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mm/slab: kmalloc: pass requests larger than order-1 page to page allocator

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There is not much benefit for serving large objects in kmalloc().
Let's pass large requests to page allocator like SLUB for better
maintenance of common code.

Signed-off-by: Hyeonggon Yoo <42.hyeyoo@gmail.com>
Reviewed-by: Vlastimil Babka <vbabka@suse.cz>
Signed-off-by: Vlastimil Babka <vbabka@suse.cz>
This commit is contained in:
Hyeonggon Yoo 2022-08-17 19:18:19 +09:00 committed by Vlastimil Babka
parent c4cab55752
commit d6a71648db
5 changed files with 68 additions and 62 deletions
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23
include/linux/slab.h
View File

@ -243,27 +243,17 @@ static inline unsigned int arch_slab_minalign(void)
#ifdef CONFIG_SLAB
/*
* The largest kmalloc size supported by the SLAB allocators is
* 32 megabyte (2^25) or the maximum allocatable page order if that is
* less than 32 MB.
*
* WARNING: Its not easy to increase this value since the allocators have
* to do various tricks to work around compiler limitations in order to
* ensure proper constant folding.
* SLAB and SLUB directly allocates requests fitting in to an order-1 page
* (PAGE_SIZE*2). Larger requests are passed to the page allocator.
*/
#define KMALLOC_SHIFT_HIGH ((MAX_ORDER + PAGE_SHIFT - 1) <= 25 ? \
(MAX_ORDER + PAGE_SHIFT - 1) : 25)
#define KMALLOC_SHIFT_MAX KMALLOC_SHIFT_HIGH
#define KMALLOC_SHIFT_HIGH (PAGE_SHIFT + 1)
#define KMALLOC_SHIFT_MAX (MAX_ORDER + PAGE_SHIFT - 1)
#ifndef KMALLOC_SHIFT_LOW
#define KMALLOC_SHIFT_LOW 5
#endif
#endif
#ifdef CONFIG_SLUB
/*
* SLUB directly allocates requests fitting in to an order-1 page
* (PAGE_SIZE*2). Larger requests are passed to the page allocator.
*/
#define KMALLOC_SHIFT_HIGH (PAGE_SHIFT + 1)
#define KMALLOC_SHIFT_MAX (MAX_ORDER + PAGE_SHIFT - 1)
#ifndef KMALLOC_SHIFT_LOW
@ -415,10 +405,6 @@ static __always_inline unsigned int __kmalloc_index(size_t size,
if (size <= 512 * 1024) return 19;
if (size <= 1024 * 1024) return 20;
if (size <= 2 * 1024 * 1024) return 21;
if (size <= 4 * 1024 * 1024) return 22;
if (size <= 8 * 1024 * 1024) return 23;
if (size <= 16 * 1024 * 1024) return 24;
if (size <= 32 * 1024 * 1024) return 25;
if (!IS_ENABLED(CONFIG_PROFILE_ALL_BRANCHES) && size_is_constant)
BUILD_BUG_ON_MSG(1, "unexpected size in kmalloc_index()");
@ -428,6 +414,7 @@ static __always_inline unsigned int __kmalloc_index(size_t size,
/* Will never be reached. Needed because the compiler may complain */
return -1;
}
static_assert(PAGE_SHIFT <= 20);
#define kmalloc_index(s) __kmalloc_index(s, true)
#endif /* !CONFIG_SLOB */

60
mm/slab.c
View File

@ -3585,11 +3585,19 @@ __do_kmalloc_node(size_t size, gfp_t flags, int node, unsigned long caller)
struct kmem_cache *cachep;
void *ret;
if (unlikely(size > KMALLOC_MAX_CACHE_SIZE))
return NULL;
if (unlikely(size > KMALLOC_MAX_CACHE_SIZE)) {
ret = kmalloc_large_node_notrace(size, flags, node);
trace_kmalloc_node(caller, ret, NULL, size,
PAGE_SIZE << get_order(size),
flags, node);
return ret;
}
cachep = kmalloc_slab(size, flags);
if (unlikely(ZERO_OR_NULL_PTR(cachep)))
return cachep;
ret = kmem_cache_alloc_node_trace(cachep, flags, node, size);
ret = kasan_kmalloc(cachep, ret, size, flags);
@ -3664,17 +3672,27 @@ EXPORT_SYMBOL(kmem_cache_free);
void kmem_cache_free_bulk(struct kmem_cache *orig_s, size_t size, void **p)
{
struct kmem_cache *s;
size_t i;
local_irq_disable();
for (i = 0; i < size; i++) {
for (int i = 0; i < size; i++) {
void *objp = p[i];
struct kmem_cache *s;
if (!orig_s) /* called via kfree_bulk */
s = virt_to_cache(objp);
else
if (!orig_s) {
struct folio *folio = virt_to_folio(objp);
/* called via kfree_bulk */
if (!folio_test_slab(folio)) {
local_irq_enable();
free_large_kmalloc(folio, objp);
local_irq_disable();
continue;
}
s = folio_slab(folio)->slab_cache;
} else {
s = cache_from_obj(orig_s, objp);
}
if (!s)
continue;
@ -3703,20 +3721,24 @@ void kfree(const void *objp)
{
struct kmem_cache *c;
unsigned long flags;
struct folio *folio;
trace_kfree(_RET_IP_, objp);
if (unlikely(ZERO_OR_NULL_PTR(objp)))
return;
local_irq_save(flags);
kfree_debugcheck(objp);
c = virt_to_cache(objp);
if (!c) {
local_irq_restore(flags);
folio = virt_to_folio(objp);
if (!folio_test_slab(folio)) {
free_large_kmalloc(folio, (void *)objp);
return;
}
debug_check_no_locks_freed(objp, c->object_size);
c = folio_slab(folio)->slab_cache;
local_irq_save(flags);
kfree_debugcheck(objp);
debug_check_no_locks_freed(objp, c->object_size);
debug_check_no_obj_freed(objp, c->object_size);
__cache_free(c, (void *)objp, _RET_IP_);
local_irq_restore(flags);
@ -4138,15 +4160,17 @@ void __check_heap_object(const void *ptr, unsigned long n,
size_t __ksize(const void *objp)
{
struct kmem_cache *c;
size_t size;
struct folio *folio;
BUG_ON(!objp);
if (unlikely(objp == ZERO_SIZE_PTR))
return 0;
c = virt_to_cache(objp);
size = c ? c->object_size : 0;
folio = virt_to_folio(objp);
if (!folio_test_slab(folio))
return folio_size(folio);
return size;
c = folio_slab(folio)->slab_cache;
return c->object_size;
}
EXPORT_SYMBOL(__ksize);

