[PATCH 0/1] mm: Remove the SLAB allocator

[PATCH 0/1] mm: Remove the SLAB allocator

[Tobin C. Harding]

Recently a 2 year old bug was found in the SLAB allocator that crashes
the kernel.  This seems to imply that not that many people are using the
SLAB allocator.

Currently we have 3 slab allocators.  Two is company three is a crowd -
let's get rid of one. 

 - The SLUB allocator has been the default since 2.6.23
 - The SLOB allocator is kinda sexy.  Its only 664 LOC, the general
   design is outlined in KnR, and there is an optimisation taken from
   Knuth - say no more.

If you are using the SLAB allocator please speak now or forever hold your peace ...

Testing:

Build kernel with `make defconfig` (on x86_64 machine) followed by `make
kvmconfig`.  Then do the same and manually select SLOB.  Boot both
kernels in Qemu.


thanks,
Tobin.


Tobin C. Harding (1):
  mm: Remove SLAB allocator

 include/linux/slab.h |   26 -
 kernel/cpu.c         |    5 -
 mm/slab.c            | 4493 ------------------------------------------
 mm/slab.h            |   31 +-
 mm/slab_common.c     |   20 +-
 5 files changed, 5 insertions(+), 4570 deletions(-)
 delete mode 100644 mm/slab.c

-- 
2.21.0

[PATCH 1/1] mm: Remove SLAB allocator

[Tobin C. Harding]

We have SLOB for embedded devices and SLUB for everyone else.

Signed-off-by: Tobin C. Harding <tobin@kernel.org>
---
 include/linux/slab.h |   26 -
 kernel/cpu.c         |    5 -
 mm/slab.c            | 4493 ------------------------------------------
 mm/slab.h            |   31 +-
 mm/slab_common.c     |   20 +-
 5 files changed, 5 insertions(+), 4570 deletions(-)
 delete mode 100644 mm/slab.c

diff --git a/include/linux/slab.h b/include/linux/slab.h
index 9449b19c5f10..5b5e40ca2756 100644
--- a/include/linux/slab.h
+++ b/include/linux/slab.h
@@ -229,24 +229,6 @@ static inline void __check_heap_object(const void *ptr, unsigned long n,
  * Kmalloc array related definitions
  */
 
-#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.
- */
-#define KMALLOC_SHIFT_HIGH	((MAX_ORDER + PAGE_SHIFT - 1) <= 25 ? \
-				(MAX_ORDER + PAGE_SHIFT - 1) : 25)
-#define KMALLOC_SHIFT_MAX	KMALLOC_SHIFT_HIGH
-#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
@@ -756,12 +738,4 @@ static inline void *kzalloc_node(size_t size, gfp_t flags, int node)
 unsigned int kmem_cache_size(struct kmem_cache *s);
 void __init kmem_cache_init_late(void);
 
