev_page = NULL;
> >+	int nr_pages = class->pages_per_zspage;
> >
> > 	/*
> > 	 * Allocate individual pages and link them together as:
> >-	 * 1. all pages are linked together using page->next
> >+	 * 1. all pages are linked together using page->freelist
> > 	 * 2. each sub-page point to zspage using page->private
> > 	 *
> > 	 * we set PG_private to identify the first page (i.e. no other sub-page
> >@@ -970,16 +1110,18 @@ static void create_page_chain(struct zspage *zspage, struct page *pages[],
> > 	for (i = 0; i < nr_pages; i++) {
> > 		page = pages[i];
> > 		set_page_private(page, (unsigned long)zspage);
> >+		page->freelist = NULL;
> > 		if (i == 0) {
> > 			zspage->first_page = page;
> > 			SetPagePrivate(page);
> >+			if (unlikely(class->objs_per_zspage == 1 &&
> >+					class->pages_per_zspage == 1))
> >+				SetPageHugeObject(page);
> > 		} else {
> >-			prev_page->next = page;
> >+			prev_page->freelist = page;
> > 		}
> >-		if (i == nr_pages - 1) {
> >+		if (i == nr_pages - 1)
> > 			SetPagePrivate2(page);
> >-			page->next = NULL;
> >-		}
> > 		prev_page = page;
> > 	}
> > }
> >@@ -999,6 +1141,8 @@ static struct zspage *alloc_zspage(struct zs_pool *pool,
> > 		return NULL;
> >
> > 	memset(zspage, 0, sizeof(struct zspage));
> >+	zspage->magic = ZSPAGE_MAGIC;
> >+	migrate_lock_init(zspage);
> >
> > 	for (i = 0; i < class->pages_per_zspage; i++) {
> > 		struct page *page;
> >@@ -1013,7 +1157,7 @@ static struct zspage *alloc_zspage(struct zs_pool *pool,
> > 		pages[i] = page;
> > 	}
> >
> >-	create_page_chain(zspage, pages, class->pages_per_zspage);
> >+	create_page_chain(class, zspage, pages);
> > 	init_zspage(class, zspage);
> >
> > 	return zspage;
> >@@ -1024,7 +1168,7 @@ static struct zspage *find_get_zspage(struct size_class *class)
> > 	int i;
> > 	struct zspage *zspage;
> >
> >-	for (i = ZS_ALMOST_FULL; i <= ZS_ALMOST_EMPTY; i++) {
> >+	for (i = ZS_ALMOST_FULL; i >= ZS_EMPTY; i--) {
> > 		zspage = list_first_entry_or_null(&class->fullness_list[i],
> > 				struct zspage, list);
> > 		if (zspage)
> >@@ -1289,6 +1433,10 @@ void *zs_map_object(struct zs_pool *pool, unsigned long handle,
> > 	obj = handle_to_obj(handle);
> > 	obj_to_location(obj, &page, &obj_idx);
> > 	zspage = get_zspage(page);
> >+
> >+	/* migration cannot move any subpage in this zspage */
> >+	migrate_read_lock(zspage);
> >+
> > 	get_zspage_mapping(zspage, &class_idx, &fg);
> > 	class = pool->size_class[class_idx];
> > 	off = (class->size * obj_idx) & ~PAGE_MASK;
> >@@ -1309,7 +1457,7 @@ void *zs_map_object(struct zs_pool *pool, unsigned long handle,
> >
> > 	ret = __zs_map_object(area, pages, off, class->size);
> > out:
> >-	if (!class->huge)
> >+	if (likely(!PageHugeObject(page)))
> > 		ret += ZS_HANDLE_SIZE;
> >
> > 	return ret;
> >@@ -1348,6 +1496,8 @@ void zs_unmap_object(struct zs_pool *pool, unsigned long handle)
> > 		__zs_unmap_object(area, pages, off, class->size);
> > 	}
> > 	put_cpu_var(zs_map_area);
> >+
> >+	migrate_read_unlock(zspage);
> > 	unpin_tag(handle);
> > }
> > EXPORT_SYMBOL_GPL(zs_unmap_object);
> >@@ -1377,7 +1527,7 @@ static unsigned long obj_malloc(struct size_class *class,
> > 	vaddr = kmap_atomic(m_page);
> > 	link = (struct link_free *)vaddr + m_offset / sizeof(*link);
> > 	set_freeobj(zspage, link->next >> OBJ_ALLOCATED_TAG);
> >-	if (!class->huge)
> >+	if (likely(!PageHugeObject(m_page)))
> > 		/* record handle in the header of allocated chunk */
