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Commit bfd093f5 authored by Minchan Kim's avatar Minchan Kim Committed by Linus Torvalds
Browse files

zsmalloc: use freeobj for index 

Zsmalloc stores first free object's <PFN, obj_idx> position into freeobj
in each zspage.  If we change it with index from first_page instead of
position, it makes page migration simple because we don't need to
correct other entries for linked list if a page is migrated out.

Link: http://lkml.kernel.org/r/1464736881-24886-11-git-send-email-minchan@kernel.org


Signed-off-by: default avatarMinchan Kim <minchan@kernel.org>
Cc: Sergey Senozhatsky <sergey.senozhatsky@gmail.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent 4aa409ca

mm/zsmalloc.c

+73 −66
Original line number Diff line number Diff line
@@ -71,9 +71,7 @@ 
 * Object location (<PFN>, <obj_idx>) is encoded as

 * as single (unsigned long) handle value.

 *

 * Note that object index <obj_idx> is relative to system

 * page <PFN> it is stored in, so for each sub-page belonging

 * to a zspage, obj_idx starts with 0.

 * Note that object index <obj_idx> starts from 0.

 *

 * This is made more complicated by various memory models and PAE.

 */
@@ -214,10 +212,10 @@ struct size_class { 
struct link_free {

	union {

		/*

		 * Position of next free chunk (encodes <PFN, obj_idx>)

		 * Free object index;

		 * It's valid for non-allocated object

		 */

		void *next;

		unsigned long next;

		/*

		 * Handle of allocated object.

		 */
@@ -261,7 +259,7 @@ struct zspage { 
		unsigned int class:CLASS_BITS;

	};

	unsigned int inuse;

	void *freeobj;

	unsigned int freeobj;

	struct page *first_page;

	struct list_head list; /* fullness list */

};
@@ -459,14 +457,14 @@ static inline void set_first_obj_offset(struct page *page, int offset) 
	page->index = offset;

}



static inline unsigned long get_freeobj(struct zspage *zspage)

static inline unsigned int get_freeobj(struct zspage *zspage)

{

	return (unsigned long)zspage->freeobj;

	return zspage->freeobj;

}



static inline void set_freeobj(struct zspage *zspage, unsigned long obj)

static inline void set_freeobj(struct zspage *zspage, unsigned int obj)

{

	zspage->freeobj = (void *)obj;

	zspage->freeobj = obj;

}



static void get_zspage_mapping(struct zspage *zspage,
@@ -810,6 +808,10 @@ static int get_pages_per_zspage(int class_size) 
	return max_usedpc_order;

}



static struct page *get_first_page(struct zspage *zspage)

{

	return zspage->first_page;

}



static struct zspage *get_zspage(struct page *page)

{
@@ -821,37 +823,33 @@ static struct page *get_next_page(struct page *page) 
	return page->next;

}



/*

 * Encode <page, obj_idx> as a single handle value.

 * We use the least bit of handle for tagging.

/**

 * obj_to_location - get (<page>, <obj_idx>) from encoded object value

 * @page: page object resides in zspage

 * @obj_idx: object index

 */

static void *location_to_obj(struct page *page, unsigned long obj_idx)

static void obj_to_location(unsigned long obj, struct page **page,

				unsigned int *obj_idx)

{

	unsigned long obj;



	if (!page) {

		VM_BUG_ON(obj_idx);

		return NULL;

	obj >>= OBJ_TAG_BITS;

	*page = pfn_to_page(obj >> OBJ_INDEX_BITS);

	*obj_idx = (obj & OBJ_INDEX_MASK);

}



/**

 * location_to_obj - get obj value encoded from (<page>, <obj_idx>)

 * @page: page object resides in zspage

 * @obj_idx: object index

 */

static unsigned long location_to_obj(struct page *page, unsigned int obj_idx)

{

	unsigned long obj;



	obj = page_to_pfn(page) << OBJ_INDEX_BITS;

	obj |= ((obj_idx) & OBJ_INDEX_MASK);

	obj |= obj_idx & OBJ_INDEX_MASK;

	obj <<= OBJ_TAG_BITS;



	return (void *)obj;

}



/*

 * Decode <page, obj_idx> pair from the given object handle. We adjust the

 * decoded obj_idx back to its original value since it was adjusted in

 * location_to_obj().