-#if defined(CONFIG_SMP) && defined(CONFIG_SLAB)
-int slab_prepare_cpu(unsigned int cpu);
-int slab_dead_cpu(unsigned int cpu);
-#else
-#define slab_prepare_cpu	NULL
-#define slab_dead_cpu		NULL
-#endif
-
 #endif	/* _LINUX_SLAB_H */
diff --git a/kernel/cpu.c b/kernel/cpu.c
index 6754f3ecfd94..223835ae0940 100644
--- a/kernel/cpu.c
+++ b/kernel/cpu.c
@@ -1378,11 +1378,6 @@ static struct cpuhp_step cpuhp_hp_states[] = {
 		.startup.single		= relay_prepare_cpu,
 		.teardown.single	= NULL,
 	},
-	[CPUHP_SLAB_PREPARE] = {
-		.name			= "slab:prepare",
-		.startup.single		= slab_prepare_cpu,
-		.teardown.single	= slab_dead_cpu,
-	},
 	[CPUHP_RCUTREE_PREP] = {
 		.name			= "RCU/tree:prepare",
 		.startup.single		= rcutree_prepare_cpu,
diff --git a/mm/slab.c b/mm/slab.c
deleted file mode 100644
index 329bfe67f2ca..000000000000
--- a/mm/slab.c
+++ /dev/null
@@ -1,4493 +0,0 @@
-// SPDX-License-Identifier: GPL-2.0
-/*
- * linux/mm/slab.c
- * Written by Mark Hemment, 1996/97.
- * (markhe@nextd.demon.co.uk)
- *
- * kmem_cache_destroy() + some cleanup - 1999 Andrea Arcangeli
- *
- * Major cleanup, different bufctl logic, per-cpu arrays
- *	(c) 2000 Manfred Spraul
- *
- * Cleanup, make the head arrays unconditional, preparation for NUMA
- * 	(c) 2002 Manfred Spraul
- *
- * An implementation of the Slab Allocator as described in outline in;
- *	UNIX Internals: The New Frontiers by Uresh Vahalia
- *	Pub: Prentice Hall	ISBN 0-13-101908-2
- * or with a little more detail in;
- *	The Slab Allocator: An Object-Caching Kernel Memory Allocator
- *	Jeff Bonwick (Sun Microsystems).
- *	Presented at: USENIX Summer 1994 Technical Conference
- *
- * The memory is organized in caches, one cache for each object type.
- * (e.g. inode_cache, dentry_cache, buffer_head, vm_area_struct)
- * Each cache consists out of many slabs (they are small (usually one
- * page long) and always contiguous), and each slab contains multiple
- * initialized objects.
- *
- * This means, that your constructor is used only for newly allocated
- * slabs and you must pass objects with the same initializations to
- * kmem_cache_free.
- *
- * Each cache can only support one memory type (GFP_DMA, GFP_HIGHMEM,
- * normal). If you need a special memory type, then must create a new
- * cache for that memory type.
- *
- * In order to reduce fragmentation, the slabs are sorted in 3 groups:
- *   full slabs with 0 free objects
- *   partial slabs
- *   empty slabs with no allocated objects
- *
- * If partial slabs exist, then new allocations come from these slabs,
- * otherwise from empty slabs or new slabs are allocated.
- *
- * kmem_cache_destroy() CAN CRASH if you try to allocate from the cache
- * during kmem_cache_destroy(). The caller must prevent concurrent allocs.
- *
- * Each cache has a short per-cpu head array, most allocs
- * and frees go into that array, and if that array overflows, then 1/2
- * of the entries in the array are given back into the global cache.
- * The head array is strictly LIFO and should improve the cache hit rates.
- * On SMP, it additionally reduces the spinlock operations.
- *
- * The c_cpuarray may not be read with enabled local interrupts -
- * it's changed with a smp_call_function().
- *
- * SMP synchronization:
- *  constructors and destructors are called without any locking.
- *  Several members in struct kmem_cache and struct slab never change, they
- *	are accessed without any locking.
- *  The per-cpu arrays are never accessed from the wrong cpu, no locking,
- *  	and local interrupts are disabled so slab code is preempt-safe.
- *  The non-constant members are protected with a per-cache irq spinlock.
- *
- * Many thanks to Mark Hemment, who wrote another per-cpu slab patch
- * in 2000 - many ideas in the current implementation are derived from
- * his patch.
- *
- * Further notes from the original documentation:
- *
- * 11 April '97.  Started multi-threading - markhe
- *	The global cache-chain is protected by the mutex 'slab_mutex'.
- *	The sem is only needed when accessing/extending the cache-chain, which
- *	can never happen inside an interrupt (kmem_cache_create(),
- *	kmem_cache_shrink() and kmem_cache_reap()).
- *
- *	At present, each engine can be growing a cache.  This should be blocked.
- *
- * 15 March 2005. NUMA slab allocator.
- *	Shai Fultheim <shai@scalex86.org>.
- *	Shobhit Dayal <shobhit@calsoftinc.com>
- *	Alok N Kataria <alokk@calsoftinc.com>
- *	Christoph Lameter <christoph@lameter.com>
- *
- *	Modified the slab allocator to be node aware on NUMA systems.
- *	Each node has its own list of partial, free and full slabs.
- *	All object allocations for a node occur from node specific slab lists.
- */
-
-#include	<linux/slab.h>
-#include	<linux/mm.h>
-#include	<linux/poison.h>
-#include	<linux/swap.h>
-#include	<linux/cache.h>
-#include	<linux/interrupt.h>
-#include	<linux/init.h>
-#include	<linux/compiler.h>
-#include	<linux/cpuset.h>
-#include	<linux/proc_fs.h>
-#include	<linux/seq_file.h>
-#include	<linux/notifier.h>
-#include	<linux/kallsyms.h>
-#include	<linux/cpu.h>
-#include	<linux/sysctl.h>
-#include	<linux/module.h>
-#include	<linux/rcupdate.h>
-#include	<linux/string.h>
-#include	<linux/uaccess.h>
-#include	<linux/nodemask.h>
-#include	<linux/kmemleak.h>
-#include	<linux/mempolicy.h>
-#include	<linux/mutex.h>
-#include	<linux/fault-inject.h>
-#include	<linux/rtmutex.h>
-#include	<linux/reciprocal_div.h>
-#include	<linux/debugobjects.h>
-#include	<linux/memory.h>
-#include	<linux/prefetch.h>
-#include	<linux/sched/task_stack.h>
-
-#include	<net/sock.h>
-
-#include	<asm/cacheflush.h>
-#include	<asm/tlbflush.h>
-#include	<asm/page.h>
-
-#include <trace/events/kmem.h>
-
-#include	"internal.h"
-
-#include	"slab.h"
-
-/*
- * DEBUG	- 1 for kmem_cache_create() to honour; SLAB_RED_ZONE & SLAB_POISON.
- *		  0 for faster, smaller code (especially in the critical paths).
- *
- * STATS	- 1 to collect stats for /proc/slabinfo.
- *		  0 for faster, smaller code (especially in the critical paths).
- *
- * FORCED_DEBUG	- 1 enables SLAB_RED_ZONE and SLAB_POISON (if possible)
- */
-
-#ifdef CONFIG_DEBUG_SLAB
-#define	DEBUG		1
-#define	STATS		1
-#define	FORCED_DEBUG	1
-#else
-#define	DEBUG		0
-#define	STATS		0
-#define	FORCED_DEBUG	0
-#endif
-
-/* Shouldn't this be in a header file somewhere? */
-#define	BYTES_PER_WORD		sizeof(void *)
-#define	REDZONE_ALIGN		max(BYTES_PER_WORD, __alignof__(unsigned long long))
-
-#ifndef ARCH_KMALLOC_FLAGS
-#define ARCH_KMALLOC_FLAGS SLAB_HWCACHE_ALIGN
-#endif
-
-#define FREELIST_BYTE_INDEX (((PAGE_SIZE >> BITS_PER_BYTE) \
-				<= SLAB_OBJ_MIN_SIZE) ? 1 : 0)
-
-#if FREELIST_BYTE_INDEX
-typedef unsigned char freelist_idx_t;
-#else
-typedef unsigned short freelist_idx_t;
-#endif
-
-#define SLAB_OBJ_MAX_NUM ((1 << sizeof(freelist_idx_t) * BITS_PER_BYTE) - 1)
-
-/*
- * struct array_cache
- *
- * Purpose:
- * - LIFO ordering, to hand out cache-warm objects from _alloc
- * - reduce the number of linked list operations
- * - reduce spinlock operations
- *
- * The limit is stored in the per-cpu structure to reduce the data cache
- * footprint.
- *
- */
-struct array_cache {
-	unsigned int avail;
-	unsigned int limit;
-	unsigned int batchcount;
-	unsigned int touched;
-	void *entry[];	/*
-			 * Must have this definition in here for the proper
-			 * alignment of array_cache. Also simplifies accessing
-			 * the entries.
-			 */
-};
-
-struct alien_cache {
-	spinlock_t lock;
-	struct array_cache ac;
-};
-
-/*
- * Need this for bootstrapping a per node allocator.
- */
-#define NUM_INIT_LISTS (2 * MAX_NUMNODES)
-static struct kmem_cache_node __initdata init_kmem_cache_node[NUM_INIT_LISTS];
-#define	CACHE_CACHE 0
-#define	SIZE_NODE (MAX_NUMNODES)
-
-static int drain_freelist(struct kmem_cache *cache,
-			struct kmem_cache_node *n, int tofree);
-static void free_block(struct kmem_cache *cachep, void **objpp, int len,
-			int node, struct list_head *list);
-static void slabs_destroy(struct kmem_cache *cachep, struct list_head *list);
-static int enable_cpucache(struct kmem_cache *cachep, gfp_t gfp);
-static void cache_reap(struct work_struct *unused);
-
-static inline void fixup_objfreelist_debug(struct kmem_cache *cachep,
-						void **list);
-static inline void fixup_slab_list(struct kmem_cache *cachep,
-				struct kmem_cache_node *n, struct page *page,
-				void **list);
-static int slab_early_init = 1;
-
-#define INDEX_NODE kmalloc_index(sizeof(struct kmem_cache_node))
-
-static void kmem_cache_node_init(struct kmem_cache_node *parent)
-{
-	INIT_LIST_HEAD(&parent->slabs_full);
-	INIT_LIST_HEAD(&parent->slabs_partial);
-	INIT_LIST_HEAD(&parent->slabs_free);
-	parent->total_slabs = 0;
-	parent->free_slabs = 0;
-	parent->shared = NULL;
-	parent->alien = NULL;
-	parent->colour_next = 0;
-	spin_lock_init(&parent->list_lock);
-	parent->free_objects = 0;
-	parent->free_touched = 0;
-}
-
-#define MAKE_LIST(cachep, listp, slab, nodeid)				\
-	do {								\
-		INIT_LIST_HEAD(listp);					\
-		list_splice(&get_node(cachep, nodeid)->slab, listp);	\
-	} while (0)
-
-#define	MAKE_ALL_LISTS(cachep, ptr, nodeid)				\
-	do {								\
-	MAKE_LIST((cachep), (&(ptr)->slabs_full), slabs_full, nodeid);	\
-	MAKE_LIST((cachep), (&(ptr)->slabs_partial), slabs_partial, nodeid); \
-	MAKE_LIST((cachep), (&(ptr)->slabs_free), slabs_free, nodeid);	\
-	} while (0)
-
-#define CFLGS_OBJFREELIST_SLAB	((slab_flags_t __force)0x40000000U)
-#define CFLGS_OFF_SLAB		((slab_flags_t __force)0x80000000U)
-#define	OBJFREELIST_SLAB(x)	((x)->flags & CFLGS_OBJFREELIST_SLAB)
-#define	OFF_SLAB(x)	((x)->flags & CFLGS_OFF_SLAB)
-
-#define BATCHREFILL_LIMIT	16
-/*
- * Optimization question: fewer reaps means less probability for unnessary
- * cpucache drain/refill cycles.
- *
- * OTOH the cpuarrays can contain lots of objects,
- * which could lock up otherwise freeable slabs.
- */
-#define REAPTIMEOUT_AC		(2*HZ)
-#define REAPTIMEOUT_NODE	(4*HZ)
-
-#if STATS
-#define	STATS_INC_ACTIVE(x)	((x)->num_active++)
-#define	STATS_DEC_ACTIVE(x)	((x)->num_active--)
-#define	STATS_INC_ALLOCED(x)	((x)->num_allocations++)
-#define	STATS_INC_GROWN(x)	((x)->grown++)
-#define	STATS_ADD_REAPED(x,y)	((x)->reaped += (y))
-#define	STATS_SET_HIGH(x)						\
-	do {								\
-		if ((x)->num_active > (x)->high_mark)			\
-			(x)->high_mark = (x)->num_active;		\
-	} while (0)
-#define	STATS_INC_ERR(x)	((x)->errors++)
-#define	STATS_INC_NODEALLOCS(x)	((x)->node_allocs++)
-#define	STATS_INC_NODEFREES(x)	((x)->node_frees++)
-#define STATS_INC_ACOVERFLOW(x)   ((x)->node_overflow++)
-#define	STATS_SET_FREEABLE(x, i)					\
-	do {								\
-		if ((x)->max_freeable < i)				\
-			(x)->max_freeable = i;				\
-	} while (0)
-#define STATS_INC_ALLOCHIT(x)	atomic_inc(&(x)->allochit)
-#define STATS_INC_ALLOCMISS(x)	atomic_inc(&(x)->allocmiss)
-#define STATS_INC_FREEHIT(x)	atomic_inc(&(x)->freehit)
-#define STATS_INC_FREEMISS(x)	atomic_inc(&(x)->freemiss)
-#else
-#define	STATS_INC_ACTIVE(x)	do { } while (0)
-#define	STATS_DEC_ACTIVE(x)	do { } while (0)
-#define	STATS_INC_ALLOCED(x)	do { } while (0)
-#define	STATS_INC_GROWN(x)	do { } while (0)
-#define	STATS_ADD_REAPED(x,y)	do { (void)(y); } while (0)
-#define	STATS_SET_HIGH(x)	do { } while (0)
-#define	STATS_INC_ERR(x)	do { } while (0)
-#define	STATS_INC_NODEALLOCS(x)	do { } while (0)
-#define	STATS_INC_NODEFREES(x)	do { } while (0)
-#define STATS_INC_ACOVERFLOW(x)   do { } while (0)
-#define	STATS_SET_FREEABLE(x, i) do { } while (0)
-#define STATS_INC_ALLOCHIT(x)	do { } while (0)
-#define STATS_INC_ALLOCMISS(x)	do { } while (0)
-#define STATS_INC_FREEHIT(x)	do { } while (0)
-#define STATS_INC_FREEMISS(x)	do { } while (0)
-#endif
-
-#if DEBUG
-
-/*
- * memory layout of objects:
- * 0		: objp
- * 0 .. cachep->obj_offset - BYTES_PER_WORD - 1: padding. This ensures that
- * 		the end of an object is aligned with the end of the real
- * 		allocation. Catches writes behind the end of the allocation.
- * cachep->obj_offset - BYTES_PER_WORD .. cachep->obj_offset - 1:
- * 		redzone word.
- * cachep->obj_offset: The real object.
- * cachep->size - 2* BYTES_PER_WORD: redzone word [BYTES_PER_WORD long]
- * cachep->size - 1* BYTES_PER_WORD: last caller address
- *					[BYTES_PER_WORD long]
- */
-static int obj_offset(struct kmem_cache *cachep)
-{
-	return cachep->obj_offset;
-}
-
-static unsigned long long *dbg_redzone1(struct kmem_cache *cachep, void *objp)
-{
-	BUG_ON(!(cachep->flags & SLAB_RED_ZONE));
-	return (unsigned long long*) (objp + obj_offset(cachep) -
-				      sizeof(unsigned long long));
-}
-
-static unsigned long long *dbg_redzone2(struct kmem_cache *cachep, void *objp)
-{
-	BUG_ON(!(cachep->flags & SLAB_RED_ZONE));
-	if (cachep->flags & SLAB_STORE_USER)
-		return (unsigned long long *)(objp + cachep->size -
-					      sizeof(unsigned long long) -
-					      REDZONE_ALIGN);
-	return (unsigned long long *) (objp + cachep->size -
-				       sizeof(unsigned long long));
-}
-
-static void **dbg_userword(struct kmem_cache *cachep, void *objp)
-{
-	BUG_ON(!(cachep->flags & SLAB_STORE_USER));
-	return (void **)(objp + cachep->size - BYTES_PER_WORD);
-}
-
-#else
-
-#define obj_offset(x)			0
-#define dbg_redzone1(cachep, objp)	({BUG(); (unsigned long long *)NULL;})
-#define dbg_redzone2(cachep, objp)	({BUG(); (unsigned long long *)NULL;})
-#define dbg_userword(cachep, objp)	({BUG(); (void **)NULL;})
-
-#endif
-
-#ifdef CONFIG_DEBUG_SLAB_LEAK
-
-static inline bool is_store_user_clean(struct kmem_cache *cachep)
-{
-	return atomic_read(&cachep->store_user_clean) == 1;
-}
-
-static inline void set_store_user_clean(struct kmem_cache *cachep)
-{
-	atomic_set(&cachep->store_user_clean, 1);
-}
-
-static inline void set_store_user_dirty(struct kmem_cache *cachep)
-{
-	if (is_store_user_clean(cachep))
-		atomic_set(&cachep->store_user_clean, 0);
-}
-
-#else
-static inline void set_store_user_dirty(struct kmem_cache *cachep) {}
-
-#endif
-
-/*
- * Do not go above this order unless 0 objects fit into the slab or
- * overridden on the command line.
- */
-#define	SLAB_MAX_ORDER_HI	1
-#define	SLAB_MAX_ORDER_LO	0
-static int slab_max_order = SLAB_MAX_ORDER_LO;
-static bool slab_max_order_set __initdata;
-
-static inline struct kmem_cache *virt_to_cache(const void *obj)
-{
-	struct page *page = virt_to_head_page(obj);
-	return page->slab_cache;
-}
-
-static inline void *index_to_obj(struct kmem_cache *cache, struct page *page,
-				 unsigned int idx)
-{
-	return page->s_mem + cache->size * idx;
-}
-
-#define BOOT_CPUCACHE_ENTRIES	1
-/* internal cache of cache description objs */
-static struct kmem_cache kmem_cache_boot = {
-	.batchcount = 1,
-	.limit = BOOT_CPUCACHE_ENTRIES,
-	.shared = 1,
-	.size = sizeof(struct kmem_cache),
-	.name = "kmem_cache",
-};
-
-static DEFINE_PER_CPU(struct delayed_work, slab_reap_work);
-
-static inline struct array_cache *cpu_cache_get(struct kmem_cache *cachep)
-{
-	return this_cpu_ptr(cachep->cpu_cache);
-}
-
-/*
- * Calculate the number of objects and left-over bytes for a given buffer size.
- */
-static unsigned int cache_estimate(unsigned long gfporder, size_t buffer_size,
-		slab_flags_t flags, size_t *left_over)
-{
-	unsigned int num;
-	size_t slab_size = PAGE_SIZE << gfporder;
-
-	/*
-	 * The slab management structure can be either off the slab or
-	 * on it. For the latter case, the memory allocated for a
-	 * slab is used for:
-	 *
-	 * - @buffer_size bytes for each object
-	 * - One freelist_idx_t for each object
-	 *
-	 * We don't need to consider alignment of freelist because
-	 * freelist will be at the end of slab page. The objects will be
-	 * at the correct alignment.
-	 *
-	 * If the slab management structure is off the slab, then the
-	 * alignment will already be calculated into the size. Because
-	 * the slabs are all pages aligned, the objects will be at the
-	 * correct alignment when allocated.
-	 */
-	if (flags & (CFLGS_OBJFREELIST_SLAB | CFLGS_OFF_SLAB)) {