> > 		link->handle = handle;
> > 	else
> >@@ -1407,6 +1557,7 @@ unsigned long zs_malloc(struct zs_pool *pool, size_t size, gfp_t gfp)
> > {
> > 	unsigned long handle, obj;
> > 	struct size_class *class;
> >+	enum fullness_group newfg;
> > 	struct zspage *zspage;
> >
> > 	if (unlikely(!size || size > ZS_MAX_ALLOC_SIZE))
> >@@ -1422,28 +1573,37 @@ unsigned long zs_malloc(struct zs_pool *pool, size_t size, gfp_t gfp)
> >
> > 	spin_lock(&class->lock);
> > 	zspage = find_get_zspage(class);
> >-
> >-	if (!zspage) {
> >+	if (likely(zspage)) {
> >+		obj = obj_malloc(class, zspage, handle);
> >+		/* Now move the zspage to another fullness group, if required */
> >+		fix_fullness_group(class, zspage);
> >+		record_obj(handle, obj);
> > 		spin_unlock(&class->lock);
> >-		zspage = alloc_zspage(pool, class, gfp);
> >-		if (unlikely(!zspage)) {
> >-			cache_free_handle(pool, handle);
> >-			return 0;
> >-		}
> >
> >-		set_zspage_mapping(zspage, class->index, ZS_EMPTY);
> >-		atomic_long_add(class->pages_per_zspage,
> >-					&pool->pages_allocated);
> >+		return handle;
> >+	}
> >
> >-		spin_lock(&class->lock);
> >-		zs_stat_inc(class, OBJ_ALLOCATED, get_maxobj_per_zspage(
> >-				class->size, class->pages_per_zspage));
> >+	spin_unlock(&class->lock);
> >+
> >+	zspage = alloc_zspage(pool, class, gfp);
> >+	if (!zspage) {
> >+		cache_free_handle(pool, handle);
> >+		return 0;
> > 	}
> >
> >+	spin_lock(&class->lock);
> > 	obj = obj_malloc(class, zspage, handle);
> >-	/* Now move the zspage to another fullness group, if required */
> >-	fix_fullness_group(class, zspage);
> >+	newfg = get_fullness_group(class, zspage);
> >+	insert_zspage(class, zspage, newfg);
> >+	set_zspage_mapping(zspage, class->index, newfg);
> > 	record_obj(handle, obj);
> >+	atomic_long_add(class->pages_per_zspage,
> >+				&pool->pages_allocated);
> >+	zs_stat_inc(class, OBJ_ALLOCATED, get_maxobj_per_zspage(
> >+			class->size, class->pages_per_zspage));
> >+
> >+	/* We completely set up zspage so mark them as movable */
> >+	SetZsPageMovable(pool, zspage);
> > 	spin_unlock(&class->lock);
> >
> > 	return handle;
> >@@ -1484,6 +1644,7 @@ void zs_free(struct zs_pool *pool, unsigned long handle)
> > 	int class_idx;
> > 	struct size_class *class;
> > 	enum fullness_group fullness;
> >+	bool isolated;
> >
> > 	if (unlikely(!handle))
> > 		return;
> >@@ -1493,22 +1654,28 @@ void zs_free(struct zs_pool *pool, unsigned long handle)
> > 	obj_to_location(obj, &f_page, &f_objidx);
> > 	zspage = get_zspage(f_page);
> >
> >+	migrate_read_lock(zspage);
> >+
> > 	get_zspage_mapping(zspage, &class_idx, &fullness);
> > 	class = pool->size_class[class_idx];
> >
> > 	spin_lock(&class->lock);
> > 	obj_free(class, obj);
> > 	fullness = fix_fullness_group(class, zspage);
> >-	if (fullness == ZS_EMPTY) {
> >-		zs_stat_dec(class, OBJ_ALLOCATED, get_maxobj_per_zspage(
> >-				class->size, class->pages_per_zspage));
> >-		atomic_long_sub(class->pages_per_zspage,
> >-				&pool->pages_allocated);
> >-		free_zspage(pool, zspage);
> >+	if (fullness != ZS_EMPTY) {
> >+		migrate_read_unlock(zspage);
> >+		goto out;
> > 	}
> >+
> >+	isolated = is_zspage_isolated(zspage);
> >+	migrate_read_unlock(zspage);
> >+	/* If zspage is isolated, zs_page_putback will free the zspage */
> >+	if (likely(!isolated))
> >+		free_zspage(pool, class, zspage);
> >+out:
> >+
> > 	spin_unlock(&class->lock);
> > 	unpin_tag(handle);
> >-
> > 	cache_free_handle(pool, handle);
> > }