 */

static void obj_to_location(unsigned long obj, struct page **page,

				unsigned long *obj_idx)

{

	obj >>= OBJ_TAG_BITS;

	*page = pfn_to_page(obj >> OBJ_INDEX_BITS);

	*obj_idx = (obj & OBJ_INDEX_MASK);

	return obj;

}



static unsigned long handle_to_obj(unsigned long handle)
@@ -869,16 +867,6 @@ static unsigned long obj_to_head(struct size_class *class, struct page *page, 
		return *(unsigned long *)obj;

}



static unsigned long obj_idx_to_offset(struct page *page,

				unsigned long obj_idx, int class_size)

{

	unsigned long off;



	off = get_first_obj_offset(page);



	return off + obj_idx * class_size;

}



static inline int trypin_tag(unsigned long handle)

{

	return bit_spin_trylock(HANDLE_PIN_BIT, (unsigned long *)handle);
@@ -922,13 +910,13 @@ static void free_zspage(struct zs_pool *pool, struct zspage *zspage) 
/* Initialize a newly allocated zspage */

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;



	while (page) {

		struct page *next_page;

		struct link_free *link;

		unsigned int i = 1;

		void *vaddr;



		set_first_obj_offset(page, off);
@@ -937,7 +925,7 @@ static void init_zspage(struct size_class *class, struct zspage *zspage) 
		link = (struct link_free *)vaddr + off / sizeof(*link);



		while ((off += class->size) < PAGE_SIZE) {

			link->next = location_to_obj(page, i++);

			link->next = freeobj++ << OBJ_ALLOCATED_TAG;

			link += class->size / sizeof(*link);

		}
@@ -947,14 +935,21 @@ static void init_zspage(struct size_class *class, struct zspage *zspage) 
		 * page (if present)

		 */

		next_page = get_next_page(page);

		link->next = location_to_obj(next_page, 0);

		if (next_page) {

			link->next = freeobj++ << OBJ_ALLOCATED_TAG;

		} else {

			/*

			 * Reset OBJ_ALLOCATED_TAG bit to last link to tell

			 * whether it's allocated object or not.

			 */

			link->next = -1 << OBJ_ALLOCATED_TAG;

		}

		kunmap_atomic(vaddr);

		page = next_page;

		off %= PAGE_SIZE;

	}



	set_freeobj(zspage,

		(unsigned long)location_to_obj(zspage->first_page, 0));

	set_freeobj(zspage, 0);

}



static void create_page_chain(struct zspage *zspage, struct page *pages[],
@@ -1271,7 +1266,8 @@ void *zs_map_object(struct zs_pool *pool, unsigned long handle, 
{

	struct zspage *zspage;

	struct page *page;

	unsigned long obj, obj_idx, off;

	unsigned long obj, off;

	unsigned int obj_idx;



	unsigned int class_idx;

	enum fullness_group fg;
@@ -1295,7 +1291,7 @@ void *zs_map_object(struct zs_pool *pool, unsigned long handle, 
	zspage = get_zspage(page);

	get_zspage_mapping(zspage, &class_idx, &fg);

	class = pool->size_class[class_idx];

	off = obj_idx_to_offset(page, obj_idx, class->size);

	off = (class->size * obj_idx) & ~PAGE_MASK;



	area = &get_cpu_var(zs_map_area);

	area->vm_mm = mm;
@@ -1324,7 +1320,8 @@ void zs_unmap_object(struct zs_pool *pool, unsigned long handle) 
{

	struct zspage *zspage;

	struct page *page;

	unsigned long obj, obj_idx, off;

	unsigned long obj, off;

	unsigned int obj_idx;



	unsigned int class_idx;

	enum fullness_group fg;
@@ -1336,7 +1333,7 @@ void zs_unmap_object(struct zs_pool *pool, unsigned long handle) 
	zspage = get_zspage(page);

	get_zspage_mapping(zspage, &class_idx, &fg);

	class = pool->size_class[class_idx];

	off = obj_idx_to_offset(page, obj_idx, class->size);

	off = (class->size * obj_idx) & ~PAGE_MASK;



	area = this_cpu_ptr(&zs_map_area);

	if (off + class->size <= PAGE_SIZE)
@@ -1358,21 +1355,28 @@ EXPORT_SYMBOL_GPL(zs_unmap_object); 
static unsigned long obj_malloc(struct size_class *class,

				struct zspage *zspage, unsigned long handle)