-		num = slab_size / buffer_size;
-		*left_over = slab_size % buffer_size;
-	} else {
-		num = slab_size / (buffer_size + sizeof(freelist_idx_t));
-		*left_over = slab_size %
-			(buffer_size + sizeof(freelist_idx_t));
-	}
-
-	return num;
-}
-
-#if DEBUG
-#define slab_error(cachep, msg) __slab_error(__func__, cachep, msg)
-
-static void __slab_error(const char *function, struct kmem_cache *cachep,
-			char *msg)
-{
-	pr_err("slab error in %s(): cache `%s': %s\n",
-	       function, cachep->name, msg);
-	dump_stack();
-	add_taint(TAINT_BAD_PAGE, LOCKDEP_NOW_UNRELIABLE);
-}
-#endif
-
-/*
- * By default on NUMA we use alien caches to stage the freeing of
- * objects allocated from other nodes. This causes massive memory
- * inefficiencies when using fake NUMA setup to split memory into a
- * large number of small nodes, so it can be disabled on the command
- * line
-  */
-
-static int use_alien_caches __read_mostly = 1;
-static int __init noaliencache_setup(char *s)
-{
-	use_alien_caches = 0;
-	return 1;
-}
-__setup("noaliencache", noaliencache_setup);
-
-static int __init slab_max_order_setup(char *str)
-{
-	get_option(&str, &slab_max_order);
-	slab_max_order = slab_max_order < 0 ? 0 :
-				min(slab_max_order, MAX_ORDER - 1);
-	slab_max_order_set = true;
-
-	return 1;
-}
-__setup("slab_max_order=", slab_max_order_setup);
-
-#ifdef CONFIG_NUMA
-/*
- * Special reaping functions for NUMA systems called from cache_reap().
- * These take care of doing round robin flushing of alien caches (containing
- * objects freed on different nodes from which they were allocated) and the
- * flushing of remote pcps by calling drain_node_pages.
- */
-static DEFINE_PER_CPU(unsigned long, slab_reap_node);
-
-static void init_reap_node(int cpu)
-{
-	per_cpu(slab_reap_node, cpu) = next_node_in(cpu_to_mem(cpu),
-						    node_online_map);
-}
-
-static void next_reap_node(void)
-{
-	int node = __this_cpu_read(slab_reap_node);
-
-	node = next_node_in(node, node_online_map);
-	__this_cpu_write(slab_reap_node, node);
-}
-
-#else
-#define init_reap_node(cpu) do { } while (0)
-#define next_reap_node(void) do { } while (0)
-#endif
-
-/*
- * Initiate the reap timer running on the target CPU.  We run at around 1 to 2Hz
- * via the workqueue/eventd.
- * Add the CPU number into the expiration time to minimize the possibility of
- * the CPUs getting into lockstep and contending for the global cache chain
- * lock.
- */
-static void start_cpu_timer(int cpu)
-{
-	struct delayed_work *reap_work = &per_cpu(slab_reap_work, cpu);
-
-	if (reap_work->work.func == NULL) {
-		init_reap_node(cpu);
-		INIT_DEFERRABLE_WORK(reap_work, cache_reap);
-		schedule_delayed_work_on(cpu, reap_work,
-					__round_jiffies_relative(HZ, cpu));
-	}
-}
-
-static void init_arraycache(struct array_cache *ac, int limit, int batch)
-{
-	if (ac) {
-		ac->avail = 0;
-		ac->limit = limit;
-		ac->batchcount = batch;
-		ac->touched = 0;
-	}
-}
-
-static struct array_cache *alloc_arraycache(int node, int entries,
-					    int batchcount, gfp_t gfp)
-{
-	size_t memsize = sizeof(void *) * entries + sizeof(struct array_cache);
-	struct array_cache *ac = NULL;
-
-	ac = kmalloc_node(memsize, gfp, node);
-	/*
-	 * The array_cache structures contain pointers to free object.
-	 * However, when such objects are allocated or transferred to another
-	 * cache the pointers are not cleared and they could be counted as
-	 * valid references during a kmemleak scan. Therefore, kmemleak must
-	 * not scan such objects.
-	 */
-	kmemleak_no_scan(ac);
-	init_arraycache(ac, entries, batchcount);
-	return ac;
-}
-
-static noinline void cache_free_pfmemalloc(struct kmem_cache *cachep,
-					struct page *page, void *objp)
-{
-	struct kmem_cache_node *n;
-	int page_node;
-	LIST_HEAD(list);
-
-	page_node = page_to_nid(page);
-	n = get_node(cachep, page_node);
-
-	spin_lock(&n->list_lock);
-	free_block(cachep, &objp, 1, page_node, &list);
-	spin_unlock(&n->list_lock);
-
-	slabs_destroy(cachep, &list);
-}
-
-/*
- * Transfer objects in one arraycache to another.
- * Locking must be handled by the caller.
- *
- * Return the number of entries transferred.
- */
-static int transfer_objects(struct array_cache *to,
-		struct array_cache *from, unsigned int max)
-{
-	/* Figure out how many entries to transfer */
-	int nr = min3(from->avail, max, to->limit - to->avail);
-
-	if (!nr)
-		return 0;
-
-	memcpy(to->entry + to->avail, from->entry + from->avail -nr,
-			sizeof(void *) *nr);
-
-	from->avail -= nr;
-	to->avail += nr;
-	return nr;
-}
-
-#ifndef CONFIG_NUMA
-
-#define drain_alien_cache(cachep, alien) do { } while (0)
-#define reap_alien(cachep, n) do { } while (0)
-
-static inline struct alien_cache **alloc_alien_cache(int node,
-						int limit, gfp_t gfp)
-{
-	return NULL;
-}
-
-static inline void free_alien_cache(struct alien_cache **ac_ptr)
-{
-}
-
-static inline int cache_free_alien(struct kmem_cache *cachep, void *objp)
-{
-	return 0;
-}
-
-static inline void *alternate_node_alloc(struct kmem_cache *cachep,
-		gfp_t flags)
-{
-	return NULL;
-}
-
-static inline void *____cache_alloc_node(struct kmem_cache *cachep,
-		 gfp_t flags, int nodeid)
-{
-	return NULL;
-}
-
-static inline gfp_t gfp_exact_node(gfp_t flags)
-{
-	return flags & ~__GFP_NOFAIL;
-}
-
-#else	/* CONFIG_NUMA */
-
-static void *____cache_alloc_node(struct kmem_cache *, gfp_t, int);
-static void *alternate_node_alloc(struct kmem_cache *, gfp_t);
-
-static struct alien_cache *__alloc_alien_cache(int node, int entries,
-						int batch, gfp_t gfp)
-{
-	size_t memsize = sizeof(void *) * entries + sizeof(struct alien_cache);
-	struct alien_cache *alc = NULL;
-
-	alc = kmalloc_node(memsize, gfp, node);
-	if (alc) {
-		kmemleak_no_scan(alc);
-		init_arraycache(&alc->ac, entries, batch);
-		spin_lock_init(&alc->lock);
-	}
-	return alc;
-}
-
-static struct alien_cache **alloc_alien_cache(int node, int limit, gfp_t gfp)
-{
-	struct alien_cache **alc_ptr;
-	int i;
-
-	if (limit > 1)
-		limit = 12;
-	alc_ptr = kcalloc_node(nr_node_ids, sizeof(void *), gfp, node);
-	if (!alc_ptr)
-		return NULL;
-
-	for_each_node(i) {
-		if (i == node || !node_online(i))
-			continue;
-		alc_ptr[i] = __alloc_alien_cache(node, limit, 0xbaadf00d, gfp);
-		if (!alc_ptr[i]) {
-			for (i--; i >= 0; i--)
-				kfree(alc_ptr[i]);
-			kfree(alc_ptr);
-			return NULL;
-		}
-	}
-	return alc_ptr;
-}
-
-static void free_alien_cache(struct alien_cache **alc_ptr)
-{
-	int i;
-
-	if (!alc_ptr)
-		return;
-	for_each_node(i)
-	    kfree(alc_ptr[i]);
-	kfree(alc_ptr);
-}
-
-static void __drain_alien_cache(struct kmem_cache *cachep,
-				struct array_cache *ac, int node,
-				struct list_head *list)
-{
-	struct kmem_cache_node *n = get_node(cachep, node);
-
-	if (ac->avail) {
-		spin_lock(&n->list_lock);
-		/*
-		 * Stuff objects into the remote nodes shared array first.
-		 * That way we could avoid the overhead of putting the objects
-		 * into the free lists and getting them back later.
-		 */
-		if (n->shared)
-			transfer_objects(n->shared, ac, ac->limit);
-
-		free_block(cachep, ac->entry, ac->avail, node, list);
-		ac->avail = 0;
-		spin_unlock(&n->list_lock);
-	}
-}
-
-/*
- * Called from cache_reap() to regularly drain alien caches round robin.
- */
-static void reap_alien(struct kmem_cache *cachep, struct kmem_cache_node *n)
-{
-	int node = __this_cpu_read(slab_reap_node);
-
-	if (n->alien) {
-		struct alien_cache *alc = n->alien[node];
-		struct array_cache *ac;
-
-		if (alc) {
-			ac = &alc->ac;
-			if (ac->avail && spin_trylock_irq(&alc->lock)) {
-				LIST_HEAD(list);
-
-				__drain_alien_cache(cachep, ac, node, &list);
-				spin_unlock_irq(&alc->lock);
-				slabs_destroy(cachep, &list);
-			}
-		}
-	}
-}
-
-static void drain_alien_cache(struct kmem_cache *cachep,
-				struct alien_cache **alien)
-{
-	int i = 0;
-	struct alien_cache *alc;
-	struct array_cache *ac;
-	unsigned long flags;
-
-	for_each_online_node(i) {
-		alc = alien[i];
-		if (alc) {
-			LIST_HEAD(list);
-
-			ac = &alc->ac;
-			spin_lock_irqsave(&alc->lock, flags);
-			__drain_alien_cache(cachep, ac, i, &list);
-			spin_unlock_irqrestore(&alc->lock, flags);
-			slabs_destroy(cachep, &list);
-		}
-	}
-}
-
-static int __cache_free_alien(struct kmem_cache *cachep, void *objp,
-				int node, int page_node)
-{
-	struct kmem_cache_node *n;
-	struct alien_cache *alien = NULL;
-	struct array_cache *ac;
-	LIST_HEAD(list);
-
-	n = get_node(cachep, node);
-	STATS_INC_NODEFREES(cachep);
-	if (n->alien && n->alien[page_node]) {
-		alien = n->alien[page_node];
-		ac = &alien->ac;
-		spin_lock(&alien->lock);
-		if (unlikely(ac->avail == ac->limit)) {
-			STATS_INC_ACOVERFLOW(cachep);
-			__drain_alien_cache(cachep, ac, page_node, &list);
-		}
-		ac->entry[ac->avail++] = objp;
-		spin_unlock(&alien->lock);
-		slabs_destroy(cachep, &list);
-	} else {
-		n = get_node(cachep, page_node);
-		spin_lock(&n->list_lock);
-		free_block(cachep, &objp, 1, page_node, &list);
-		spin_unlock(&n->list_lock);
-		slabs_destroy(cachep, &list);
-	}
-	return 1;
-}
-
-static inline int cache_free_alien(struct kmem_cache *cachep, void *objp)
-{
-	int page_node = page_to_nid(virt_to_page(objp));
-	int node = numa_mem_id();
-	/*
-	 * Make sure we are not freeing a object from another node to the array
-	 * cache on this cpu.
-	 */
-	if (likely(node == page_node))
-		return 0;
-
-	return __cache_free_alien(cachep, objp, node, page_node);
-}
-
-/*
- * Construct gfp mask to allocate from a specific node but do not reclaim or
- * warn about failures.
- */
-static inline gfp_t gfp_exact_node(gfp_t flags)
-{
-	return (flags | __GFP_THISNODE | __GFP_NOWARN) & ~(__GFP_RECLAIM|__GFP_NOFAIL);
-}
-#endif
-
-static int init_cache_node(struct kmem_cache *cachep, int node, gfp_t gfp)
-{
-	struct kmem_cache_node *n;
-
-	/*
-	 * Set up the kmem_cache_node for cpu before we can
-	 * begin anything. Make sure some other cpu on this
-	 * node has not already allocated this
-	 */
-	n = get_node(cachep, node);
-	if (n) {
-		spin_lock_irq(&n->list_lock);
-		n->free_limit = (1 + nr_cpus_node(node)) * cachep->batchcount +
-				cachep->num;
-		spin_unlock_irq(&n->list_lock);
-
-		return 0;
-	}
-
-	n = kmalloc_node(sizeof(struct kmem_cache_node), gfp, node);
-	if (!n)
-		return -ENOMEM;
-
-	kmem_cache_node_init(n);
-	n->next_reap = jiffies + REAPTIMEOUT_NODE +
-		    ((unsigned long)cachep) % REAPTIMEOUT_NODE;
-
-	n->free_limit =
-		(1 + nr_cpus_node(node)) * cachep->batchcount + cachep->num;
-
-	/*
-	 * The kmem_cache_nodes don't come and go as CPUs
-	 * come and go.  slab_mutex is sufficient
-	 * protection here.
-	 */
-	cachep->node[node] = n;
-
-	return 0;
-}
-
-#if (defined(CONFIG_NUMA) && defined(CONFIG_MEMORY_HOTPLUG)) || defined(CONFIG_SMP)
-/*
- * Allocates and initializes node for a node on each slab cache, used for
- * either memory or cpu hotplug.  If memory is being hot-added, the kmem_cache_node
- * will be allocated off-node since memory is not yet online for the new node.
- * When hotplugging memory or a cpu, existing node are not replaced if
- * already in use.
- *
- * Must hold slab_mutex.
- */
-static int init_cache_node_node(int node)
-{
-	int ret;
-	struct kmem_cache *cachep;
-
-	list_for_each_entry(cachep, &slab_caches, list) {
-		ret = init_cache_node(cachep, node, GFP_KERNEL);
-		if (ret)
-			return ret;
-	}
-
-	return 0;
-}
-#endif
-
-static int setup_kmem_cache_node(struct kmem_cache *cachep,
-				int node, gfp_t gfp, bool force_change)
-{
-	int ret = -ENOMEM;
-	struct kmem_cache_node *n;
-	struct array_cache *old_shared = NULL;
-	struct array_cache *new_shared = NULL;
-	struct alien_cache **new_alien = NULL;
-	LIST_HEAD(list);
-
-	if (use_alien_caches) {
-		new_alien = alloc_alien_cache(node, cachep->limit, gfp);
-		if (!new_alien)
-			goto fail;
-	}
-
-	if (cachep->shared) {
-		new_shared = alloc_arraycache(node,
-			cachep->shared * cachep->batchcount, 0xbaadf00d, gfp);
-		if (!new_shared)
-			goto fail;
-	}
-
-	ret = init_cache_node(cachep, node, gfp);
-	if (ret)
-		goto fail;
-
-	n = get_node(cachep, node);
-	spin_lock_irq(&n->list_lock);
-	if (n->shared && force_change) {
-		free_block(cachep, n->shared->entry,
-				n->shared->avail, node, &list);
-		n->shared->avail = 0;
-	}
-
-	if (!n->shared || force_change) {
-		old_shared = n->shared;
-		n->shared = new_shared;
-		new_shared = NULL;
-	}
-
-	if (!n->alien) {
-		n->alien = new_alien;
-		new_alien = NULL;
-	}
-
-	spin_unlock_irq(&n->list_lock);
-	slabs_destroy(cachep, &list);
-
-	/*
-	 * To protect lockless access to n->shared during irq disabled context.
-	 * If n->shared isn't NULL in irq disabled context, accessing to it is
-	 * guaranteed to be valid until irq is re-enabled, because it will be
-	 * freed after synchronize_rcu().
-	 */
-	if (old_shared && force_change)
-		synchronize_rcu();
-
-fail:
-	kfree(old_shared);
-	kfree(new_shared);
-	free_alien_cache(new_alien);
-
-	return ret;
-}
-
-#ifdef CONFIG_SMP
-
-static void cpuup_canceled(long cpu)
-{
-	struct kmem_cache *cachep;
-	struct kmem_cache_node *n = NULL;
-	int node = cpu_to_mem(cpu);
-	const struct cpumask *mask = cpumask_of_node(node);
-
-	list_for_each_entry(cachep, &slab_caches, list) {
-		struct array_cache *nc;
-		struct array_cache *shared;
-		struct alien_cache **alien;
-		LIST_HEAD(list);
-
-		n = get_node(cachep, node);
-		if (!n)
-			continue;
-
-		spin_lock_irq(&n->list_lock);
-
-		/* Free limit for this kmem_cache_node */
-		n->free_limit -= cachep->batchcount;
-
-		/* cpu is dead; no one can alloc from it. */
-		nc = per_cpu_ptr(cachep->cpu_cache, cpu);
-		if (nc) {
-			free_block(cachep, nc->entry, nc->avail, node, &list);
-			nc->avail = 0;
-		}
-
-		if (!cpumask_empty(mask)) {
-			spin_unlock_irq(&n->list_lock);
-			goto free_slab;
-		}
-
-		shared = n->shared;
-		if (shared) {
-			free_block(cachep, shared->entry,
-				   shared->avail, node, &list);
-			n->shared = NULL;
-		}
-
-		alien = n->alien;
-		n->alien = NULL;
-
-		spin_unlock_irq(&n->list_lock);
-
-		kfree(shared);
-		if (alien) {
-			drain_alien_cache(cachep, alien);
-			free_alien_cache(alien);
-		}
-
-free_slab:
-		slabs_destroy(cachep, &list);
-	}
-	/*
-	 * In the previous loop, all the objects were freed to
-	 * the respective cache's slabs,  now we can go ahead and
-	 * shrink each nodelist to its limit.
-	 */
-	list_for_each_entry(cachep, &slab_caches, list) {
-		n = get_node(cachep, node);
-		if (!n)
-			continue;
-		drain_freelist(cachep, n, INT_MAX);
-	}
-}
-
-static int cpuup_prepare(long cpu)
-{
-	struct kmem_cache *cachep;
-	int node = cpu_to_mem(cpu);
-	int err;
-
-	/*
-	 * We need to do this right in the beginning since
-	 * alloc_arraycache's are going to use this list.
-	 * kmalloc_node allows us to add the slab to the right
-	 * kmem_cache_node and not this cpu's kmem_cache_node
-	 */
-	err = init_cache_node_node(node);
-	if (err < 0)
-		goto bad;
-
-	/*
-	 * Now we can go ahead with allocating the shared arrays and
-	 * array caches
-	 */
-	list_for_each_entry(cachep, &slab_caches, list) {
-		err = setup_kmem_cache_node(cachep, node, GFP_KERNEL, false);
-		if (err)
-			goto bad;
-	}
-
-	return 0;
-bad:
-	cpuup_canceled(cpu);
-	return -ENOMEM;
-}
-
-int slab_prepare_cpu(unsigned int cpu)
-{
-	int err;
-
-	mutex_lock(&slab_mutex);
-	err = cpuup_prepare(cpu);
-	mutex_unlock(&slab_mutex);
-	return err;
-}
-
-/*
- * This is called for a failed online attempt and for a successful
- * offline.
- *
- * Even if all the cpus of a node are down, we don't free the
- * kmem_list3 of any cache. This to avoid a race between cpu_down, and
- * a kmalloc allocation from another cpu for memory from the node of
- * the cpu going down.  The list3 structure is usually allocated from
- * kmem_cache_create() and gets destroyed at kmem_cache_destroy().
- */
-int slab_dead_cpu(unsigned int cpu)
-{
-	mutex_lock(&slab_mutex);
-	cpuup_canceled(cpu);
-	mutex_unlock(&slab_mutex);
-	return 0;
-}
-#endif
-