> > EXPORT_SYMBOL_GPL(zs_free);
> >@@ -1587,12 +1754,13 @@ static unsigned long find_alloced_obj(struct size_class *class,
> > 	int offset = 0;
> > 	unsigned long handle = 0;
> > 	void *addr = kmap_atomic(page);
> >+	struct zspage *zspage = get_zspage(page);
> >
> >-	offset = get_first_obj_offset(page);
> >+	offset = get_first_obj_offset(class, get_first_page(zspage), page);
> > 	offset += class->size * index;
> >
> > 	while (offset < PAGE_SIZE) {
> >-		head = obj_to_head(class, page, addr + offset);
> >+		head = obj_to_head(page, addr + offset);
> > 		if (head & OBJ_ALLOCATED_TAG) {
> > 			handle = head & ~OBJ_ALLOCATED_TAG;
> > 			if (trypin_tag(handle))
> >@@ -1684,6 +1852,7 @@ static struct zspage *isolate_zspage(struct size_class *class, bool source)
> > 		zspage = list_first_entry_or_null(&class->fullness_list[fg[i]],
> > 							struct zspage, list);
> > 		if (zspage) {
> >+			VM_BUG_ON(is_zspage_isolated(zspage));
> > 			remove_zspage(class, zspage, fg[i]);
> > 			return zspage;
> > 		}
> >@@ -1704,6 +1873,8 @@ static enum fullness_group putback_zspage(struct size_class *class,
> > {
> > 	enum fullness_group fullness;
> >
> >+	VM_BUG_ON(is_zspage_isolated(zspage));
> >+
> > 	fullness = get_fullness_group(class, zspage);
> > 	insert_zspage(class, zspage, fullness);
> > 	set_zspage_mapping(zspage, class->index, fullness);
> >@@ -1711,6 +1882,377 @@ static enum fullness_group putback_zspage(struct size_class *class,
> > 	return fullness;
> > }
> >
> >+#ifdef CONFIG_COMPACTION
> >+static struct dentry *zs_mount(struct file_system_type *fs_type,
> >+				int flags, const char *dev_name, void *data)
> >+{
> >+	static const struct dentry_operations ops = {
> >+		.d_dname = simple_dname,
> >+	};
> >+
> >+	return mount_pseudo(fs_type, "zsmalloc:", NULL, &ops, ZSMALLOC_MAGIC);
> >+}
> >+
> >+static struct file_system_type zsmalloc_fs = {
> >+	.name		= "zsmalloc",
> >+	.mount		= zs_mount,
> >+	.kill_sb	= kill_anon_super,
> >+};
> >+
> >+static int zsmalloc_mount(void)
> >+{
> >+	int ret = 0;
> >+
> >+	zsmalloc_mnt = kern_mount(&zsmalloc_fs);
> >+	if (IS_ERR(zsmalloc_mnt))
> >+		ret = PTR_ERR(zsmalloc_mnt);
> >+
> >+	return ret;
> >+}
> >+
> >+static void zsmalloc_unmount(void)
> >+{
> >+	kern_unmount(zsmalloc_mnt);
> >+}
> >+
> >+static void migrate_lock_init(struct zspage *zspage)
> >+{
> >+	rwlock_init(&zspage->lock);
> >+}
> >+
> >+static void migrate_read_lock(struct zspage *zspage)
> >+{
> >+	read_lock(&zspage->lock);
> >+}
> >+
> >+static void migrate_read_unlock(struct zspage *zspage)
> >+{
> >+	read_unlock(&zspage->lock);
> >+}
> >+
> >+static void migrate_write_lock(struct zspage *zspage)
> >+{
> >+	write_lock(&zspage->lock);
> >+}
> >+
> >+static void migrate_write_unlock(struct zspage *zspage)
> >+{
> >+	write_unlock(&zspage->lock);
> >+}
> >+
> >+/* Number of isolated subpage for *page migration* in this zspage */
> >+static void inc_zspage_isolation(struct zspage *zspage)
> >+{
> >+	zspage->isolated++;
> >+}
> >+
> >+static void dec_zspage_isolation(struct zspage *zspage)
> >+{
> >+	zspage->isolated--;
> >+}
> >+
> >+static void replace_sub_page(struct size_class *class, struct zspage *zspage,
> >+				struct page *newpage, struct page *oldpage)
> >+{
> >+	struct page *page;
> >+	struct page *pages[ZS_MAX_PAGES_PER_ZSPAGE] = {NULL, };
> >+	int idx = 0;
> >+
> >+	page = get_first_page(zspage);
> >+	do {
> >+		if (page == oldpage)
> >+			pages[idx] = newpage;