3
mm/slab.h
View File

@ -660,6 +660,9 @@ static inline struct kmem_cache *cache_from_obj(struct kmem_cache *s, void *x)
print_tracking(cachep, x);
return cachep;
}
void free_large_kmalloc(struct folio *folio, void *object);
#endif /* CONFIG_SLOB */
static inline size_t slab_ksize(const struct kmem_cache *s)

25
mm/slab_common.c
View File

@ -744,8 +744,8 @@ struct kmem_cache *kmalloc_slab(size_t size, gfp_t flags)
/*
* kmalloc_info[] is to make slub_debug=,kmalloc-xx option work at boot time.
* kmalloc_index() supports up to 2^25=32MB, so the final entry of the table is
* kmalloc-32M.
* kmalloc_index() supports up to 2^21=2MB, so the final entry of the table is
* kmalloc-2M.
*/
const struct kmalloc_info_struct kmalloc_info[] __initconst = {
INIT_KMALLOC_INFO(0, 0),
@ -769,11 +769,7 @@ const struct kmalloc_info_struct kmalloc_info[] __initconst = {
INIT_KMALLOC_INFO(262144, 256k),
INIT_KMALLOC_INFO(524288, 512k),
INIT_KMALLOC_INFO(1048576, 1M),
INIT_KMALLOC_INFO(2097152, 2M),
INIT_KMALLOC_INFO(4194304, 4M),
INIT_KMALLOC_INFO(8388608, 8M),
INIT_KMALLOC_INFO(16777216, 16M),
INIT_KMALLOC_INFO(33554432, 32M)
INIT_KMALLOC_INFO(2097152, 2M)
};
/*
@ -886,6 +882,21 @@ void __init create_kmalloc_caches(slab_flags_t flags)
/* Kmalloc array is now usable */
slab_state = UP;
}
void free_large_kmalloc(struct folio *folio, void *object)
{
unsigned int order = folio_order(folio);
if (WARN_ON_ONCE(order == 0))
pr_warn_once("object pointer: 0x%p\n", object);
kmemleak_free(object);
kasan_kfree_large(object);
mod_lruvec_page_state(folio_page(folio, 0), NR_SLAB_UNRECLAIMABLE_B,
-(PAGE_SIZE << order));
__free_pages(folio_page(folio, 0), order);
}
#endif /* !CONFIG_SLOB */
gfp_t kmalloc_fix_flags(gfp_t flags)

19
mm/slub.c
View File

@ -1704,12 +1704,6 @@ static bool freelist_corrupted(struct kmem_cache *s, struct slab *slab,
* Hooks for other subsystems that check memory allocations. In a typical
* production configuration these hooks all should produce no code at all.
*/
static __always_inline void kfree_hook(void *x)
{
kmemleak_free(x);
kasan_kfree_large(x);
}
static __always_inline bool slab_free_hook(struct kmem_cache *s,
void *x, bool init)
{
@ -3550,19 +3544,6 @@ struct detached_freelist {
struct kmem_cache *s;
};
static inline void free_large_kmalloc(struct folio *folio, void *object)
{
unsigned int order = folio_order(folio);
if (WARN_ON_ONCE(order == 0))
pr_warn_once("object pointer: 0x%p\n", object);
kfree_hook(object);
mod_lruvec_page_state(folio_page(folio, 0), NR_SLAB_UNRECLAIMABLE_B,
-(PAGE_SIZE << order));
__free_pages(folio_page(folio, 0), order);
}
/*
* This function progressively scans the array with free objects (with
* a limited look ahead) and extract objects belonging to the same