-static int slab_online_cpu(unsigned int cpu)
-{
-	start_cpu_timer(cpu);
-	return 0;
-}
-
-static int slab_offline_cpu(unsigned int cpu)
-{
-	/*
-	 * Shutdown cache reaper. Note that the slab_mutex is held so
-	 * that if cache_reap() is invoked it cannot do anything
-	 * expensive but will only modify reap_work and reschedule the
-	 * timer.
-	 */
-	cancel_delayed_work_sync(&per_cpu(slab_reap_work, cpu));
-	/* Now the cache_reaper is guaranteed to be not running. */
-	per_cpu(slab_reap_work, cpu).work.func = NULL;
-	return 0;
-}
-
-#if defined(CONFIG_NUMA) && defined(CONFIG_MEMORY_HOTPLUG)
-/*
- * Drains freelist for a node on each slab cache, used for memory hot-remove.
- * Returns -EBUSY if all objects cannot be drained so that the node is not
- * removed.
- *
- * Must hold slab_mutex.
- */
-static int __meminit drain_cache_node_node(int node)
-{
-	struct kmem_cache *cachep;
-	int ret = 0;
-
-	list_for_each_entry(cachep, &slab_caches, list) {
-		struct kmem_cache_node *n;
-
-		n = get_node(cachep, node);
-		if (!n)
-			continue;
-
-		drain_freelist(cachep, n, INT_MAX);
-
-		if (!list_empty(&n->slabs_full) ||
-		    !list_empty(&n->slabs_partial)) {
-			ret = -EBUSY;
-			break;
-		}
-	}
-	return ret;
-}
-
-static int __meminit slab_memory_callback(struct notifier_block *self,
-					unsigned long action, void *arg)
-{
-	struct memory_notify *mnb = arg;
-	int ret = 0;
-	int nid;
-
-	nid = mnb->status_change_nid;
-	if (nid < 0)
-		goto out;
-
-	switch (action) {
-	case MEM_GOING_ONLINE:
-		mutex_lock(&slab_mutex);
-		ret = init_cache_node_node(nid);
-		mutex_unlock(&slab_mutex);
-		break;
-	case MEM_GOING_OFFLINE:
-		mutex_lock(&slab_mutex);
-		ret = drain_cache_node_node(nid);
-		mutex_unlock(&slab_mutex);
-		break;
-	case MEM_ONLINE:
-	case MEM_OFFLINE:
-	case MEM_CANCEL_ONLINE:
-	case MEM_CANCEL_OFFLINE:
-		break;
-	}
-out:
-	return notifier_from_errno(ret);
-}
-#endif /* CONFIG_NUMA && CONFIG_MEMORY_HOTPLUG */
-
-/*
- * swap the static kmem_cache_node with kmalloced memory
- */
-static void __init init_list(struct kmem_cache *cachep, struct kmem_cache_node *list,
-				int nodeid)
-{
-	struct kmem_cache_node *ptr;
-
-	ptr = kmalloc_node(sizeof(struct kmem_cache_node), GFP_NOWAIT, nodeid);
-	BUG_ON(!ptr);
-
-	memcpy(ptr, list, sizeof(struct kmem_cache_node));
-	/*
-	 * Do not assume that spinlocks can be initialized via memcpy:
-	 */
-	spin_lock_init(&ptr->list_lock);
-
-	MAKE_ALL_LISTS(cachep, ptr, nodeid);
-	cachep->node[nodeid] = ptr;
-}
-
-/*
- * For setting up all the kmem_cache_node for cache whose buffer_size is same as
- * size of kmem_cache_node.
- */
-static void __init set_up_node(struct kmem_cache *cachep, int index)
-{
-	int node;
-
-	for_each_online_node(node) {
-		cachep->node[node] = &init_kmem_cache_node[index + node];
-		cachep->node[node]->next_reap = jiffies +
-		    REAPTIMEOUT_NODE +
-		    ((unsigned long)cachep) % REAPTIMEOUT_NODE;
-	}
-}
-
-/*
- * Initialisation.  Called after the page allocator have been initialised and
- * before smp_init().
- */
-void __init kmem_cache_init(void)
-{
-	int i;
-
-	kmem_cache = &kmem_cache_boot;
-
-	if (!IS_ENABLED(CONFIG_NUMA) || num_possible_nodes() == 1)
-		use_alien_caches = 0;
-
-	for (i = 0; i < NUM_INIT_LISTS; i++)
-		kmem_cache_node_init(&init_kmem_cache_node[i]);
-
-	/*
-	 * Fragmentation resistance on low memory - only use bigger
-	 * page orders on machines with more than 32MB of memory if
-	 * not overridden on the command line.
-	 */
-	if (!slab_max_order_set && totalram_pages() > (32 << 20) >> PAGE_SHIFT)
-		slab_max_order = SLAB_MAX_ORDER_HI;
-
-	/* Bootstrap is tricky, because several objects are allocated
-	 * from caches that do not exist yet:
-	 * 1) initialize the kmem_cache cache: it contains the struct
-	 *    kmem_cache structures of all caches, except kmem_cache itself:
-	 *    kmem_cache is statically allocated.
-	 *    Initially an __init data area is used for the head array and the
-	 *    kmem_cache_node structures, it's replaced with a kmalloc allocated
-	 *    array at the end of the bootstrap.
-	 * 2) Create the first kmalloc cache.
-	 *    The struct kmem_cache for the new cache is allocated normally.
-	 *    An __init data area is used for the head array.
-	 * 3) Create the remaining kmalloc caches, with minimally sized
-	 *    head arrays.
-	 * 4) Replace the __init data head arrays for kmem_cache and the first
-	 *    kmalloc cache with kmalloc allocated arrays.
-	 * 5) Replace the __init data for kmem_cache_node for kmem_cache and
-	 *    the other cache's with kmalloc allocated memory.
-	 * 6) Resize the head arrays of the kmalloc caches to their final sizes.
-	 */
-
-	/* 1) create the kmem_cache */
-
-	/*
-	 * struct kmem_cache size depends on nr_node_ids & nr_cpu_ids
-	 */
-	create_boot_cache(kmem_cache, "kmem_cache",
-		offsetof(struct kmem_cache, node) +
-				  nr_node_ids * sizeof(struct kmem_cache_node *),
-				  SLAB_HWCACHE_ALIGN, 0, 0);
-	list_add(&kmem_cache->list, &slab_caches);
-	memcg_link_cache(kmem_cache);
-	slab_state = PARTIAL;
-
-	/*
-	 * Initialize the caches that provide memory for the  kmem_cache_node
-	 * structures first.  Without this, further allocations will bug.
-	 */
-	kmalloc_caches[KMALLOC_NORMAL][INDEX_NODE] = create_kmalloc_cache(
-				kmalloc_info[INDEX_NODE].name,
-				kmalloc_size(INDEX_NODE), ARCH_KMALLOC_FLAGS,
-				0, kmalloc_size(INDEX_NODE));
-	slab_state = PARTIAL_NODE;
-	setup_kmalloc_cache_index_table();
-
-	slab_early_init = 0;
-
-	/* 5) Replace the bootstrap kmem_cache_node */
-	{
-		int nid;
-
-		for_each_online_node(nid) {
-			init_list(kmem_cache, &init_kmem_cache_node[CACHE_CACHE + nid], nid);
-
-			init_list(kmalloc_caches[KMALLOC_NORMAL][INDEX_NODE],
-					  &init_kmem_cache_node[SIZE_NODE + nid], nid);
-		}
-	}
-
-	create_kmalloc_caches(ARCH_KMALLOC_FLAGS);
-}
-
-void __init kmem_cache_init_late(void)
-{
-	struct kmem_cache *cachep;
-
-	/* 6) resize the head arrays to their final sizes */
-	mutex_lock(&slab_mutex);
-	list_for_each_entry(cachep, &slab_caches, list)
-		if (enable_cpucache(cachep, GFP_NOWAIT))
-			BUG();
-	mutex_unlock(&slab_mutex);
-
-	/* Done! */
-	slab_state = FULL;
-
-#ifdef CONFIG_NUMA
-	/*
-	 * Register a memory hotplug callback that initializes and frees
-	 * node.
-	 */
-	hotplug_memory_notifier(slab_memory_callback, SLAB_CALLBACK_PRI);
-#endif
-
-	/*
-	 * The reap timers are started later, with a module init call: That part
-	 * of the kernel is not yet operational.
-	 */
-}
-
-static int __init cpucache_init(void)
-{
-	int ret;
-
-	/*
-	 * Register the timers that return unneeded pages to the page allocator
-	 */
-	ret = cpuhp_setup_state(CPUHP_AP_ONLINE_DYN, "SLAB online",
-				slab_online_cpu, slab_offline_cpu);
-	WARN_ON(ret < 0);
-
-	return 0;
-}
-__initcall(cpucache_init);
-
-static noinline void
-slab_out_of_memory(struct kmem_cache *cachep, gfp_t gfpflags, int nodeid)
-{
-#if DEBUG
-	struct kmem_cache_node *n;
-	unsigned long flags;
-	int node;
-	static DEFINE_RATELIMIT_STATE(slab_oom_rs, DEFAULT_RATELIMIT_INTERVAL,
-				      DEFAULT_RATELIMIT_BURST);
-
-	if ((gfpflags & __GFP_NOWARN) || !__ratelimit(&slab_oom_rs))
-		return;
-
-	pr_warn("SLAB: Unable to allocate memory on node %d, gfp=%#x(%pGg)\n",
-		nodeid, gfpflags, &gfpflags);
-	pr_warn("  cache: %s, object size: %d, order: %d\n",
-		cachep->name, cachep->size, cachep->gfporder);
-
-	for_each_kmem_cache_node(cachep, node, n) {
-		unsigned long total_slabs, free_slabs, free_objs;
-
-		spin_lock_irqsave(&n->list_lock, flags);
-		total_slabs = n->total_slabs;
-		free_slabs = n->free_slabs;
-		free_objs = n->free_objects;
-		spin_unlock_irqrestore(&n->list_lock, flags);
-
-		pr_warn("  node %d: slabs: %ld/%ld, objs: %ld/%ld\n",
-			node, total_slabs - free_slabs, total_slabs,
-			(total_slabs * cachep->num) - free_objs,
-			total_slabs * cachep->num);
-	}
-#endif
-}
-
-/*
- * Interface to system's page allocator. No need to hold the
- * kmem_cache_node ->list_lock.
- *
- * If we requested dmaable memory, we will get it. Even if we
- * did not request dmaable memory, we might get it, but that
- * would be relatively rare and ignorable.
- */
-static struct page *kmem_getpages(struct kmem_cache *cachep, gfp_t flags,
-								int nodeid)
-{
-	struct page *page;
-	int nr_pages;
-
-	flags |= cachep->allocflags;
-
-	page = __alloc_pages_node(nodeid, flags, cachep->gfporder);
-	if (!page) {
-		slab_out_of_memory(cachep, flags, nodeid);
-		return NULL;
-	}
-
-	if (memcg_charge_slab(page, flags, cachep->gfporder, cachep)) {
-		__free_pages(page, cachep->gfporder);
-		return NULL;
-	}
-
-	nr_pages = (1 << cachep->gfporder);
-	if (cachep->flags & SLAB_RECLAIM_ACCOUNT)
-		mod_lruvec_page_state(page, NR_SLAB_RECLAIMABLE, nr_pages);
-	else
-		mod_lruvec_page_state(page, NR_SLAB_UNRECLAIMABLE, nr_pages);
-
-	__SetPageSlab(page);
-	/* Record if ALLOC_NO_WATERMARKS was set when allocating the slab */
-	if (sk_memalloc_socks() && page_is_pfmemalloc(page))
-		SetPageSlabPfmemalloc(page);
-
-	return page;
-}
-
-/*
- * Interface to system's page release.
- */
-static void kmem_freepages(struct kmem_cache *cachep, struct page *page)
-{
-	int order = cachep->gfporder;
-	unsigned long nr_freed = (1 << order);
-
-	if (cachep->flags & SLAB_RECLAIM_ACCOUNT)
-		mod_lruvec_page_state(page, NR_SLAB_RECLAIMABLE, -nr_freed);
-	else
-		mod_lruvec_page_state(page, NR_SLAB_UNRECLAIMABLE, -nr_freed);
-
-	BUG_ON(!PageSlab(page));
-	__ClearPageSlabPfmemalloc(page);
-	__ClearPageSlab(page);
-	page_mapcount_reset(page);
-	page->mapping = NULL;
-
-	if (current->reclaim_state)
-		current->reclaim_state->reclaimed_slab += nr_freed;
-	memcg_uncharge_slab(page, order, cachep);
-	__free_pages(page, order);
-}
-
-static void kmem_rcu_free(struct rcu_head *head)
-{
-	struct kmem_cache *cachep;
-	struct page *page;
-
-	page = container_of(head, struct page, rcu_head);
-	cachep = page->slab_cache;
-
-	kmem_freepages(cachep, page);
-}
-
-#if DEBUG
-static bool is_debug_pagealloc_cache(struct kmem_cache *cachep)
-{
-	if (debug_pagealloc_enabled() && OFF_SLAB(cachep) &&
-		(cachep->size % PAGE_SIZE) == 0)
-		return true;
-
-	return false;
-}
-
-#ifdef CONFIG_DEBUG_PAGEALLOC
-static void store_stackinfo(struct kmem_cache *cachep, unsigned long *addr,
-			    unsigned long caller)
-{
-	int size = cachep->object_size;
-
-	addr = (unsigned long *)&((char *)addr)[obj_offset(cachep)];
-
-	if (size < 5 * sizeof(unsigned long))
-		return;
-
-	*addr++ = 0x12345678;
-	*addr++ = caller;
-	*addr++ = smp_processor_id();
-	size -= 3 * sizeof(unsigned long);
-	{
-		unsigned long *sptr = &caller;
-		unsigned long svalue;
-
-		while (!kstack_end(sptr)) {
-			svalue = *sptr++;
-			if (kernel_text_address(svalue)) {
-				*addr++ = svalue;
-				size -= sizeof(unsigned long);
-				if (size <= sizeof(unsigned long))
-					break;
-			}
-		}
-
-	}
-	*addr++ = 0x87654321;
-}
-
-static void slab_kernel_map(struct kmem_cache *cachep, void *objp,
-				int map, unsigned long caller)
-{
-	if (!is_debug_pagealloc_cache(cachep))
-		return;
-
-	if (caller)
-		store_stackinfo(cachep, objp, caller);
-
-	kernel_map_pages(virt_to_page(objp), cachep->size / PAGE_SIZE, map);
-}
-
-#else
-static inline void slab_kernel_map(struct kmem_cache *cachep, void *objp,
-				int map, unsigned long caller) {}
-
-#endif
-
-static void poison_obj(struct kmem_cache *cachep, void *addr, unsigned char val)
-{
-	int size = cachep->object_size;
-	addr = &((char *)addr)[obj_offset(cachep)];
-
-	memset(addr, val, size);
-	*(unsigned char *)(addr + size - 1) = POISON_END;
-}
-
-static void dump_line(char *data, int offset, int limit)
-{
-	int i;
-	unsigned char error = 0;
-	int bad_count = 0;
-
-	pr_err("%03x: ", offset);
-	for (i = 0; i < limit; i++) {
-		if (data[offset + i] != POISON_FREE) {
-			error = data[offset + i];
-			bad_count++;
-		}
-	}
-	print_hex_dump(KERN_CONT, "", 0, 16, 1,
-			&data[offset], limit, 1);
-
-	if (bad_count == 1) {
-		error ^= POISON_FREE;
-		if (!(error & (error - 1))) {
-			pr_err("Single bit error detected. Probably bad RAM.\n");
-#ifdef CONFIG_X86
-			pr_err("Run memtest86+ or a similar memory test tool.\n");
-#else
-			pr_err("Run a memory test tool.\n");
-#endif
-		}
-	}
-}
-#endif
-
-#if DEBUG
-
-static void print_objinfo(struct kmem_cache *cachep, void *objp, int lines)
-{
-	int i, size;
-	char *realobj;
-
-	if (cachep->flags & SLAB_RED_ZONE) {
-		pr_err("Redzone: 0x%llx/0x%llx\n",
-		       *dbg_redzone1(cachep, objp),
-		       *dbg_redzone2(cachep, objp));
-	}
-
-	if (cachep->flags & SLAB_STORE_USER)
-		pr_err("Last user: (%pSR)\n", *dbg_userword(cachep, objp));
-	realobj = (char *)objp + obj_offset(cachep);
-	size = cachep->object_size;
-	for (i = 0; i < size && lines; i += 16, lines--) {
-		int limit;
-		limit = 16;
-		if (i + limit > size)
-			limit = size - i;
-		dump_line(realobj, i, limit);
-	}
-}
-
-static void check_poison_obj(struct kmem_cache *cachep, void *objp)
-{
-	char *realobj;
-	int size, i;
-	int lines = 0;
-
-	if (is_debug_pagealloc_cache(cachep))
-		return;
-
-	realobj = (char *)objp + obj_offset(cachep);
-	size = cachep->object_size;
-
-	for (i = 0; i < size; i++) {
-		char exp = POISON_FREE;
-		if (i == size - 1)
-			exp = POISON_END;
-		if (realobj[i] != exp) {
-			int limit;
-			/* Mismatch ! */
-			/* Print header */
-			if (lines == 0) {
-				pr_err("Slab corruption (%s): %s start=%px, len=%d\n",
-				       print_tainted(), cachep->name,
-				       realobj, size);
-				print_objinfo(cachep, objp, 0);
-			}
-			/* Hexdump the affected line */
-			i = (i / 16) * 16;
-			limit = 16;
-			if (i + limit > size)
-				limit = size - i;
-			dump_line(realobj, i, limit);
-			i += 16;
-			lines++;
-			/* Limit to 5 lines */
-			if (lines > 5)
-				break;
-		}
-	}
-	if (lines != 0) {
-		/* Print some data about the neighboring objects, if they
-		 * exist:
-		 */
-		struct page *page = virt_to_head_page(objp);
-		unsigned int objnr;
-
-		objnr = obj_to_index(cachep, page, objp);
-		if (objnr) {
-			objp = index_to_obj(cachep, page, objnr - 1);
-			realobj = (char *)objp + obj_offset(cachep);
-			pr_err("Prev obj: start=%px, len=%d\n", realobj, size);
-			print_objinfo(cachep, objp, 2);
-		}
-		if (objnr + 1 < cachep->num) {
-			objp = index_to_obj(cachep, page, objnr + 1);
-			realobj = (char *)objp + obj_offset(cachep);
-			pr_err("Next obj: start=%px, len=%d\n", realobj, size);
-			print_objinfo(cachep, objp, 2);
-		}
-	}
-}
-#endif
-
-#if DEBUG
-static void slab_destroy_debugcheck(struct kmem_cache *cachep,
-						struct page *page)
-{
-	int i;
-
-	if (OBJFREELIST_SLAB(cachep) && cachep->flags & SLAB_POISON) {
-		poison_obj(cachep, page->freelist - obj_offset(cachep),
-			POISON_FREE);
-	}
-
-	for (i = 0; i < cachep->num; i++) {
-		void *objp = index_to_obj(cachep, page, i);
-
-		if (cachep->flags & SLAB_POISON) {
-			check_poison_obj(cachep, objp);
-			slab_kernel_map(cachep, objp, 1, 0);
-		}
-		if (cachep->flags & SLAB_RED_ZONE) {
-			if (*dbg_redzone1(cachep, objp) != RED_INACTIVE)
-				slab_error(cachep, "start of a freed object was overwritten");
-			if (*dbg_redzone2(cachep, objp) != RED_INACTIVE)
-				slab_error(cachep, "end of a freed object was overwritten");
-		}
-	}
-}
-#else
-static void slab_destroy_debugcheck(struct kmem_cache *cachep,
-						struct page *page)
-{
-}
-#endif
-
-/**
- * slab_destroy - destroy and release all objects in a slab
- * @cachep: cache pointer being destroyed
- * @page: page pointer being destroyed
- *
- * Destroy all the objs in a slab page, and release the mem back to the system.
- * Before calling the slab page must have been unlinked from the cache. The
- * kmem_cache_node ->list_lock is not held/needed.
- */
-static void slab_destroy(struct kmem_cache *cachep, struct page *page)
-{
-	void *freelist;
-
-	freelist = page->freelist;
-	slab_destroy_debugcheck(cachep, page);
-	if (unlikely(cachep->flags & SLAB_TYPESAFE_BY_RCU))
-		call_rcu(&page->rcu_head, kmem_rcu_free);