> >+		else
> >+			pages[idx] = page;
> >+		idx++;
> >+	} while ((page = get_next_page(page)) != NULL);
> >+
> >+	create_page_chain(class, zspage, pages);
> >+	if (unlikely(PageHugeObject(oldpage)))
> >+		newpage->index = oldpage->index;
> >+	__SetPageMovable(newpage, page_mapping(oldpage));
> >+}
> >+
> >+bool zs_page_isolate(struct page *page, isolate_mode_t mode)
> >+{
> >+	struct zs_pool *pool;
> >+	struct size_class *class;
> >+	int class_idx;
> >+	enum fullness_group fullness;
> >+	struct zspage *zspage;
> >+	struct address_space *mapping;
> >+
> >+	/*
> >+	 * Page is locked so zspage couldn't be destroyed. For detail, look at
> >+	 * lock_zspage in free_zspage.
> >+	 */
> >+	VM_BUG_ON_PAGE(!PageMovable(page), page);
> >+	VM_BUG_ON_PAGE(PageIsolated(page), page);
> >+
> >+	zspage = get_zspage(page);
> >+
> >+	/*
> >+	 * Without class lock, fullness could be stale while class_idx is okay
> >+	 * because class_idx is constant unless page is freed so we should get
> >+	 * fullness again under class lock.
> >+	 */
> >+	get_zspage_mapping(zspage, &class_idx, &fullness);
> >+	mapping = page_mapping(page);
> >+	pool = mapping->private_data;
> >+	class = pool->size_class[class_idx];
> >+
> >+	spin_lock(&class->lock);
> >+	if (get_zspage_inuse(zspage) == 0) {
> >+		spin_unlock(&class->lock);
> >+		return false;
> >+	}
> >+
> >+	/* zspage is isolated for object migration */
> >+	if (list_empty(&zspage->list) && !is_zspage_isolated(zspage)) {
> >+		spin_unlock(&class->lock);
> >+		return false;
> >+	}
> >+
> >+	/*
> >+	 * If this is first time isolation for the zspage, isolate zspage from
> >+	 * size_class to prevent further object allocation from the zspage.
> >+	 */
> >+	if (!list_empty(&zspage->list) && !is_zspage_isolated(zspage)) {
> >+		get_zspage_mapping(zspage, &class_idx, &fullness);
> >+		remove_zspage(class, zspage, fullness);
> >+	}
> >+
> >+	inc_zspage_isolation(zspage);
> >+	spin_unlock(&class->lock);
> >+
> >+	return true;
> >+}
> >+
> >+int zs_page_migrate(struct address_space *mapping, struct page *newpage,
> >+		struct page *page, enum migrate_mode mode)
> >+{
> >+	struct zs_pool *pool;
> >+	struct size_class *class;
> >+	int class_idx;
> >+	enum fullness_group fullness;
> >+	struct zspage *zspage;
> >+	struct page *dummy;
> >+	void *s_addr, *d_addr, *addr;
> >+	int offset, pos;
> >+	unsigned long handle, head;
> >+	unsigned long old_obj, new_obj;
> >+	unsigned int obj_idx;
> >+	int ret = -EAGAIN;
> >+
> >+	VM_BUG_ON_PAGE(!PageMovable(page), page);
> >+	VM_BUG_ON_PAGE(!PageIsolated(page), page);
> >+
> >+	zspage = get_zspage(page);
> >+
> >+	/* Concurrent compactor cannot migrate any subpage in zspage */
> >+	migrate_write_lock(zspage);
> >+	get_zspage_mapping(zspage, &class_idx, &fullness);
> >+	pool = mapping->private_data;
> >+	class = pool->size_class[class_idx];
> >+	offset = get_first_obj_offset(class, get_first_page(zspage), page);
> >+
> >+	spin_lock(&class->lock);
> >+	if (!get_zspage_inuse(zspage)) {
> >+		ret = -EBUSY;
> >+		goto unlock_class;
> >+	}
> >+
> >+	pos = offset;
> >+	s_addr = kmap_atomic(page);
> >+	while (pos < PAGE_SIZE) {
> >+		head = obj_to_head(page, s_addr + pos);
> >+		if (head & OBJ_ALLOCATED_TAG) {
> >+			handle = head & ~OBJ_ALLOCATED_TAG;
> >+			if (!trypin_tag(handle))
> >+				goto unpin_objects;
> >+		}
> >+		pos += class->size;
> >+	}
> >+
> >+	/*
> >+	 * Here, any user cannot access all objects in the zspage so let's move.