{

	int i, nr_page, offset;

	unsigned long obj;

	struct link_free *link;



	struct page *m_page;

	unsigned long m_objidx, m_offset;

	unsigned long m_offset;

	void *vaddr;



	handle |= OBJ_ALLOCATED_TAG;

	obj = get_freeobj(zspage);

	obj_to_location(obj, &m_page, &m_objidx);

	m_offset = obj_idx_to_offset(m_page, m_objidx, class->size);



	offset = obj * class->size;

	nr_page = offset >> PAGE_SHIFT;

	m_offset = offset & ~PAGE_MASK;

	m_page = get_first_page(zspage);



	for (i = 0; i < nr_page; i++)

		m_page = get_next_page(m_page);



	vaddr = kmap_atomic(m_page);

	link = (struct link_free *)vaddr + m_offset / sizeof(*link);

	set_freeobj(zspage, (unsigned long)link->next);

	set_freeobj(zspage, link->next >> OBJ_ALLOCATED_TAG);

	if (!class->huge)

		/* record handle in the header of allocated chunk */

		link->handle = handle;
@@ -1384,6 +1388,8 @@ static unsigned long obj_malloc(struct size_class *class, 
	mod_zspage_inuse(zspage, 1);

	zs_stat_inc(class, OBJ_USED, 1);



	obj = location_to_obj(m_page, obj);



	return obj;

}
@@ -1449,22 +1455,22 @@ static void obj_free(struct size_class *class, unsigned long obj) 
	struct link_free *link;

	struct zspage *zspage;

	struct page *f_page;

	unsigned long f_objidx, f_offset;

	unsigned long f_offset;

	unsigned int f_objidx;

	void *vaddr;



	obj &= ~OBJ_ALLOCATED_TAG;

	obj_to_location(obj, &f_page, &f_objidx);

	f_offset = (class->size * f_objidx) & ~PAGE_MASK;

	zspage = get_zspage(f_page);



	f_offset = obj_idx_to_offset(f_page, f_objidx, class->size);



	vaddr = kmap_atomic(f_page);



	/* Insert this object in containing zspage's freelist */

	link = (struct link_free *)(vaddr + f_offset);

	link->next = (void *)get_freeobj(zspage);

	link->next = get_freeobj(zspage) << OBJ_ALLOCATED_TAG;

	kunmap_atomic(vaddr);

	set_freeobj(zspage, obj);

	set_freeobj(zspage, f_objidx);

	mod_zspage_inuse(zspage, -1);

	zs_stat_dec(class, OBJ_USED, 1);

}
@@ -1473,7 +1479,8 @@ void zs_free(struct zs_pool *pool, unsigned long handle) 
{

	struct zspage *zspage;

	struct page *f_page;

	unsigned long obj, f_objidx;

	unsigned long obj;

	unsigned int f_objidx;

	int class_idx;

	struct size_class *class;

	enum fullness_group fullness;
@@ -1510,7 +1517,7 @@ static void zs_object_copy(struct size_class *class, unsigned long dst, 
				unsigned long src)

{

	struct page *s_page, *d_page;

	unsigned long s_objidx, d_objidx;

	unsigned int s_objidx, d_objidx;

	unsigned long s_off, d_off;

	void *s_addr, *d_addr;

	int s_size, d_size, size;
@@ -1521,8 +1528,8 @@ static void zs_object_copy(struct size_class *class, unsigned long dst, 
	obj_to_location(src, &s_page, &s_objidx);

	obj_to_location(dst, &d_page, &d_objidx);



	s_off = obj_idx_to_offset(s_page, s_objidx, class->size);

	d_off = obj_idx_to_offset(d_page, d_objidx, class->size);

	s_off = (class->size * s_objidx) & ~PAGE_MASK;

	d_off = (class->size * d_objidx) & ~PAGE_MASK;



	if (s_off + class->size > PAGE_SIZE)

		s_size = PAGE_SIZE - s_off;