-	else
-		kmem_freepages(cachep, page);
-
-	/*
-	 * From now on, we don't use freelist
-	 * although actual page can be freed in rcu context
-	 */
-	if (OFF_SLAB(cachep))
-		kmem_cache_free(cachep->freelist_cache, freelist);
-}
-
-static void slabs_destroy(struct kmem_cache *cachep, struct list_head *list)
-{
-	struct page *page, *n;
-
-	list_for_each_entry_safe(page, n, list, lru) {
-		list_del(&page->lru);
-		slab_destroy(cachep, page);
-	}
-}
-
-/**
- * calculate_slab_order - calculate size (page order) of slabs
- * @cachep: pointer to the cache that is being created
- * @size: size of objects to be created in this cache.
- * @flags: slab allocation flags
- *
- * Also calculates the number of objects per slab.
- *
- * This could be made much more intelligent.  For now, try to avoid using
- * high order pages for slabs.  When the gfp() functions are more friendly
- * towards high-order requests, this should be changed.
- *
- * Return: number of left-over bytes in a slab
- */
-static size_t calculate_slab_order(struct kmem_cache *cachep,
-				size_t size, slab_flags_t flags)
-{
-	size_t left_over = 0;
-	int gfporder;
-
-	for (gfporder = 0; gfporder <= KMALLOC_MAX_ORDER; gfporder++) {
-		unsigned int num;
-		size_t remainder;
-
-		num = cache_estimate(gfporder, size, flags, &remainder);
-		if (!num)
-			continue;
-
-		/* Can't handle number of objects more than SLAB_OBJ_MAX_NUM */
-		if (num > SLAB_OBJ_MAX_NUM)
-			break;
-
-		if (flags & CFLGS_OFF_SLAB) {
-			struct kmem_cache *freelist_cache;
-			size_t freelist_size;
-
-			freelist_size = num * sizeof(freelist_idx_t);
-			freelist_cache = kmalloc_slab(freelist_size, 0u);
-			if (!freelist_cache)
-				continue;
-
-			/*
-			 * Needed to avoid possible looping condition
-			 * in cache_grow_begin()
-			 */
-			if (OFF_SLAB(freelist_cache))
-				continue;
-
-			/* check if off slab has enough benefit */
-			if (freelist_cache->size > cachep->size / 2)
-				continue;
-		}
-
-		/* Found something acceptable - save it away */
-		cachep->num = num;
-		cachep->gfporder = gfporder;
-		left_over = remainder;
-
-		/*
-		 * A VFS-reclaimable slab tends to have most allocations
-		 * as GFP_NOFS and we really don't want to have to be allocating
-		 * higher-order pages when we are unable to shrink dcache.
-		 */
-		if (flags & SLAB_RECLAIM_ACCOUNT)
-			break;
-
-		/*
-		 * Large number of objects is good, but very large slabs are
-		 * currently bad for the gfp()s.
-		 */
-		if (gfporder >= slab_max_order)
-			break;
-
-		/*
-		 * Acceptable internal fragmentation?
-		 */
-		if (left_over * 8 <= (PAGE_SIZE << gfporder))
-			break;
-	}
-	return left_over;
-}
-
-static struct array_cache __percpu *alloc_kmem_cache_cpus(
-		struct kmem_cache *cachep, int entries, int batchcount)
-{
-	int cpu;
-	size_t size;
-	struct array_cache __percpu *cpu_cache;
-
-	size = sizeof(void *) * entries + sizeof(struct array_cache);
-	cpu_cache = __alloc_percpu(size, sizeof(void *));
-
-	if (!cpu_cache)
-		return NULL;
-
-	for_each_possible_cpu(cpu) {
-		init_arraycache(per_cpu_ptr(cpu_cache, cpu),
-				entries, batchcount);
-	}
-
-	return cpu_cache;
-}
-
-static int __ref setup_cpu_cache(struct kmem_cache *cachep, gfp_t gfp)
-{
-	if (slab_state >= FULL)
-		return enable_cpucache(cachep, gfp);
-
-	cachep->cpu_cache = alloc_kmem_cache_cpus(cachep, 1, 1);
-	if (!cachep->cpu_cache)
-		return 1;
-
-	if (slab_state == DOWN) {
-		/* Creation of first cache (kmem_cache). */
-		set_up_node(kmem_cache, CACHE_CACHE);
-	} else if (slab_state == PARTIAL) {
-		/* For kmem_cache_node */
-		set_up_node(cachep, SIZE_NODE);
-	} else {
-		int node;
-
-		for_each_online_node(node) {
-			cachep->node[node] = kmalloc_node(
-				sizeof(struct kmem_cache_node), gfp, node);
-			BUG_ON(!cachep->node[node]);
-			kmem_cache_node_init(cachep->node[node]);
-		}
-	}
-
-	cachep->node[numa_mem_id()]->next_reap =
-			jiffies + REAPTIMEOUT_NODE +
-			((unsigned long)cachep) % REAPTIMEOUT_NODE;
-
-	cpu_cache_get(cachep)->avail = 0;
-	cpu_cache_get(cachep)->limit = BOOT_CPUCACHE_ENTRIES;
-	cpu_cache_get(cachep)->batchcount = 1;
-	cpu_cache_get(cachep)->touched = 0;
-	cachep->batchcount = 1;
-	cachep->limit = BOOT_CPUCACHE_ENTRIES;
-	return 0;
-}
-
-slab_flags_t kmem_cache_flags(unsigned int object_size,
-	slab_flags_t flags, const char *name,
-	void (*ctor)(void *))
-{
-	return flags;
-}
-
-struct kmem_cache *
-__kmem_cache_alias(const char *name, unsigned int size, unsigned int align,
-		   slab_flags_t flags, void (*ctor)(void *))
-{
-	struct kmem_cache *cachep;
-
-	cachep = find_mergeable(size, align, flags, name, ctor);
-	if (cachep) {
-		cachep->refcount++;
-
-		/*
-		 * Adjust the object sizes so that we clear
-		 * the complete object on kzalloc.
-		 */
-		cachep->object_size = max_t(int, cachep->object_size, size);
-	}
-	return cachep;
-}
-
-static bool set_objfreelist_slab_cache(struct kmem_cache *cachep,
-			size_t size, slab_flags_t flags)
-{
-	size_t left;
-
-	cachep->num = 0;
-
-	if (cachep->ctor || flags & SLAB_TYPESAFE_BY_RCU)
-		return false;
-
-	left = calculate_slab_order(cachep, size,
-			flags | CFLGS_OBJFREELIST_SLAB);
-	if (!cachep->num)
-		return false;
-
-	if (cachep->num * sizeof(freelist_idx_t) > cachep->object_size)
-		return false;
-
-	cachep->colour = left / cachep->colour_off;
-
-	return true;
-}
-
-static bool set_off_slab_cache(struct kmem_cache *cachep,
-			size_t size, slab_flags_t flags)
-{
-	size_t left;
-
-	cachep->num = 0;
-
-	/*
-	 * Always use on-slab management when SLAB_NOLEAKTRACE
-	 * to avoid recursive calls into kmemleak.
-	 */
-	if (flags & SLAB_NOLEAKTRACE)
-		return false;
-
-	/*
-	 * Size is large, assume best to place the slab management obj
-	 * off-slab (should allow better packing of objs).
-	 */
-	left = calculate_slab_order(cachep, size, flags | CFLGS_OFF_SLAB);
-	if (!cachep->num)
-		return false;
-
-	/*
-	 * If the slab has been placed off-slab, and we have enough space then
-	 * move it on-slab. This is at the expense of any extra colouring.
-	 */
-	if (left >= cachep->num * sizeof(freelist_idx_t))
-		return false;
-
-	cachep->colour = left / cachep->colour_off;
-
-	return true;
-}
-
-static bool set_on_slab_cache(struct kmem_cache *cachep,
-			size_t size, slab_flags_t flags)
-{
-	size_t left;
-
-	cachep->num = 0;
-
-	left = calculate_slab_order(cachep, size, flags);
-	if (!cachep->num)
-		return false;
-
-	cachep->colour = left / cachep->colour_off;
-
-	return true;
-}
-
-/**
- * __kmem_cache_create - Create a cache.
- * @cachep: cache management descriptor
- * @flags: SLAB flags
- *
- * Returns a ptr to the cache on success, NULL on failure.
- * Cannot be called within a int, but can be interrupted.
- * The @ctor is run when new pages are allocated by the cache.
- *
- * The flags are
- *
- * %SLAB_POISON - Poison the slab with a known test pattern (a5a5a5a5)
- * to catch references to uninitialised memory.
- *
- * %SLAB_RED_ZONE - Insert `Red' zones around the allocated memory to check
- * for buffer overruns.
- *
- * %SLAB_HWCACHE_ALIGN - Align the objects in this cache to a hardware
- * cacheline.  This can be beneficial if you're counting cycles as closely
- * as davem.
- *
- * Return: a pointer to the created cache or %NULL in case of error
- */
-int __kmem_cache_create(struct kmem_cache *cachep, slab_flags_t flags)
-{
-	size_t ralign = BYTES_PER_WORD;
-	gfp_t gfp;
-	int err;
-	unsigned int size = cachep->size;
-
-#if DEBUG
-#if FORCED_DEBUG
-	/*
-	 * Enable redzoning and last user accounting, except for caches with
-	 * large objects, if the increased size would increase the object size
-	 * above the next power of two: caches with object sizes just above a
-	 * power of two have a significant amount of internal fragmentation.
-	 */
-	if (size < 4096 || fls(size - 1) == fls(size-1 + REDZONE_ALIGN +
-						2 * sizeof(unsigned long long)))
-		flags |= SLAB_RED_ZONE | SLAB_STORE_USER;
-	if (!(flags & SLAB_TYPESAFE_BY_RCU))
-		flags |= SLAB_POISON;
-#endif
-#endif
-
-	/*
-	 * Check that size is in terms of words.  This is needed to avoid
-	 * unaligned accesses for some archs when redzoning is used, and makes
-	 * sure any on-slab bufctl's are also correctly aligned.
-	 */
-	size = ALIGN(size, BYTES_PER_WORD);
-
-	if (flags & SLAB_RED_ZONE) {
-		ralign = REDZONE_ALIGN;
-		/* If redzoning, ensure that the second redzone is suitably
-		 * aligned, by adjusting the object size accordingly. */
-		size = ALIGN(size, REDZONE_ALIGN);
-	}
-
-	/* 3) caller mandated alignment */
-	if (ralign < cachep->align) {
-		ralign = cachep->align;
-	}
-	/* disable debug if necessary */
-	if (ralign > __alignof__(unsigned long long))
-		flags &= ~(SLAB_RED_ZONE | SLAB_STORE_USER);
-	/*
-	 * 4) Store it.
-	 */
-	cachep->align = ralign;
-	cachep->colour_off = cache_line_size();
-	/* Offset must be a multiple of the alignment. */
-	if (cachep->colour_off < cachep->align)
-		cachep->colour_off = cachep->align;
-
-	if (slab_is_available())
-		gfp = GFP_KERNEL;
-	else
-		gfp = GFP_NOWAIT;
-
-#if DEBUG
-
-	/*
-	 * Both debugging options require word-alignment which is calculated
-	 * into align above.
-	 */
-	if (flags & SLAB_RED_ZONE) {
-		/* add space for red zone words */
-		cachep->obj_offset += sizeof(unsigned long long);
-		size += 2 * sizeof(unsigned long long);
-	}
-	if (flags & SLAB_STORE_USER) {
-		/* user store requires one word storage behind the end of
-		 * the real object. But if the second red zone needs to be
-		 * aligned to 64 bits, we must allow that much space.
-		 */
-		if (flags & SLAB_RED_ZONE)
-			size += REDZONE_ALIGN;
-		else
-			size += BYTES_PER_WORD;
-	}
-#endif
-
-	kasan_cache_create(cachep, &size, &flags);
-
-	size = ALIGN(size, cachep->align);
-	/*
-	 * We should restrict the number of objects in a slab to implement
-	 * byte sized index. Refer comment on SLAB_OBJ_MIN_SIZE definition.
-	 */
-	if (FREELIST_BYTE_INDEX && size < SLAB_OBJ_MIN_SIZE)
-		size = ALIGN(SLAB_OBJ_MIN_SIZE, cachep->align);
-
-#if DEBUG
-	/*
-	 * To activate debug pagealloc, off-slab management is necessary
-	 * requirement. In early phase of initialization, small sized slab
-	 * doesn't get initialized so it would not be possible. So, we need
-	 * to check size >= 256. It guarantees that all necessary small
-	 * sized slab is initialized in current slab initialization sequence.
-	 */
-	if (debug_pagealloc_enabled() && (flags & SLAB_POISON) &&
-		size >= 256 && cachep->object_size > cache_line_size()) {
-		if (size < PAGE_SIZE || size % PAGE_SIZE == 0) {
-			size_t tmp_size = ALIGN(size, PAGE_SIZE);
-
-			if (set_off_slab_cache(cachep, tmp_size, flags)) {
-				flags |= CFLGS_OFF_SLAB;
-				cachep->obj_offset += tmp_size - size;
-				size = tmp_size;
-				goto done;
-			}
-		}
-	}
-#endif
-
-	if (set_objfreelist_slab_cache(cachep, size, flags)) {
-		flags |= CFLGS_OBJFREELIST_SLAB;
-		goto done;
-	}
-
-	if (set_off_slab_cache(cachep, size, flags)) {
-		flags |= CFLGS_OFF_SLAB;
-		goto done;
-	}
-
-	if (set_on_slab_cache(cachep, size, flags))
-		goto done;
-
-	return -E2BIG;
-
-done:
-	cachep->freelist_size = cachep->num * sizeof(freelist_idx_t);
-	cachep->flags = flags;
-	cachep->allocflags = __GFP_COMP;
-	if (flags & SLAB_CACHE_DMA)
-		cachep->allocflags |= GFP_DMA;
-	if (flags & SLAB_CACHE_DMA32)
-		cachep->allocflags |= GFP_DMA32;
-	if (flags & SLAB_RECLAIM_ACCOUNT)
-		cachep->allocflags |= __GFP_RECLAIMABLE;
-	cachep->size = size;
-	cachep->reciprocal_buffer_size = reciprocal_value(size);
-
-#if DEBUG
-	/*
-	 * If we're going to use the generic kernel_map_pages()
-	 * poisoning, then it's going to smash the contents of
-	 * the redzone and userword anyhow, so switch them off.
-	 */
-	if (IS_ENABLED(CONFIG_PAGE_POISONING) &&
-		(cachep->flags & SLAB_POISON) &&
-		is_debug_pagealloc_cache(cachep))
-		cachep->flags &= ~(SLAB_RED_ZONE | SLAB_STORE_USER);
-#endif
-
-	if (OFF_SLAB(cachep)) {
-		cachep->freelist_cache =
-			kmalloc_slab(cachep->freelist_size, 0u);
-	}
-
-	err = setup_cpu_cache(cachep, gfp);
-	if (err) {
-		__kmem_cache_release(cachep);
-		return err;
-	}
-
-	return 0;
-}
-
-#if DEBUG
-static void check_irq_off(void)
-{
-	BUG_ON(!irqs_disabled());
-}
-
-static void check_irq_on(void)
-{
-	BUG_ON(irqs_disabled());
-}
-
-static void check_mutex_acquired(void)
-{
-	BUG_ON(!mutex_is_locked(&slab_mutex));
-}
-
-static void check_spinlock_acquired(struct kmem_cache *cachep)
-{
-#ifdef CONFIG_SMP
-	check_irq_off();
-	assert_spin_locked(&get_node(cachep, numa_mem_id())->list_lock);
-#endif
-}
-
-static void check_spinlock_acquired_node(struct kmem_cache *cachep, int node)
-{
-#ifdef CONFIG_SMP
-	check_irq_off();
-	assert_spin_locked(&get_node(cachep, node)->list_lock);
-#endif
-}
-
-#else
-#define check_irq_off()	do { } while(0)
-#define check_irq_on()	do { } while(0)
-#define check_mutex_acquired()	do { } while(0)
-#define check_spinlock_acquired(x) do { } while(0)
-#define check_spinlock_acquired_node(x, y) do { } while(0)
-#endif
-
-static void drain_array_locked(struct kmem_cache *cachep, struct array_cache *ac,
-				int node, bool free_all, struct list_head *list)
-{
-	int tofree;
-
-	if (!ac || !ac->avail)
-		return;
-
-	tofree = free_all ? ac->avail : (ac->limit + 4) / 5;
-	if (tofree > ac->avail)
-		tofree = (ac->avail + 1) / 2;
-
-	free_block(cachep, ac->entry, tofree, node, list);
-	ac->avail -= tofree;
-	memmove(ac->entry, &(ac->entry[tofree]), sizeof(void *) * ac->avail);
-}
-
-static void do_drain(void *arg)
-{
-	struct kmem_cache *cachep = arg;
-	struct array_cache *ac;
-	int node = numa_mem_id();
-	struct kmem_cache_node *n;
-	LIST_HEAD(list);
-
-	check_irq_off();
-	ac = cpu_cache_get(cachep);
-	n = get_node(cachep, node);
-	spin_lock(&n->list_lock);
-	free_block(cachep, ac->entry, ac->avail, node, &list);
-	spin_unlock(&n->list_lock);
-	slabs_destroy(cachep, &list);
-	ac->avail = 0;
-}
-
-static void drain_cpu_caches(struct kmem_cache *cachep)
-{
-	struct kmem_cache_node *n;
-	int node;
-	LIST_HEAD(list);
-
-	on_each_cpu(do_drain, cachep, 1);
-	check_irq_on();
-	for_each_kmem_cache_node(cachep, node, n)
-		if (n->alien)
-			drain_alien_cache(cachep, n->alien);
-
-	for_each_kmem_cache_node(cachep, node, n) {
-		spin_lock_irq(&n->list_lock);
-		drain_array_locked(cachep, n->shared, node, true, &list);
-		spin_unlock_irq(&n->list_lock);
-
-		slabs_destroy(cachep, &list);
-	}
-}
-
-/*
- * Remove slabs from the list of free slabs.
- * Specify the number of slabs to drain in tofree.
- *
- * Returns the actual number of slabs released.
- */
-static int drain_freelist(struct kmem_cache *cache,
-			struct kmem_cache_node *n, int tofree)
-{
-	struct list_head *p;
-	int nr_freed;
-	struct page *page;
-
-	nr_freed = 0;
-	while (nr_freed < tofree && !list_empty(&n->slabs_free)) {
-
-		spin_lock_irq(&n->list_lock);
-		p = n->slabs_free.prev;
-		if (p == &n->slabs_free) {
-			spin_unlock_irq(&n->list_lock);
-			goto out;
-		}
-
-		page = list_entry(p, struct page, lru);
-		list_del(&page->lru);
-		n->free_slabs--;
-		n->total_slabs--;
-		/*
-		 * Safe to drop the lock. The slab is no longer linked
-		 * to the cache.
-		 */
-		n->free_objects -= cache->num;
-		spin_unlock_irq(&n->list_lock);
-		slab_destroy(cache, page);
-		nr_freed++;
-	}
-out:
-	return nr_freed;
-}
-
-bool __kmem_cache_empty(struct kmem_cache *s)
-{
-	int node;
-	struct kmem_cache_node *n;
-
-	for_each_kmem_cache_node(s, node, n)
-		if (!list_empty(&n->slabs_full) ||
-		    !list_empty(&n->slabs_partial))
-			return false;
-	return true;
-}
-
-int __kmem_cache_shrink(struct kmem_cache *cachep)
-{
-	int ret = 0;
-	int node;
-	struct kmem_cache_node *n;
-
-	drain_cpu_caches(cachep);
-
-	check_irq_on();
-	for_each_kmem_cache_node(cachep, node, n) {
-		drain_freelist(cachep, n, INT_MAX);
-
-		ret += !list_empty(&n->slabs_full) ||
-			!list_empty(&n->slabs_partial);
-	}
-	return (ret ? 1 : 0);
-}
-
-#ifdef CONFIG_MEMCG
-void __kmemcg_cache_deactivate(struct kmem_cache *cachep)