> >+	 */
> >+	d_addr = kmap_atomic(newpage);
> >+	memcpy(d_addr, s_addr, PAGE_SIZE);
> >+	kunmap_atomic(d_addr);
> >+
> >+	for (addr = s_addr + offset; addr < s_addr + pos;
> >+					addr += class->size) {
> >+		head = obj_to_head(page, addr);
> >+		if (head & OBJ_ALLOCATED_TAG) {
> >+			handle = head & ~OBJ_ALLOCATED_TAG;
> >+			if (!testpin_tag(handle))
> >+				BUG();
> >+
> >+			old_obj = handle_to_obj(handle);
> >+			obj_to_location(old_obj, &dummy, &obj_idx);
> >+			new_obj = (unsigned long)location_to_obj(newpage,
> >+								obj_idx);
> >+			new_obj |= BIT(HANDLE_PIN_BIT);
> >+			record_obj(handle, new_obj);
> >+		}
> >+	}
> >+
> >+	replace_sub_page(class, zspage, newpage, page);
> >+	get_page(newpage);
> >+
> >+	dec_zspage_isolation(zspage);
> >+
> >+	/*
> >+	 * Page migration is done so let's putback isolated zspage to
> >+	 * the list if @page is final isolated subpage in the zspage.
> >+	 */
> >+	if (!is_zspage_isolated(zspage))
> >+		putback_zspage(class, zspage);
> >+
> >+	reset_page(page);
> >+	put_page(page);
> >+	page = newpage;
> >+
> >+	ret = 0;
> >+unpin_objects:
> >+	for (addr = s_addr + offset; addr < s_addr + pos;
> >+						addr += class->size) {
> >+		head = obj_to_head(page, addr);
> >+		if (head & OBJ_ALLOCATED_TAG) {
> >+			handle = head & ~OBJ_ALLOCATED_TAG;
> >+			if (!testpin_tag(handle))
> >+				BUG();
> >+			unpin_tag(handle);
> >+		}
> >+	}
> >+	kunmap_atomic(s_addr);
> >+unlock_class:
> >+	spin_unlock(&class->lock);
> >+	migrate_write_unlock(zspage);
> >+
> >+	return ret;
> >+}
> >+
> >+void zs_page_putback(struct page *page)
> >+{
> >+	struct zs_pool *pool;
> >+	struct size_class *class;
> >+	int class_idx;
> >+	enum fullness_group fg;
> >+	struct address_space *mapping;
> >+	struct zspage *zspage;
> >+
> >+	VM_BUG_ON_PAGE(!PageMovable(page), page);
> >+	VM_BUG_ON_PAGE(!PageIsolated(page), page);
> >+
> >+	zspage = get_zspage(page);
> >+	get_zspage_mapping(zspage, &class_idx, &fg);
> >+	mapping = page_mapping(page);
> >+	pool = mapping->private_data;
> >+	class = pool->size_class[class_idx];
> >+
> >+	spin_lock(&class->lock);
> >+	dec_zspage_isolation(zspage);
> >+	if (!is_zspage_isolated(zspage)) {
> >+		fg = putback_zspage(class, zspage);
> >+		/*
> >+		 * Due to page_lock, we cannot free zspage immediately
> >+		 * so let's defer.
