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mm/zsmalloc: simplify zs_max_alloc_size handling

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Commit 40f9fb8cffc6 ("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: Jerome Marchand <jmarchan@redhat.com>
Acked-by: Minchan Kim <minchan@kernel.org>
Cc: Sergey Senozhatsky <sergey.senozhatsky.work@gmail.com>
Cc: Mahendran Ganesh <opensource.ganesh@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Jerome Marchand 2017-07-10 15:50:18 -07:00 committed by prashantpaddune
parent af932b718d
commit c170ea8fd2
1 changed files with 15 additions and 37 deletions
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52
mm/zsmalloc.c
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@ -115,6 +115,11 @@
#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 \
@ -136,6 +141,8 @@
* (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,
@ -173,11 +180,6 @@ static int zs_page_migration_enabled = 1;
static int zs_page_migration_enabled;
#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
@ -250,7 +252,7 @@ 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;
@ -274,11 +276,6 @@ 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;
@ -561,7 +558,7 @@ 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);
}
/* type can be of enum type zs_stat_type or fullness_group */
@ -623,7 +620,7 @@ 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)
@ -1346,17 +1343,6 @@ static void zs_unregister_cpu_notifier(void)
cpu_notifier_register_done();
}
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)
{
@ -2228,7 +2214,7 @@ 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;
@ -2346,7 +2332,7 @@ 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;
@ -2392,7 +2378,7 @@ 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;
@ -2444,12 +2430,6 @@ 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)
@ -2462,7 +2442,7 @@ 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;
@ -2557,7 +2537,7 @@ 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];
@ -2596,8 +2576,6 @@ static int __init zs_init(void)
if (ret)
goto notifier_fail;
init_zs_size_classes();
#ifdef CONFIG_ZPOOL
zpool_register_driver(&zs_zpool_driver);
#endif