-{
-	__kmem_cache_shrink(cachep);
-}
-#endif
-
-int __kmem_cache_shutdown(struct kmem_cache *cachep)
-{
-	return __kmem_cache_shrink(cachep);
-}
-
-void __kmem_cache_release(struct kmem_cache *cachep)
-{
-	int i;
-	struct kmem_cache_node *n;
-
-	cache_random_seq_destroy(cachep);
-
-	free_percpu(cachep->cpu_cache);
-
-	/* NUMA: free the node structures */
-	for_each_kmem_cache_node(cachep, i, n) {
-		kfree(n->shared);
-		free_alien_cache(n->alien);
-		kfree(n);
-		cachep->node[i] = NULL;
-	}
-}
-
-/*
- * Get the memory for a slab management obj.
- *
- * For a slab cache when the slab descriptor is off-slab, the
- * slab descriptor can't come from the same cache which is being created,
- * Because if it is the case, that means we defer the creation of
- * the kmalloc_{dma,}_cache of size sizeof(slab descriptor) to this point.
- * And we eventually call down to __kmem_cache_create(), which
- * in turn looks up in the kmalloc_{dma,}_caches for the disired-size one.
- * This is a "chicken-and-egg" problem.
- *
- * So the off-slab slab descriptor shall come from the kmalloc_{dma,}_caches,
- * which are all initialized during kmem_cache_init().
- */
-static void *alloc_slabmgmt(struct kmem_cache *cachep,
-				   struct page *page, int colour_off,
-				   gfp_t local_flags, int nodeid)
-{
-	void *freelist;
-	void *addr = page_address(page);
-
-	page->s_mem = addr + colour_off;
-	page->active = 0;
-
-	if (OBJFREELIST_SLAB(cachep))
-		freelist = NULL;
-	else if (OFF_SLAB(cachep)) {
-		/* Slab management obj is off-slab. */
-		freelist = kmem_cache_alloc_node(cachep->freelist_cache,
-					      local_flags, nodeid);
-		freelist = kasan_reset_tag(freelist);
-		if (!freelist)
-			return NULL;
-	} else {
-		/* We will use last bytes at the slab for freelist */
-		freelist = addr + (PAGE_SIZE << cachep->gfporder) -
-				cachep->freelist_size;
-	}
-
-	return freelist;
-}
-
-static inline freelist_idx_t get_free_obj(struct page *page, unsigned int idx)
-{
-	return ((freelist_idx_t *)page->freelist)[idx];
-}
-
-static inline void set_free_obj(struct page *page,
-					unsigned int idx, freelist_idx_t val)
-{
-	((freelist_idx_t *)(page->freelist))[idx] = val;
-}
-
-static void cache_init_objs_debug(struct kmem_cache *cachep, struct page *page)
-{
-#if DEBUG
-	int i;
-
-	for (i = 0; i < cachep->num; i++) {
-		void *objp = index_to_obj(cachep, page, i);
-
-		if (cachep->flags & SLAB_STORE_USER)
-			*dbg_userword(cachep, objp) = NULL;
-
-		if (cachep->flags & SLAB_RED_ZONE) {
-			*dbg_redzone1(cachep, objp) = RED_INACTIVE;
-			*dbg_redzone2(cachep, objp) = RED_INACTIVE;
-		}
-		/*
-		 * Constructors are not allowed to allocate memory from the same
-		 * cache which they are a constructor for.  Otherwise, deadlock.
-		 * They must also be threaded.
-		 */
-		if (cachep->ctor && !(cachep->flags & SLAB_POISON)) {
-			kasan_unpoison_object_data(cachep,
-						   objp + obj_offset(cachep));
-			cachep->ctor(objp + obj_offset(cachep));
-			kasan_poison_object_data(
-				cachep, objp + obj_offset(cachep));
-		}
-
-		if (cachep->flags & SLAB_RED_ZONE) {
-			if (*dbg_redzone2(cachep, objp) != RED_INACTIVE)
-				slab_error(cachep, "constructor overwrote the end of an object");
-			if (*dbg_redzone1(cachep, objp) != RED_INACTIVE)
-				slab_error(cachep, "constructor overwrote the start of an object");
-		}
-		/* need to poison the objs? */
-		if (cachep->flags & SLAB_POISON) {
-			poison_obj(cachep, objp, POISON_FREE);
-			slab_kernel_map(cachep, objp, 0, 0);
-		}
-	}
-#endif
-}
-
-#ifdef CONFIG_SLAB_FREELIST_RANDOM
-/* Hold information during a freelist initialization */
-union freelist_init_state {
-	struct {
-		unsigned int pos;
-		unsigned int *list;
-		unsigned int count;
-	};
-	struct rnd_state rnd_state;
-};
-
-/*
- * Initialize the state based on the randomization methode available.
- * return true if the pre-computed list is available, false otherwize.
- */
-static bool freelist_state_initialize(union freelist_init_state *state,
-				struct kmem_cache *cachep,
-				unsigned int count)
-{
-	bool ret;
-	unsigned int rand;
-
-	/* Use best entropy available to define a random shift */
-	rand = get_random_int();
-
-	/* Use a random state if the pre-computed list is not available */
-	if (!cachep->random_seq) {
-		prandom_seed_state(&state->rnd_state, rand);
-		ret = false;
-	} else {
-		state->list = cachep->random_seq;
-		state->count = count;
-		state->pos = rand % count;
-		ret = true;
-	}
-	return ret;
-}
-
-/* Get the next entry on the list and randomize it using a random shift */
-static freelist_idx_t next_random_slot(union freelist_init_state *state)
-{
-	if (state->pos >= state->count)
-		state->pos = 0;
-	return state->list[state->pos++];
-}
-
-/* Swap two freelist entries */
-static void swap_free_obj(struct page *page, unsigned int a, unsigned int b)
-{
-	swap(((freelist_idx_t *)page->freelist)[a],
-		((freelist_idx_t *)page->freelist)[b]);
-}
-
-/*
- * Shuffle the freelist initialization state based on pre-computed lists.
- * return true if the list was successfully shuffled, false otherwise.
- */
-static bool shuffle_freelist(struct kmem_cache *cachep, struct page *page)
-{
-	unsigned int objfreelist = 0, i, rand, count = cachep->num;
-	union freelist_init_state state;
-	bool precomputed;
-
-	if (count < 2)
-		return false;
-
-	precomputed = freelist_state_initialize(&state, cachep, count);
-
-	/* Take a random entry as the objfreelist */
-	if (OBJFREELIST_SLAB(cachep)) {
-		if (!precomputed)
-			objfreelist = count - 1;
-		else
-			objfreelist = next_random_slot(&state);
-		page->freelist = index_to_obj(cachep, page, objfreelist) +
-						obj_offset(cachep);
-		count--;
-	}
-
-	/*
-	 * On early boot, generate the list dynamically.
-	 * Later use a pre-computed list for speed.
-	 */
-	if (!precomputed) {
-		for (i = 0; i < count; i++)
-			set_free_obj(page, i, i);
-
-		/* Fisher-Yates shuffle */
-		for (i = count - 1; i > 0; i--) {
-			rand = prandom_u32_state(&state.rnd_state);
-			rand %= (i + 1);
-			swap_free_obj(page, i, rand);
-		}
-	} else {
-		for (i = 0; i < count; i++)
-			set_free_obj(page, i, next_random_slot(&state));
-	}
-
-	if (OBJFREELIST_SLAB(cachep))
-		set_free_obj(page, cachep->num - 1, objfreelist);
-
-	return true;
-}
-#else
-static inline bool shuffle_freelist(struct kmem_cache *cachep,
-				struct page *page)
-{
-	return false;
-}
-#endif /* CONFIG_SLAB_FREELIST_RANDOM */
-
-static void cache_init_objs(struct kmem_cache *cachep,
-			    struct page *page)
-{
-	int i;
-	void *objp;
-	bool shuffled;
-
-	cache_init_objs_debug(cachep, page);
-
-	/* Try to randomize the freelist if enabled */
-	shuffled = shuffle_freelist(cachep, page);
-
-	if (!shuffled && OBJFREELIST_SLAB(cachep)) {
-		page->freelist = index_to_obj(cachep, page, cachep->num - 1) +
-						obj_offset(cachep);
-	}
-
-	for (i = 0; i < cachep->num; i++) {
-		objp = index_to_obj(cachep, page, i);
-		objp = kasan_init_slab_obj(cachep, objp);
-
-		/* constructor could break poison info */
-		if (DEBUG == 0 && cachep->ctor) {
-			kasan_unpoison_object_data(cachep, objp);
-			cachep->ctor(objp);
-			kasan_poison_object_data(cachep, objp);
-		}
-
-		if (!shuffled)
-			set_free_obj(page, i, i);
-	}
-}
-
-static void *slab_get_obj(struct kmem_cache *cachep, struct page *page)
-{
-	void *objp;
-
-	objp = index_to_obj(cachep, page, get_free_obj(page, page->active));
-	page->active++;
-
-#if DEBUG
-	if (cachep->flags & SLAB_STORE_USER)
-		set_store_user_dirty(cachep);
-#endif
-
-	return objp;
-}
-
-static void slab_put_obj(struct kmem_cache *cachep,
-			struct page *page, void *objp)
-{
-	unsigned int objnr = obj_to_index(cachep, page, objp);
-#if DEBUG
-	unsigned int i;
-
-	/* Verify double free bug */
-	for (i = page->active; i < cachep->num; i++) {
-		if (get_free_obj(page, i) == objnr) {
-			pr_err("slab: double free detected in cache '%s', objp %px\n",
-			       cachep->name, objp);
-			BUG();
-		}
-	}
-#endif
-	page->active--;
-	if (!page->freelist)
-		page->freelist = objp + obj_offset(cachep);
-
-	set_free_obj(page, page->active, objnr);
-}
-
-/*
- * Map pages beginning at addr to the given cache and slab. This is required
- * for the slab allocator to be able to lookup the cache and slab of a
- * virtual address for kfree, ksize, and slab debugging.
- */
-static void slab_map_pages(struct kmem_cache *cache, struct page *page,
-			   void *freelist)
-{
-	page->slab_cache = cache;
-	page->freelist = freelist;
-}
-
-/*
- * Grow (by 1) the number of slabs within a cache.  This is called by
- * kmem_cache_alloc() when there are no active objs left in a cache.
- */
-static struct page *cache_grow_begin(struct kmem_cache *cachep,
-				gfp_t flags, int nodeid)
-{
-	void *freelist;
-	size_t offset;
-	gfp_t local_flags;
-	int page_node;
-	struct kmem_cache_node *n;
-	struct page *page;
-
-	/*
-	 * Be lazy and only check for valid flags here,  keeping it out of the
-	 * critical path in kmem_cache_alloc().
-	 */
-	if (unlikely(flags & GFP_SLAB_BUG_MASK)) {
-		gfp_t invalid_mask = flags & GFP_SLAB_BUG_MASK;
-		flags &= ~GFP_SLAB_BUG_MASK;
-		pr_warn("Unexpected gfp: %#x (%pGg). Fixing up to gfp: %#x (%pGg). Fix your code!\n",
-				invalid_mask, &invalid_mask, flags, &flags);
-		dump_stack();
-	}
-	WARN_ON_ONCE(cachep->ctor && (flags & __GFP_ZERO));
-	local_flags = flags & (GFP_CONSTRAINT_MASK|GFP_RECLAIM_MASK);
-
-	check_irq_off();
-	if (gfpflags_allow_blocking(local_flags))
-		local_irq_enable();
-
-	/*
-	 * Get mem for the objs.  Attempt to allocate a physical page from
-	 * 'nodeid'.
-	 */
-	page = kmem_getpages(cachep, local_flags, nodeid);
-	if (!page)
-		goto failed;
-
-	page_node = page_to_nid(page);
-	n = get_node(cachep, page_node);
-
-	/* Get colour for the slab, and cal the next value. */
-	n->colour_next++;
-	if (n->colour_next >= cachep->colour)
-		n->colour_next = 0;
-
-	offset = n->colour_next;
-	if (offset >= cachep->colour)
-		offset = 0;
-
-	offset *= cachep->colour_off;
-
-	/*
-	 * Call kasan_poison_slab() before calling alloc_slabmgmt(), so
-	 * page_address() in the latter returns a non-tagged pointer,
-	 * as it should be for slab pages.
-	 */
-	kasan_poison_slab(page);
-
-	/* Get slab management. */
-	freelist = alloc_slabmgmt(cachep, page, offset,
-			local_flags & ~GFP_CONSTRAINT_MASK, page_node);
-	if (OFF_SLAB(cachep) && !freelist)
-		goto opps1;
-
-	slab_map_pages(cachep, page, freelist);
-
-	cache_init_objs(cachep, page);
-
-	if (gfpflags_allow_blocking(local_flags))
-		local_irq_disable();
-
-	return page;
-
-opps1:
-	kmem_freepages(cachep, page);
-failed:
-	if (gfpflags_allow_blocking(local_flags))
-		local_irq_disable();
-	return NULL;
-}
-
-static void cache_grow_end(struct kmem_cache *cachep, struct page *page)
-{
-	struct kmem_cache_node *n;
-	void *list = NULL;
-
-	check_irq_off();
-
-	if (!page)
-		return;
-
-	INIT_LIST_HEAD(&page->lru);
-	n = get_node(cachep, page_to_nid(page));
-
-	spin_lock(&n->list_lock);
-	n->total_slabs++;
-	if (!page->active) {
-		list_add_tail(&page->lru, &(n->slabs_free));
-		n->free_slabs++;
-	} else
-		fixup_slab_list(cachep, n, page, &list);
-
-	STATS_INC_GROWN(cachep);
-	n->free_objects += cachep->num - page->active;
-	spin_unlock(&n->list_lock);
-
-	fixup_objfreelist_debug(cachep, &list);
-}
-
-#if DEBUG
-
-/*
- * Perform extra freeing checks:
- * - detect bad pointers.
- * - POISON/RED_ZONE checking
- */
-static void kfree_debugcheck(const void *objp)
-{
-	if (!virt_addr_valid(objp)) {
-		pr_err("kfree_debugcheck: out of range ptr %lxh\n",
-		       (unsigned long)objp);
-		BUG();
-	}
-}
-
-static inline void verify_redzone_free(struct kmem_cache *cache, void *obj)
-{
-	unsigned long long redzone1, redzone2;
-
-	redzone1 = *dbg_redzone1(cache, obj);
-	redzone2 = *dbg_redzone2(cache, obj);
-
-	/*
-	 * Redzone is ok.
-	 */
-	if (redzone1 == RED_ACTIVE && redzone2 == RED_ACTIVE)
-		return;
-
-	if (redzone1 == RED_INACTIVE && redzone2 == RED_INACTIVE)
-		slab_error(cache, "double free detected");
-	else
-		slab_error(cache, "memory outside object was overwritten");
-
-	pr_err("%px: redzone 1:0x%llx, redzone 2:0x%llx\n",
-	       obj, redzone1, redzone2);
-}
-
-static void *cache_free_debugcheck(struct kmem_cache *cachep, void *objp,
-				   unsigned long caller)
-{
-	unsigned int objnr;
-	struct page *page;
-
-	BUG_ON(virt_to_cache(objp) != cachep);
-
-	objp -= obj_offset(cachep);
-	kfree_debugcheck(objp);
-	page = virt_to_head_page(objp);
-
-	if (cachep->flags & SLAB_RED_ZONE) {
-		verify_redzone_free(cachep, objp);
-		*dbg_redzone1(cachep, objp) = RED_INACTIVE;
-		*dbg_redzone2(cachep, objp) = RED_INACTIVE;
-	}
-	if (cachep->flags & SLAB_STORE_USER) {
-		set_store_user_dirty(cachep);
-		*dbg_userword(cachep, objp) = (void *)caller;
-	}
-
-	objnr = obj_to_index(cachep, page, objp);
-
-	BUG_ON(objnr >= cachep->num);
-	BUG_ON(objp != index_to_obj(cachep, page, objnr));
-
-	if (cachep->flags & SLAB_POISON) {
-		poison_obj(cachep, objp, POISON_FREE);
-		slab_kernel_map(cachep, objp, 0, caller);
-	}
-	return objp;
-}
-
-#else
-#define kfree_debugcheck(x) do { } while(0)
-#define cache_free_debugcheck(x,objp,z) (objp)
-#endif
-
-static inline void fixup_objfreelist_debug(struct kmem_cache *cachep,
-						void **list)
-{
-#if DEBUG
-	void *next = *list;
-	void *objp;
-
-	while (next) {
-		objp = next - obj_offset(cachep);
-		next = *(void **)next;
-		poison_obj(cachep, objp, POISON_FREE);
-	}
-#endif
-}
-
-static inline void fixup_slab_list(struct kmem_cache *cachep,
-				struct kmem_cache_node *n, struct page *page,
-				void **list)
-{
-	/* move slabp to correct slabp list: */
-	list_del(&page->lru);
-	if (page->active == cachep->num) {
-		list_add(&page->lru, &n->slabs_full);
-		if (OBJFREELIST_SLAB(cachep)) {
-#if DEBUG
-			/* Poisoning will be done without holding the lock */
-			if (cachep->flags & SLAB_POISON) {
-				void **objp = page->freelist;
-
-				*objp = *list;
-				*list = objp;
-			}
-#endif
-			page->freelist = NULL;
-		}
-	} else
-		list_add(&page->lru, &n->slabs_partial);
-}
-
-/* Try to find non-pfmemalloc slab if needed */
-static noinline struct page *get_valid_first_slab(struct kmem_cache_node *n,
-					struct page *page, bool pfmemalloc)
-{
-	if (!page)
-		return NULL;
-
-	if (pfmemalloc)
-		return page;
-
-	if (!PageSlabPfmemalloc(page))
-		return page;
-
-	/* No need to keep pfmemalloc slab if we have enough free objects */
-	if (n->free_objects > n->free_limit) {
-		ClearPageSlabPfmemalloc(page);
-		return page;
-	}
-
-	/* Move pfmemalloc slab to the end of list to speed up next search */
-	list_del(&page->lru);
-	if (!page->active) {
-		list_add_tail(&page->lru, &n->slabs_free);
-		n->free_slabs++;
-	} else
-		list_add_tail(&page->lru, &n->slabs_partial);
-
-	list_for_each_entry(page, &n->slabs_partial, lru) {
-		if (!PageSlabPfmemalloc(page))
-			return page;
-	}
-
-	n->free_touched = 1;
-	list_for_each_entry(page, &n->slabs_free, lru) {
-		if (!PageSlabPfmemalloc(page)) {
-			n->free_slabs--;
-			return page;
-		}
-	}
-
-	return NULL;
-}
-
-static struct page *get_first_slab(struct kmem_cache_node *n, bool pfmemalloc)
-{
-	struct page *page;
-
-	assert_spin_locked(&n->list_lock);
-	page = list_first_entry_or_null(&n->slabs_partial, struct page, lru);
-	if (!page) {
-		n->free_touched = 1;
-		page = list_first_entry_or_null(&n->slabs_free, struct page,
-						lru);
-		if (page)
-			n->free_slabs--;
-	}
-
-	if (sk_memalloc_socks())
-		page = get_valid_first_slab(n, page, pfmemalloc);
-
-	return page;
-}
-
-static noinline void *cache_alloc_pfmemalloc(struct kmem_cache *cachep,
-				struct kmem_cache_node *n, gfp_t flags)
-{
-	struct page *page;
-	void *obj;
-	void *list = NULL;
-
-	if (!gfp_pfmemalloc_allowed(flags))
-		return NULL;
-
-	spin_lock(&n->list_lock);
-	page = get_first_slab(n, true);
-	if (!page) {
-		spin_unlock(&n->list_lock);
-		return NULL;
-	}
-
-	obj = slab_get_obj(cachep, page);