> >+		 */
> >+		if (fg == ZS_EMPTY)
> >+			schedule_work(&pool->free_work);
> >+	}
> >+	spin_unlock(&class->lock);
> >+}
> >+
> >+const struct address_space_operations zsmalloc_aops = {
> >+	.isolate_page = zs_page_isolate,
> >+	.migratepage = zs_page_migrate,
> >+	.putback_page = zs_page_putback,
> >+};
> >+
> >+static int zs_register_migration(struct zs_pool *pool)
> >+{
> >+	pool->inode = alloc_anon_inode(zsmalloc_mnt->mnt_sb);
> >+	if (IS_ERR(pool->inode)) {
> >+		pool->inode = NULL;
> >+		return 1;
> >+	}
> >+
> >+	pool->inode->i_mapping->private_data = pool;
> >+	pool->inode->i_mapping->a_ops = &zsmalloc_aops;
> >+	return 0;
> >+}
> >+
> >+static void zs_unregister_migration(struct zs_pool *pool)
> >+{
> >+	flush_work(&pool->free_work);
> >+	if (pool->inode)
> >+		iput(pool->inode);
> >+}
> >+
> >+/*
> >+ * Caller should hold page_lock of all pages in the zspage
> >+ * In here, we cannot use zspage meta data.
> >+ */
> >+static void async_free_zspage(struct work_struct *work)
> >+{
> >+	int i;
> >+	struct size_class *class;
> >+	unsigned int class_idx;
> >+	enum fullness_group fullness;
> >+	struct zspage *zspage, *tmp;
> >+	LIST_HEAD(free_pages);
> >+	struct zs_pool *pool = container_of(work, struct zs_pool,
> >+					free_work);
> >+
> >+	for (i = 0; i < zs_size_classes; i++) {
> >+		class = pool->size_class[i];
> >+		if (class->index != i)
> >+			continue;
> >+
> >+		spin_lock(&class->lock);
> >+		list_splice_init(&class->fullness_list[ZS_EMPTY], &free_pages);
> >+		spin_unlock(&class->lock);
> >+	}
> >+
> >+
> >+	list_for_each_entry_safe(zspage, tmp, &free_pages, list) {
> >+		list_del(&zspage->list);
> >+		lock_zspage(zspage);
> >+
> >+		get_zspage_mapping(zspage, &class_idx, &fullness);
> >+		VM_BUG_ON(fullness != ZS_EMPTY);
> >+		class = pool->size_class[class_idx];
> >+		spin_lock(&class->lock);
> >+		__free_zspage(pool, pool->size_class[class_idx], zspage);
> >+		spin_unlock(&class->lock);
> >+	}
> >+};
> >+
> >+static void kick_deferred_free(struct zs_pool *pool)
> >+{
> >+	schedule_work(&pool->free_work);
> >+}
> >+
> >+static void init_deferred_free(struct zs_pool *pool)
> >+{
> >+	INIT_WORK(&pool->free_work, async_free_zspage);
> >+}
> >+
> >+static void SetZsPageMovable(struct zs_pool *pool, struct zspage *zspage)
> >+{
> >+	struct page *page = get_first_page(zspage);
> >+
> >+	do {
> >+		WARN_ON(!trylock_page(page));
> >+		__SetPageMovable(page, pool->inode->i_mapping);
> >+		unlock_page(page);
> >+	} while ((page = get_next_page(page)) != NULL);
> >+}
> >+#endif
> >+
> > /*
> >  *
> >  * Based on the number of unused allocated objects calculate
> >@@ -1745,10 +2287,10 @@ static void __zs_compact(struct zs_pool *pool, struct size_class *class)
> > 			break;
> >
> > 		cc.index = 0;
> >-		cc.s_page = src_zspage->first_page;
> >+		cc.s_page = get_first_page(src_zspage);
> >
> > 		while ((dst_zspage = isolate_zspage(class, false))) {
> >-			cc.d_page = dst_zspage->first_page;
> >+			cc.d_page = get_first_page(dst_zspage);
> > 			/*
> > 			 * If there is no more space in dst_page, resched
> > 			 * and see if anyone had allocated another zspage.
