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Commit cf8e0fed authored by Jerome Marchand's avatar Jerome Marchand Committed by Linus Torvalds
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mm/zsmalloc: simplify zs_max_alloc_size handling 

Commit 40f9fb8c ("mm/zsmalloc: support allocating obj with size of
ZS_MAX_ALLOC_SIZE") fixes a size calculation error that prevented
zsmalloc to allocate an object of the maximal size (ZS_MAX_ALLOC_SIZE).
I think however the fix is unneededly complicated.

This patch replaces the dynamic calculation of zs_size_classes at init
time by a compile time calculation that uses the DIV_ROUND_UP() macro
already used in get_size_class_index().

[akpm@linux-foundation.org: use min_t]
Link: http://lkml.kernel.org/r/20170630114859.1979-1-jmarchan@redhat.com


Signed-off-by: default avatarJerome Marchand <jmarchan@redhat.com>
Acked-by: default avatarMinchan Kim <minchan@kernel.org>
Cc: Sergey Senozhatsky <sergey.senozhatsky.work@gmail.com>
Cc: Mahendran Ganesh <opensource.ganesh@gmail.com>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent bc1bb362

mm/zsmalloc.c

+15 −37
Original line number Diff line number Diff line
@@ -116,6 +116,11 @@ 
#define OBJ_INDEX_BITS	(BITS_PER_LONG - _PFN_BITS - OBJ_TAG_BITS)

#define OBJ_INDEX_MASK	((_AC(1, UL) << OBJ_INDEX_BITS) - 1)



#define FULLNESS_BITS	2

#define CLASS_BITS	8

#define ISOLATED_BITS	3

#define MAGIC_VAL_BITS	8



#define MAX(a, b) ((a) >= (b) ? (a) : (b))

/* ZS_MIN_ALLOC_SIZE must be multiple of ZS_ALIGN */

#define ZS_MIN_ALLOC_SIZE \
@@ -137,6 +142,8 @@ 
 *  (reason above)

 */

#define ZS_SIZE_CLASS_DELTA	(PAGE_SIZE >> CLASS_BITS)

#define ZS_SIZE_CLASSES	(DIV_ROUND_UP(ZS_MAX_ALLOC_SIZE - ZS_MIN_ALLOC_SIZE, \

				      ZS_SIZE_CLASS_DELTA) + 1)



enum fullness_group {

	ZS_EMPTY,
@@ -168,11 +175,6 @@ static struct dentry *zs_stat_root; 
static struct vfsmount *zsmalloc_mnt;

#endif



/*

 * number of size_classes

 */

static int zs_size_classes;



/*

 * We assign a page to ZS_ALMOST_EMPTY fullness group when:

 *	n <= N / f, where
@@ -244,7 +246,7 @@ struct link_free { 
struct zs_pool {

	const char *name;



	struct size_class **size_class;

	struct size_class *size_class[ZS_SIZE_CLASSES];

	struct kmem_cache *handle_cachep;

	struct kmem_cache *zspage_cachep;
@@ -268,11 +270,6 @@ struct zs_pool { 
#endif

};



#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;
@@ -551,7 +548,7 @@ static int get_size_class_index(int size) 
		idx = DIV_ROUND_UP(size - ZS_MIN_ALLOC_SIZE,

				ZS_SIZE_CLASS_DELTA);



	return min(zs_size_classes - 1, idx);

	return min_t(int, ZS_SIZE_CLASSES - 1, idx);

}



static inline void zs_stat_inc(struct size_class *class,
@@ -610,7 +607,7 @@ static int zs_stats_size_show(struct seq_file *s, void *v) 
			"obj_allocated", "obj_used", "pages_used",

			"pages_per_zspage", "freeable");



	for (i = 0; i < zs_size_classes; i++) {

	for (i = 0; i < ZS_SIZE_CLASSES; i++) {

		class = pool->size_class[i];



		if (class->index != i)
@@ -1294,17 +1291,6 @@ static int zs_cpu_dead(unsigned int cpu) 
	return 0;

}



static void __init init_zs_size_classes(void)

{

	int nr;



	nr = (ZS_MAX_ALLOC_SIZE - ZS_MIN_ALLOC_SIZE) / ZS_SIZE_CLASS_DELTA + 1;

	if ((ZS_MAX_ALLOC_SIZE - ZS_MIN_ALLOC_SIZE) % ZS_SIZE_CLASS_DELTA)

		nr += 1;



	zs_size_classes = nr;

}



static bool can_merge(struct size_class *prev, int pages_per_zspage,

					int objs_per_zspage)

{
@@ -2145,7 +2131,7 @@ static void async_free_zspage(struct work_struct *work) 
	struct zs_pool *pool = container_of(work, struct zs_pool,

					free_work);



	for (i = 0; i < zs_size_classes; i++) {

	for (i = 0; i < ZS_SIZE_CLASSES; i++) {

		class = pool->size_class[i];

		if (class->index != i)

			continue;
@@ -2263,7 +2249,7 @@ unsigned long zs_compact(struct zs_pool *pool) 
	int i;

	struct size_class *class;



	for (i = zs_size_classes - 1; i >= 0; i--) {

	for (i = ZS_SIZE_CLASSES - 1; i >= 0; i--) {

		class = pool->size_class[i];

		if (!class)

			continue;
@@ -2309,7 +2295,7 @@ static unsigned long zs_shrinker_count(struct shrinker *shrinker, 
	struct zs_pool *pool = container_of(shrinker, struct zs_pool,

			shrinker);



	for (i = zs_size_classes - 1; i >= 0; i--) {

	for (i = ZS_SIZE_CLASSES - 1; i >= 0; i--) {

		class = pool->size_class[i];

		if (!class)

			continue;
@@ -2361,12 +2347,6 @@ struct zs_pool *zs_create_pool(const char *name) 
		return NULL;



	init_deferred_free(pool);

	pool->size_class = kcalloc(zs_size_classes, sizeof(struct size_class *),

			GFP_KERNEL);

	if (!pool->size_class) {

		kfree(pool);

		return NULL;

	}



	pool->name = kstrdup(name, GFP_KERNEL);

	if (!pool->name)
@@ -2379,7 +2359,7 @@ struct zs_pool *zs_create_pool(const char *name) 
	 * Iterate reversely, because, size of size_class that we want to use

	 * for merging should be larger or equal to current size.

	 */

	for (i = zs_size_classes - 1; i >= 0; i--) {

	for (i = ZS_SIZE_CLASSES - 1; i >= 0; i--) {

		int size;

		int pages_per_zspage;

		int objs_per_zspage;
@@ -2453,7 +2433,7 @@ void zs_destroy_pool(struct zs_pool *pool) 
	zs_unregister_migration(pool);

	zs_pool_stat_destroy(pool);



	for (i = 0; i < zs_size_classes; i++) {

	for (i = 0; i < ZS_SIZE_CLASSES; i++) {

		int fg;

		struct size_class *class = pool->size_class[i];
@@ -2492,8 +2472,6 @@ static int __init zs_init(void) 
	if (ret)

		goto hp_setup_fail;



	init_zs_size_classes();



#ifdef CONFIG_ZPOOL

	zpool_register_driver(&zs_zpool_driver);

#endif