-	n->free_objects--;
-
-	fixup_slab_list(cachep, n, page, &list);
-
-	spin_unlock(&n->list_lock);
-	fixup_objfreelist_debug(cachep, &list);
-
-	return obj;
-}
-
-/*
- * Slab list should be fixed up by fixup_slab_list() for existing slab
- * or cache_grow_end() for new slab
- */
-static __always_inline int alloc_block(struct kmem_cache *cachep,
-		struct array_cache *ac, struct page *page, int batchcount)
-{
-	/*
-	 * There must be at least one object available for
-	 * allocation.
-	 */
-	BUG_ON(page->active >= cachep->num);
-
-	while (page->active < cachep->num && batchcount--) {
-		STATS_INC_ALLOCED(cachep);
-		STATS_INC_ACTIVE(cachep);
-		STATS_SET_HIGH(cachep);
-
-		ac->entry[ac->avail++] = slab_get_obj(cachep, page);
-	}
-
-	return batchcount;
-}
-
-static void *cache_alloc_refill(struct kmem_cache *cachep, gfp_t flags)
-{
-	int batchcount;
-	struct kmem_cache_node *n;
-	struct array_cache *ac, *shared;
-	int node;
-	void *list = NULL;
-	struct page *page;
-
-	check_irq_off();
-	node = numa_mem_id();
-
-	ac = cpu_cache_get(cachep);
-	batchcount = ac->batchcount;
-	if (!ac->touched && batchcount > BATCHREFILL_LIMIT) {
-		/*
-		 * If there was little recent activity on this cache, then
-		 * perform only a partial refill.  Otherwise we could generate
-		 * refill bouncing.
-		 */
-		batchcount = BATCHREFILL_LIMIT;
-	}
-	n = get_node(cachep, node);
-
-	BUG_ON(ac->avail > 0 || !n);
-	shared = READ_ONCE(n->shared);
-	if (!n->free_objects && (!shared || !shared->avail))
-		goto direct_grow;
-
-	spin_lock(&n->list_lock);
-	shared = READ_ONCE(n->shared);
-
-	/* See if we can refill from the shared array */
-	if (shared && transfer_objects(ac, shared, batchcount)) {
-		shared->touched = 1;
-		goto alloc_done;
-	}
-
-	while (batchcount > 0) {
-		/* Get slab alloc is to come from. */
-		page = get_first_slab(n, false);
-		if (!page)
-			goto must_grow;
-
-		check_spinlock_acquired(cachep);
-
-		batchcount = alloc_block(cachep, ac, page, batchcount);
-		fixup_slab_list(cachep, n, page, &list);
-	}
-
-must_grow:
-	n->free_objects -= ac->avail;
-alloc_done:
-	spin_unlock(&n->list_lock);
-	fixup_objfreelist_debug(cachep, &list);
-
-direct_grow:
-	if (unlikely(!ac->avail)) {
-		/* Check if we can use obj in pfmemalloc slab */
-		if (sk_memalloc_socks()) {
-			void *obj = cache_alloc_pfmemalloc(cachep, n, flags);
-
-			if (obj)
-				return obj;
-		}
-
-		page = cache_grow_begin(cachep, gfp_exact_node(flags), node);
-
-		/*
-		 * cache_grow_begin() can reenable interrupts,
-		 * then ac could change.
-		 */
-		ac = cpu_cache_get(cachep);
-		if (!ac->avail && page)
-			alloc_block(cachep, ac, page, batchcount);
-		cache_grow_end(cachep, page);
-
-		if (!ac->avail)
-			return NULL;
-	}
-	ac->touched = 1;
-
-	return ac->entry[--ac->avail];
-}
-
-static inline void cache_alloc_debugcheck_before(struct kmem_cache *cachep,
-						gfp_t flags)
-{
-	might_sleep_if(gfpflags_allow_blocking(flags));
-}
-
-#if DEBUG
-static void *cache_alloc_debugcheck_after(struct kmem_cache *cachep,
-				gfp_t flags, void *objp, unsigned long caller)
-{
-	WARN_ON_ONCE(cachep->ctor && (flags & __GFP_ZERO));
-	if (!objp)
-		return objp;
-	if (cachep->flags & SLAB_POISON) {
-		check_poison_obj(cachep, objp);
-		slab_kernel_map(cachep, objp, 1, 0);
-		poison_obj(cachep, objp, POISON_INUSE);
-	}
-	if (cachep->flags & SLAB_STORE_USER)
-		*dbg_userword(cachep, objp) = (void *)caller;
-
-	if (cachep->flags & SLAB_RED_ZONE) {
-		if (*dbg_redzone1(cachep, objp) != RED_INACTIVE ||
-				*dbg_redzone2(cachep, objp) != RED_INACTIVE) {
-			slab_error(cachep, "double free, or memory outside object was overwritten");
-			pr_err("%px: redzone 1:0x%llx, redzone 2:0x%llx\n",
-			       objp, *dbg_redzone1(cachep, objp),
-			       *dbg_redzone2(cachep, objp));
-		}
-		*dbg_redzone1(cachep, objp) = RED_ACTIVE;
-		*dbg_redzone2(cachep, objp) = RED_ACTIVE;
-	}
-
-	objp += obj_offset(cachep);
-	if (cachep->ctor && cachep->flags & SLAB_POISON)
-		cachep->ctor(objp);
-	if (ARCH_SLAB_MINALIGN &&
-	    ((unsigned long)objp & (ARCH_SLAB_MINALIGN-1))) {
-		pr_err("0x%px: not aligned to ARCH_SLAB_MINALIGN=%d\n",
-		       objp, (int)ARCH_SLAB_MINALIGN);
-	}
-	return objp;
-}
-#else
-#define cache_alloc_debugcheck_after(a,b,objp,d) (objp)
-#endif
-
-static inline void *____cache_alloc(struct kmem_cache *cachep, gfp_t flags)
-{
-	void *objp;
-	struct array_cache *ac;
-
-	check_irq_off();
-
-	ac = cpu_cache_get(cachep);
-	if (likely(ac->avail)) {
-		ac->touched = 1;
-		objp = ac->entry[--ac->avail];
-
-		STATS_INC_ALLOCHIT(cachep);
-		goto out;
-	}
-
-	STATS_INC_ALLOCMISS(cachep);
-	objp = cache_alloc_refill(cachep, flags);
-	/*
-	 * the 'ac' may be updated by cache_alloc_refill(),
-	 * and kmemleak_erase() requires its correct value.
-	 */
-	ac = cpu_cache_get(cachep);
-
-out:
-	/*
-	 * To avoid a false negative, if an object that is in one of the
-	 * per-CPU caches is leaked, we need to make sure kmemleak doesn't
-	 * treat the array pointers as a reference to the object.
-	 */
-	if (objp)
-		kmemleak_erase(&ac->entry[ac->avail]);
-	return objp;
-}
-
-#ifdef CONFIG_NUMA
-/*
- * Try allocating on another node if PFA_SPREAD_SLAB is a mempolicy is set.
- *
- * If we are in_interrupt, then process context, including cpusets and
- * mempolicy, may not apply and should not be used for allocation policy.
- */
-static void *alternate_node_alloc(struct kmem_cache *cachep, gfp_t flags)
-{
-	int nid_alloc, nid_here;
-
-	if (in_interrupt() || (flags & __GFP_THISNODE))
-		return NULL;
-	nid_alloc = nid_here = numa_mem_id();
-	if (cpuset_do_slab_mem_spread() && (cachep->flags & SLAB_MEM_SPREAD))
-		nid_alloc = cpuset_slab_spread_node();
-	else if (current->mempolicy)
-		nid_alloc = mempolicy_slab_node();
-	if (nid_alloc != nid_here)
-		return ____cache_alloc_node(cachep, flags, nid_alloc);
-	return NULL;
-}
-
-/*
- * Fallback function if there was no memory available and no objects on a
- * certain node and fall back is permitted. First we scan all the
- * available node for available objects. If that fails then we
- * perform an allocation without specifying a node. This allows the page
- * allocator to do its reclaim / fallback magic. We then insert the
- * slab into the proper nodelist and then allocate from it.
- */
-static void *fallback_alloc(struct kmem_cache *cache, gfp_t flags)
-{
-	struct zonelist *zonelist;
-	struct zoneref *z;
-	struct zone *zone;
-	enum zone_type high_zoneidx = gfp_zone(flags);
-	void *obj = NULL;
-	struct page *page;
-	int nid;
-	unsigned int cpuset_mems_cookie;
-
-	if (flags & __GFP_THISNODE)
-		return NULL;
-
-retry_cpuset:
-	cpuset_mems_cookie = read_mems_allowed_begin();
-	zonelist = node_zonelist(mempolicy_slab_node(), flags);
-
-retry:
-	/*
-	 * Look through allowed nodes for objects available
-	 * from existing per node queues.
-	 */
-	for_each_zone_zonelist(zone, z, zonelist, high_zoneidx) {
-		nid = zone_to_nid(zone);
-
-		if (cpuset_zone_allowed(zone, flags) &&
-			get_node(cache, nid) &&
-			get_node(cache, nid)->free_objects) {
-				obj = ____cache_alloc_node(cache,
-					gfp_exact_node(flags), nid);
-				if (obj)
-					break;
-		}
-	}
-
-	if (!obj) {
-		/*
-		 * This allocation will be performed within the constraints
-		 * of the current cpuset / memory policy requirements.
-		 * We may trigger various forms of reclaim on the allowed
-		 * set and go into memory reserves if necessary.
-		 */
-		page = cache_grow_begin(cache, flags, numa_mem_id());
-		cache_grow_end(cache, page);
-		if (page) {
-			nid = page_to_nid(page);
-			obj = ____cache_alloc_node(cache,
-				gfp_exact_node(flags), nid);
-
-			/*
-			 * Another processor may allocate the objects in
-			 * the slab since we are not holding any locks.
-			 */
-			if (!obj)
-				goto retry;
-		}
-	}
-
-	if (unlikely(!obj && read_mems_allowed_retry(cpuset_mems_cookie)))
-		goto retry_cpuset;
-	return obj;
-}
-
-/*
- * A interface to enable slab creation on nodeid
- */
-static void *____cache_alloc_node(struct kmem_cache *cachep, gfp_t flags,
-				int nodeid)
-{
-	struct page *page;
-	struct kmem_cache_node *n;
-	void *obj = NULL;
-	void *list = NULL;
-
-	VM_BUG_ON(nodeid < 0 || nodeid >= MAX_NUMNODES);
-	n = get_node(cachep, nodeid);
-	BUG_ON(!n);
-
-	check_irq_off();
-	spin_lock(&n->list_lock);
-	page = get_first_slab(n, false);
-	if (!page)
-		goto must_grow;
-
-	check_spinlock_acquired_node(cachep, nodeid);
-
-	STATS_INC_NODEALLOCS(cachep);
-	STATS_INC_ACTIVE(cachep);
-	STATS_SET_HIGH(cachep);
-
-	BUG_ON(page->active == cachep->num);
-
-	obj = slab_get_obj(cachep, page);
-	n->free_objects--;
-
-	fixup_slab_list(cachep, n, page, &list);
-
-	spin_unlock(&n->list_lock);
-	fixup_objfreelist_debug(cachep, &list);
-	return obj;
-
-must_grow:
-	spin_unlock(&n->list_lock);
-	page = cache_grow_begin(cachep, gfp_exact_node(flags), nodeid);
-	if (page) {
-		/* This slab isn't counted yet so don't update free_objects */
-		obj = slab_get_obj(cachep, page);
-	}
-	cache_grow_end(cachep, page);
-
-	return obj ? obj : fallback_alloc(cachep, flags);
-}
-
-static __always_inline void *
-slab_alloc_node(struct kmem_cache *cachep, gfp_t flags, int nodeid,
-		   unsigned long caller)
-{
-	unsigned long save_flags;
-	void *ptr;
-	int slab_node = numa_mem_id();
-
-	flags &= gfp_allowed_mask;
-	cachep = slab_pre_alloc_hook(cachep, flags);
-	if (unlikely(!cachep))
-		return NULL;
-
-	cache_alloc_debugcheck_before(cachep, flags);
-	local_irq_save(save_flags);
-
-	if (nodeid == NUMA_NO_NODE)
-		nodeid = slab_node;
-
-	if (unlikely(!get_node(cachep, nodeid))) {
-		/* Node not bootstrapped yet */
-		ptr = fallback_alloc(cachep, flags);
-		goto out;
-	}
-
-	if (nodeid == slab_node) {
-		/*
-		 * Use the locally cached objects if possible.
-		 * However ____cache_alloc does not allow fallback
-		 * to other nodes. It may fail while we still have
-		 * objects on other nodes available.
-		 */
-		ptr = ____cache_alloc(cachep, flags);
-		if (ptr)
-			goto out;
-	}
-	/* ___cache_alloc_node can fall back to other nodes */
-	ptr = ____cache_alloc_node(cachep, flags, nodeid);
-  out:
-	local_irq_restore(save_flags);
-	ptr = cache_alloc_debugcheck_after(cachep, flags, ptr, caller);
-
-	if (unlikely(flags & __GFP_ZERO) && ptr)
-		memset(ptr, 0, cachep->object_size);
-
-	slab_post_alloc_hook(cachep, flags, 1, &ptr);
-	return ptr;
-}
-
-static __always_inline void *
-__do_cache_alloc(struct kmem_cache *cache, gfp_t flags)
-{
-	void *objp;
-
-	if (current->mempolicy || cpuset_do_slab_mem_spread()) {
-		objp = alternate_node_alloc(cache, flags);
-		if (objp)
-			goto out;
-	}
-	objp = ____cache_alloc(cache, flags);
-
-	/*
-	 * We may just have run out of memory on the local node.
-	 * ____cache_alloc_node() knows how to locate memory on other nodes
-	 */
-	if (!objp)
-		objp = ____cache_alloc_node(cache, flags, numa_mem_id());
-
-  out:
-	return objp;
-}
-#else
-
-static __always_inline void *
-__do_cache_alloc(struct kmem_cache *cachep, gfp_t flags)
-{
-	return ____cache_alloc(cachep, flags);
-}
-
-#endif /* CONFIG_NUMA */
-
-static __always_inline void *
-slab_alloc(struct kmem_cache *cachep, gfp_t flags, unsigned long caller)
-{
-	unsigned long save_flags;
-	void *objp;
-
-	flags &= gfp_allowed_mask;
-	cachep = slab_pre_alloc_hook(cachep, flags);
-	if (unlikely(!cachep))
-		return NULL;
-
-	cache_alloc_debugcheck_before(cachep, flags);
-	local_irq_save(save_flags);
-	objp = __do_cache_alloc(cachep, flags);
-	local_irq_restore(save_flags);
-	objp = cache_alloc_debugcheck_after(cachep, flags, objp, caller);
-	prefetchw(objp);
-
-	if (unlikely(flags & __GFP_ZERO) && objp)
-		memset(objp, 0, cachep->object_size);
-
-	slab_post_alloc_hook(cachep, flags, 1, &objp);
-	return objp;
-}
-
-/*
- * Caller needs to acquire correct kmem_cache_node's list_lock
- * @list: List of detached free slabs should be freed by caller
- */
-static void free_block(struct kmem_cache *cachep, void **objpp,
-			int nr_objects, int node, struct list_head *list)
-{
-	int i;
-	struct kmem_cache_node *n = get_node(cachep, node);
-	struct page *page;
-
-	n->free_objects += nr_objects;
-
-	for (i = 0; i < nr_objects; i++) {
-		void *objp;
-		struct page *page;
-
-		objp = objpp[i];
-
-		page = virt_to_head_page(objp);
-		list_del(&page->lru);
-		check_spinlock_acquired_node(cachep, node);
-		slab_put_obj(cachep, page, objp);
-		STATS_DEC_ACTIVE(cachep);
-
-		/* fixup slab chains */
-		if (page->active == 0) {
-			list_add(&page->lru, &n->slabs_free);
-			n->free_slabs++;
-		} else {
-			/* Unconditionally move a slab to the end of the
-			 * partial list on free - maximum time for the
-			 * other objects to be freed, too.
-			 */
-			list_add_tail(&page->lru, &n->slabs_partial);
-		}
-	}
-
-	while (n->free_objects > n->free_limit && !list_empty(&n->slabs_free)) {
-		n->free_objects -= cachep->num;
-
-		page = list_last_entry(&n->slabs_free, struct page, lru);
-		list_move(&page->lru, list);
-		n->free_slabs--;
-		n->total_slabs--;
-	}
-}
-
-static void cache_flusharray(struct kmem_cache *cachep, struct array_cache *ac)
-{
-	int batchcount;
-	struct kmem_cache_node *n;
-	int node = numa_mem_id();
-	LIST_HEAD(list);
-
-	batchcount = ac->batchcount;
-
-	check_irq_off();
-	n = get_node(cachep, node);
-	spin_lock(&n->list_lock);
-	if (n->shared) {
-		struct array_cache *shared_array = n->shared;
-		int max = shared_array->limit - shared_array->avail;
-		if (max) {
-			if (batchcount > max)
-				batchcount = max;
-			memcpy(&(shared_array->entry[shared_array->avail]),
-			       ac->entry, sizeof(void *) * batchcount);
-			shared_array->avail += batchcount;
-			goto free_done;
-		}
-	}
-
-	free_block(cachep, ac->entry, batchcount, node, &list);
-free_done:
-#if STATS
-	{
-		int i = 0;
-		struct page *page;
-
-		list_for_each_entry(page, &n->slabs_free, lru) {
-			BUG_ON(page->active);
-
-			i++;
-		}
-		STATS_SET_FREEABLE(cachep, i);
-	}
-#endif
-	spin_unlock(&n->list_lock);
-	slabs_destroy(cachep, &list);
-	ac->avail -= batchcount;
-	memmove(ac->entry, &(ac->entry[batchcount]), sizeof(void *)*ac->avail);
-}
-
-/*
- * Release an obj back to its cache. If the obj has a constructed state, it must
- * be in this state _before_ it is released.  Called with disabled ints.
- */
-static __always_inline void __cache_free(struct kmem_cache *cachep, void *objp,
-					 unsigned long caller)
-{
-	/* Put the object into the quarantine, don't touch it for now. */
-	if (kasan_slab_free(cachep, objp, _RET_IP_))
-		return;
-
-	___cache_free(cachep, objp, caller);
-}
-
-void ___cache_free(struct kmem_cache *cachep, void *objp,
-		unsigned long caller)
-{
-	struct array_cache *ac = cpu_cache_get(cachep);
-
-	check_irq_off();
-	kmemleak_free_recursive(objp, cachep->flags);
-	objp = cache_free_debugcheck(cachep, objp, caller);
-
-	/*
-	 * Skip calling cache_free_alien() when the platform is not numa.
-	 * This will avoid cache misses that happen while accessing slabp (which
-	 * is per page memory  reference) to get nodeid. Instead use a global
-	 * variable to skip the call, which is mostly likely to be present in
-	 * the cache.
-	 */
-	if (nr_online_nodes > 1 && cache_free_alien(cachep, objp))
-		return;
-
-	if (ac->avail < ac->limit) {
-		STATS_INC_FREEHIT(cachep);
-	} else {
-		STATS_INC_FREEMISS(cachep);
-		cache_flusharray(cachep, ac);
-	}
-
-	if (sk_memalloc_socks()) {
-		struct page *page = virt_to_head_page(objp);
-
-		if (unlikely(PageSlabPfmemalloc(page))) {
-			cache_free_pfmemalloc(cachep, page, objp);
-			return;
-		}
-	}
-
-	ac->entry[ac->avail++] = objp;
-}
-
-/**
- * kmem_cache_alloc - Allocate an object
- * @cachep: The cache to allocate from.
- * @flags: See kmalloc().
- *
- * Allocate an object from this cache.  The flags are only relevant
- * if the cache has no available objects.
- *
- * Return: pointer to the new object or %NULL in case of error
- */
-void *kmem_cache_alloc(struct kmem_cache *cachep, gfp_t flags)
-{