> >@@ -1765,11 +2307,7 @@ static void __zs_compact(struct zs_pool *pool, struct size_class *class)
> >
> > 		putback_zspage(class, dst_zspage);
> > 		if (putback_zspage(class, src_zspage) == ZS_EMPTY) {
> >-			zs_stat_dec(class, OBJ_ALLOCATED, get_maxobj_per_zspage(
> >-					class->size, class->pages_per_zspage));
> >-			atomic_long_sub(class->pages_per_zspage,
> >-					&pool->pages_allocated);
> >-			free_zspage(pool, src_zspage);
> >+			free_zspage(pool, class, src_zspage);
> > 			pool->stats.pages_compacted += class->pages_per_zspage;
> > 		}
> > 		spin_unlock(&class->lock);
> >@@ -1885,6 +2423,7 @@ struct zs_pool *zs_create_pool(const char *name)
> > 	if (!pool)
> > 		return NULL;
> >
> >+	init_deferred_free(pool);
> > 	pool->size_class = kcalloc(zs_size_classes, sizeof(struct size_class *),
> > 			GFP_KERNEL);
> > 	if (!pool->size_class) {
> >@@ -1939,12 +2478,10 @@ struct zs_pool *zs_create_pool(const char *name)
> > 		class->pages_per_zspage = pages_per_zspage;
> > 		class->objs_per_zspage = class->pages_per_zspage *
> > 						PAGE_SIZE / class->size;
> >-		if (pages_per_zspage == 1 && class->objs_per_zspage == 1)
> >-			class->huge = true;
> > 		spin_lock_init(&class->lock);
> > 		pool->size_class[i] = class;
> >-		for (fullness = ZS_ALMOST_FULL; fullness <= ZS_ALMOST_EMPTY;
> >-								fullness++)
> >+		for (fullness = ZS_EMPTY; fullness < NR_ZS_FULLNESS;
> >+							fullness++)
> > 			INIT_LIST_HEAD(&class->fullness_list[fullness]);
> >
> > 		prev_class = class;
> >@@ -1953,6 +2490,9 @@ struct zs_pool *zs_create_pool(const char *name)
> > 	/* debug only, don't abort if it fails */
> > 	zs_pool_stat_create(pool, name);
> >
> >+	if (zs_register_migration(pool))
> >+		goto err;
> >+
> > 	/*
> > 	 * Not critical, we still can use the pool
> > 	 * and user can trigger compaction manually.
> >@@ -1972,6 +2512,7 @@ void zs_destroy_pool(struct zs_pool *pool)
> > 	int i;
> >
> > 	zs_unregister_shrinker(pool);
> >+	zs_unregister_migration(pool);
> > 	zs_pool_stat_destroy(pool);
> >
> > 	for (i = 0; i < zs_size_classes; i++) {
> >@@ -1984,7 +2525,7 @@ void zs_destroy_pool(struct zs_pool *pool)
> > 		if (class->index != i)
> > 			continue;
> >
> >-		for (fg = ZS_ALMOST_FULL; fg <= ZS_ALMOST_EMPTY; fg++) {
> >+		for (fg = ZS_EMPTY; fg < NR_ZS_FULLNESS; fg++) {
> > 			if (!list_empty(&class->fullness_list[fg])) {
> > 				pr_info("Freeing non-empty class with size %db, fullness group %d\n",
> > 					class->size, fg);
> >@@ -2002,7 +2543,13 @@ EXPORT_SYMBOL_GPL(zs_destroy_pool);
> >
> > static int __init zs_init(void)
> > {
> >-	int ret = zs_register_cpu_notifier();
> >+	int ret;
> >+
> >+	ret = zsmalloc_mount();
> >+	if (ret)
> >+		goto out;
> >+
> >+	ret = zs_register_cpu_notifier();
> >
> > 	if (ret)
> > 		goto notifier_fail;
> >@@ -2019,7 +2566,8 @@ static int __init zs_init(void)
> >
> > notifier_fail:
> > 	zs_unregister_cpu_notifier();
> >-
> >+	zsmalloc_unmount();
> >+out:
> > 	return ret;
> > }
> >
> >@@ -2028,6 +2576,7 @@ static void __exit zs_exit(void)
> > #ifdef CONFIG_ZPOOL
> > 	zpool_unregister_driver(&zs_zpool_driver);
> > #endif
> >+	zsmalloc_unmount();
> > 	zs_unregister_cpu_notifier();
> >
> > 	zs_stat_exit();
> >
> 
> --
> 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: <a href=mailto:"dont@kvack.org"> email@kvack.org </a>

--
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: <a href=mailto:"dont@kvack.org"> email@kvack.org </a>