-	void *ret = slab_alloc(cachep, flags, _RET_IP_);
-
-	trace_kmem_cache_alloc(_RET_IP_, ret,
-			       cachep->object_size, cachep->size, flags);
-
-	return ret;
-}
-EXPORT_SYMBOL(kmem_cache_alloc);
-
-static __always_inline void
-cache_alloc_debugcheck_after_bulk(struct kmem_cache *s, gfp_t flags,
-				  size_t size, void **p, unsigned long caller)
-{
-	size_t i;
-
-	for (i = 0; i < size; i++)
-		p[i] = cache_alloc_debugcheck_after(s, flags, p[i], caller);
-}
-
-int kmem_cache_alloc_bulk(struct kmem_cache *s, gfp_t flags, size_t size,
-			  void **p)
-{
-	size_t i;
-
-	s = slab_pre_alloc_hook(s, flags);
-	if (!s)
-		return 0;
-
-	cache_alloc_debugcheck_before(s, flags);
-
-	local_irq_disable();
-	for (i = 0; i < size; i++) {
-		void *objp = __do_cache_alloc(s, flags);
-
-		if (unlikely(!objp))
-			goto error;
-		p[i] = objp;
-	}
-	local_irq_enable();
-
-	cache_alloc_debugcheck_after_bulk(s, flags, size, p, _RET_IP_);
-
-	/* Clear memory outside IRQ disabled section */
-	if (unlikely(flags & __GFP_ZERO))
-		for (i = 0; i < size; i++)
-			memset(p[i], 0, s->object_size);
-
-	slab_post_alloc_hook(s, flags, size, p);
-	/* FIXME: Trace call missing. Christoph would like a bulk variant */
-	return size;
-error:
-	local_irq_enable();
-	cache_alloc_debugcheck_after_bulk(s, flags, i, p, _RET_IP_);
-	slab_post_alloc_hook(s, flags, i, p);
-	__kmem_cache_free_bulk(s, i, p);
-	return 0;
-}
-EXPORT_SYMBOL(kmem_cache_alloc_bulk);
-
-#ifdef CONFIG_TRACING
-void *
-kmem_cache_alloc_trace(struct kmem_cache *cachep, gfp_t flags, size_t size)
-{
-	void *ret;
-
-	ret = slab_alloc(cachep, flags, _RET_IP_);
-
-	ret = kasan_kmalloc(cachep, ret, size, flags);
-	trace_kmalloc(_RET_IP_, ret,
-		      size, cachep->size, flags);
-	return ret;
-}
-EXPORT_SYMBOL(kmem_cache_alloc_trace);
-#endif
-
-#ifdef CONFIG_NUMA
-/**
- * kmem_cache_alloc_node - Allocate an object on the specified node
- * @cachep: The cache to allocate from.
- * @flags: See kmalloc().
- * @nodeid: node number of the target node.
- *
- * Identical to kmem_cache_alloc but it will allocate memory on the given
- * node, which can improve the performance for cpu bound structures.
- *
- * Fallback to other node is possible if __GFP_THISNODE is not set.
- *
- * Return: pointer to the new object or %NULL in case of error
- */
-void *kmem_cache_alloc_node(struct kmem_cache *cachep, gfp_t flags, int nodeid)
-{
-	void *ret = slab_alloc_node(cachep, flags, nodeid, _RET_IP_);
-
-	trace_kmem_cache_alloc_node(_RET_IP_, ret,
-				    cachep->object_size, cachep->size,
-				    flags, nodeid);
-
-	return ret;
-}
-EXPORT_SYMBOL(kmem_cache_alloc_node);
-
-#ifdef CONFIG_TRACING
-void *kmem_cache_alloc_node_trace(struct kmem_cache *cachep,
-				  gfp_t flags,
-				  int nodeid,
-				  size_t size)
-{
-	void *ret;
-
-	ret = slab_alloc_node(cachep, flags, nodeid, _RET_IP_);
-
-	ret = kasan_kmalloc(cachep, ret, size, flags);
-	trace_kmalloc_node(_RET_IP_, ret,
-			   size, cachep->size,
-			   flags, nodeid);
-	return ret;
-}
-EXPORT_SYMBOL(kmem_cache_alloc_node_trace);
-#endif
-
-static __always_inline void *
-__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;
-	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);
-
-	return ret;
-}
-
-void *__kmalloc_node(size_t size, gfp_t flags, int node)
-{
-	return __do_kmalloc_node(size, flags, node, _RET_IP_);
-}
-EXPORT_SYMBOL(__kmalloc_node);
-
-void *__kmalloc_node_track_caller(size_t size, gfp_t flags,
-		int node, unsigned long caller)
-{
-	return __do_kmalloc_node(size, flags, node, caller);
-}
-EXPORT_SYMBOL(__kmalloc_node_track_caller);
-#endif /* CONFIG_NUMA */
-
-/**
- * __do_kmalloc - allocate memory
- * @size: how many bytes of memory are required.
- * @flags: the type of memory to allocate (see kmalloc).
- * @caller: function caller for debug tracking of the caller
- *
- * Return: pointer to the allocated memory or %NULL in case of error
- */
-static __always_inline void *__do_kmalloc(size_t size, gfp_t flags,
-					  unsigned long caller)
-{
-	struct kmem_cache *cachep;
-	void *ret;
-
-	if (unlikely(size > KMALLOC_MAX_CACHE_SIZE))
-		return NULL;
-	cachep = kmalloc_slab(size, flags);
-	if (unlikely(ZERO_OR_NULL_PTR(cachep)))
-		return cachep;
-	ret = slab_alloc(cachep, flags, caller);
-
-	ret = kasan_kmalloc(cachep, ret, size, flags);
-	trace_kmalloc(caller, ret,
-		      size, cachep->size, flags);
-
-	return ret;
-}
-
-void *__kmalloc(size_t size, gfp_t flags)
-{
-	return __do_kmalloc(size, flags, _RET_IP_);
-}
-EXPORT_SYMBOL(__kmalloc);
-
-void *__kmalloc_track_caller(size_t size, gfp_t flags, unsigned long caller)
-{
-	return __do_kmalloc(size, flags, caller);
-}
-EXPORT_SYMBOL(__kmalloc_track_caller);
-
-/**
- * kmem_cache_free - Deallocate an object
- * @cachep: The cache the allocation was from.
- * @objp: The previously allocated object.
- *
- * Free an object which was previously allocated from this
- * cache.
- */
-void kmem_cache_free(struct kmem_cache *cachep, void *objp)
-{
-	unsigned long flags;
-	cachep = cache_from_obj(cachep, objp);
-	if (!cachep)
-		return;
-
-	local_irq_save(flags);
-	debug_check_no_locks_freed(objp, cachep->object_size);
-	if (!(cachep->flags & SLAB_DEBUG_OBJECTS))
-		debug_check_no_obj_freed(objp, cachep->object_size);
-	__cache_free(cachep, objp, _RET_IP_);
-	local_irq_restore(flags);
-
-	trace_kmem_cache_free(_RET_IP_, objp);
-}
-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++) {
-		void *objp = p[i];
-
-		if (!orig_s) /* called via kfree_bulk */
-			s = virt_to_cache(objp);
-		else
-			s = cache_from_obj(orig_s, objp);
-
-		debug_check_no_locks_freed(objp, s->object_size);
-		if (!(s->flags & SLAB_DEBUG_OBJECTS))
-			debug_check_no_obj_freed(objp, s->object_size);
-
-		__cache_free(s, objp, _RET_IP_);
-	}
-	local_irq_enable();
-
-	/* FIXME: add tracing */
-}
-EXPORT_SYMBOL(kmem_cache_free_bulk);
-
-/**
- * kfree - free previously allocated memory
- * @objp: pointer returned by kmalloc.
- *
- * If @objp is NULL, no operation is performed.
- *
- * Don't free memory not originally allocated by kmalloc()
- * or you will run into trouble.
- */
-void kfree(const void *objp)
-{
-	struct kmem_cache *c;
-	unsigned long flags;
-
-	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);
-	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);
-}
-EXPORT_SYMBOL(kfree);
-
-/*
- * This initializes kmem_cache_node or resizes various caches for all nodes.
- */
-static int setup_kmem_cache_nodes(struct kmem_cache *cachep, gfp_t gfp)
-{
-	int ret;
-	int node;
-	struct kmem_cache_node *n;
-
-	for_each_online_node(node) {
-		ret = setup_kmem_cache_node(cachep, node, gfp, true);
-		if (ret)
-			goto fail;
-
-	}
-
-	return 0;
-
-fail:
-	if (!cachep->list.next) {
-		/* Cache is not active yet. Roll back what we did */
-		node--;
-		while (node >= 0) {
-			n = get_node(cachep, node);
-			if (n) {
-				kfree(n->shared);
-				free_alien_cache(n->alien);
-				kfree(n);
-				cachep->node[node] = NULL;
-			}
-			node--;
-		}
-	}
-	return -ENOMEM;
-}
-
-/* Always called with the slab_mutex held */
-static int __do_tune_cpucache(struct kmem_cache *cachep, int limit,
-				int batchcount, int shared, gfp_t gfp)
-{
-	struct array_cache __percpu *cpu_cache, *prev;
-	int cpu;
-
-	cpu_cache = alloc_kmem_cache_cpus(cachep, limit, batchcount);
-	if (!cpu_cache)
-		return -ENOMEM;
-
-	prev = cachep->cpu_cache;
-	cachep->cpu_cache = cpu_cache;
-	/*
-	 * Without a previous cpu_cache there's no need to synchronize remote
-	 * cpus, so skip the IPIs.
-	 */
-	if (prev)
-		kick_all_cpus_sync();
-
-	check_irq_on();
-	cachep->batchcount = batchcount;
-	cachep->limit = limit;
-	cachep->shared = shared;
-
-	if (!prev)
-		goto setup_node;
-
-	for_each_online_cpu(cpu) {
-		LIST_HEAD(list);
-		int node;
-		struct kmem_cache_node *n;
-		struct array_cache *ac = per_cpu_ptr(prev, cpu);
-
-		node = cpu_to_mem(cpu);
-		n = get_node(cachep, node);
-		spin_lock_irq(&n->list_lock);
-		free_block(cachep, ac->entry, ac->avail, node, &list);
-		spin_unlock_irq(&n->list_lock);
-		slabs_destroy(cachep, &list);
-	}
-	free_percpu(prev);
-
-setup_node:
-	return setup_kmem_cache_nodes(cachep, gfp);
-}
-
-static int do_tune_cpucache(struct kmem_cache *cachep, int limit,
-				int batchcount, int shared, gfp_t gfp)
-{
-	int ret;
-	struct kmem_cache *c;
-
-	ret = __do_tune_cpucache(cachep, limit, batchcount, shared, gfp);
-
-	if (slab_state < FULL)
-		return ret;
-
-	if ((ret < 0) || !is_root_cache(cachep))
-		return ret;
-
-	lockdep_assert_held(&slab_mutex);
-	for_each_memcg_cache(c, cachep) {
-		/* return value determined by the root cache only */
-		__do_tune_cpucache(c, limit, batchcount, shared, gfp);
-	}
-
-	return ret;
-}
-
-/* Called with slab_mutex held always */
-static int enable_cpucache(struct kmem_cache *cachep, gfp_t gfp)
-{
-	int err;
-	int limit = 0;
-	int shared = 0;
-	int batchcount = 0;
-
-	err = cache_random_seq_create(cachep, cachep->num, gfp);
-	if (err)
-		goto end;
-
-	if (!is_root_cache(cachep)) {
-		struct kmem_cache *root = memcg_root_cache(cachep);
-		limit = root->limit;
-		shared = root->shared;
-		batchcount = root->batchcount;
-	}
-
-	if (limit && shared && batchcount)
-		goto skip_setup;
-	/*
-	 * The head array serves three purposes:
-	 * - create a LIFO ordering, i.e. return objects that are cache-warm
-	 * - reduce the number of spinlock operations.
-	 * - reduce the number of linked list operations on the slab and
-	 *   bufctl chains: array operations are cheaper.
-	 * The numbers are guessed, we should auto-tune as described by
-	 * Bonwick.
-	 */
-	if (cachep->size > 131072)
-		limit = 1;
-	else if (cachep->size > PAGE_SIZE)
-		limit = 8;
-	else if (cachep->size > 1024)
-		limit = 24;
-	else if (cachep->size > 256)
-		limit = 54;
-	else
-		limit = 120;
-
-	/*
-	 * CPU bound tasks (e.g. network routing) can exhibit cpu bound
-	 * allocation behaviour: Most allocs on one cpu, most free operations
-	 * on another cpu. For these cases, an efficient object passing between
-	 * cpus is necessary. This is provided by a shared array. The array
-	 * replaces Bonwick's magazine layer.
-	 * On uniprocessor, it's functionally equivalent (but less efficient)
-	 * to a larger limit. Thus disabled by default.
-	 */
-	shared = 0;
-	if (cachep->size <= PAGE_SIZE && num_possible_cpus() > 1)
-		shared = 8;
-
-#if DEBUG
-	/*
-	 * With debugging enabled, large batchcount lead to excessively long
-	 * periods with disabled local interrupts. Limit the batchcount
-	 */
-	if (limit > 32)
-		limit = 32;
-#endif
-	batchcount = (limit + 1) / 2;
-skip_setup:
-	err = do_tune_cpucache(cachep, limit, batchcount, shared, gfp);
-end:
-	if (err)
-		pr_err("enable_cpucache failed for %s, error %d\n",
-		       cachep->name, -err);
-	return err;
-}
-
-/*
- * Drain an array if it contains any elements taking the node lock only if
- * necessary. Note that the node listlock also protects the array_cache
- * if drain_array() is used on the shared array.
- */
-static void drain_array(struct kmem_cache *cachep, struct kmem_cache_node *n,
-			 struct array_cache *ac, int node)
-{
-	LIST_HEAD(list);
-
-	/* ac from n->shared can be freed if we don't hold the slab_mutex. */
-	check_mutex_acquired();
-
-	if (!ac || !ac->avail)
-		return;
-
-	if (ac->touched) {
-		ac->touched = 0;
-		return;
-	}
-
-	spin_lock_irq(&n->list_lock);
-	drain_array_locked(cachep, ac, node, false, &list);
-	spin_unlock_irq(&n->list_lock);
-
-	slabs_destroy(cachep, &list);
-}
-
-/**
- * cache_reap - Reclaim memory from caches.
- * @w: work descriptor
- *
- * Called from workqueue/eventd every few seconds.
- * Purpose:
- * - clear the per-cpu caches for this CPU.
- * - return freeable pages to the main free memory pool.
- *
- * If we cannot acquire the cache chain mutex then just give up - we'll try
- * again on the next iteration.
- */
-static void cache_reap(struct work_struct *w)
-{
-	struct kmem_cache *searchp;
-	struct kmem_cache_node *n;
-	int node = numa_mem_id();
-	struct delayed_work *work = to_delayed_work(w);
-
-	if (!mutex_trylock(&slab_mutex))
-		/* Give up. Setup the next iteration. */
-		goto out;
-
-	list_for_each_entry(searchp, &slab_caches, list) {
-		check_irq_on();
-
-		/*
-		 * We only take the node lock if absolutely necessary and we
-		 * have established with reasonable certainty that
-		 * we can do some work if the lock was obtained.
-		 */
-		n = get_node(searchp, node);
-
-		reap_alien(searchp, n);
-
-		drain_array(searchp, n, cpu_cache_get(searchp), node);
-
-		/*
-		 * These are racy checks but it does not matter
-		 * if we skip one check or scan twice.
-		 */
-		if (time_after(n->next_reap, jiffies))
-			goto next;
-
-		n->next_reap = jiffies + REAPTIMEOUT_NODE;
-
-		drain_array(searchp, n, n->shared, node);
-
-		if (n->free_touched)
-			n->free_touched = 0;
-		else {
-			int freed;
-
-			freed = drain_freelist(searchp, n, (n->free_limit +
-				5 * searchp->num - 1) / (5 * searchp->num));
-			STATS_ADD_REAPED(searchp, freed);
-		}
-next:
-		cond_resched();
-	}
-	check_irq_on();
-	mutex_unlock(&slab_mutex);
-	next_reap_node();
-out:
-	/* Set up the next iteration */
-	schedule_delayed_work_on(smp_processor_id(), work,
-				round_jiffies_relative(REAPTIMEOUT_AC));
-}
-
-void get_slabinfo(struct kmem_cache *cachep, struct slabinfo *sinfo)
-{
-	unsigned long active_objs, num_objs, active_slabs;
-	unsigned long total_slabs = 0, free_objs = 0, shared_avail = 0;
-	unsigned long free_slabs = 0;
-	int node;
-	struct kmem_cache_node *n;
-
-	for_each_kmem_cache_node(cachep, node, n) {
-		check_irq_on();
-		spin_lock_irq(&n->list_lock);
-
-		total_slabs += n->total_slabs;
-		free_slabs += n->free_slabs;
-		free_objs += n->free_objects;
-
-		if (n->shared)
-			shared_avail += n->shared->avail;
-
-		spin_unlock_irq(&n->list_lock);
-	}
-	num_objs = total_slabs * cachep->num;
-	active_slabs = total_slabs - free_slabs;
-	active_objs = num_objs - free_objs;
-
-	sinfo->active_objs = active_objs;
-	sinfo->num_objs = num_objs;
-	sinfo->active_slabs = active_slabs;
-	sinfo->num_slabs = total_slabs;
-	sinfo->shared_avail = shared_avail;
-	sinfo->limit = cachep->limit;
-	sinfo->batchcount = cachep->batchcount;
-	sinfo->shared = cachep->shared;
-	sinfo->objects_per_slab = cachep->num;
-	sinfo->cache_order = cachep->gfporder;
-}
-
-void slabinfo_show_stats(struct seq_file *m, struct kmem_cache *cachep)
-{
-#if STATS
-	{			/* node stats */
-		unsigned long high = cachep->high_mark;
-		unsigned long allocs = cachep->num_allocations;
-		unsigned long grown = cachep->grown;
-		unsigned long reaped = cachep->reaped;
-		unsigned long errors = cachep->errors;
-		unsigned long max_freeable = cachep->max_freeable;
-		unsigned long node_allocs = cachep->node_allocs;
-		unsigned long node_frees = cachep->node_frees;
-		unsigned long overflows = cachep->node_overflow;
-
-		seq_printf(m, " : globalstat %7lu %6lu %5lu %4lu %4lu %4lu %4lu %4lu %4lu",
-			   allocs, high, grown,
-			   reaped, errors, max_freeable, node_allocs,
-			   node_frees, overflows);
-	}
-	/* cpu stats */
-	{
-		unsigned long allochit = atomic_read(&cachep->allochit);
-		unsigned long allocmiss = atomic_read(&cachep->allocmiss);
-		unsigned long freehit = atomic_read(&cachep->freehit);
-		unsigned long freemiss = atomic_read(&cachep->freemiss);
-
-		seq_printf(m, " : cpustat %6lu %6lu %6lu %6lu",
-			   allochit, allocmiss, freehit, freemiss);
-	}
-#endif
-}
-
-#define MAX_SLABINFO_WRITE 128
-/**
- * slabinfo_write - Tuning for the slab allocator
- * @file: unused
- * @buffer: user buffer
- * @count: data length
- * @ppos: unused
- *
- * Return: %0 on success, negative error code otherwise.
- */
-ssize_t slabinfo_write(struct file *file, const char __user *buffer,
-		       size_t count, loff_t *ppos)
-{
-	char kbuf[MAX_SLABINFO_WRITE + 1], *tmp;
-	int limit, batchcount, shared, res;
-	struct kmem_cache *cachep;
-
-	if (count > MAX_SLABINFO_WRITE)
-		return -EINVAL;
-	if (copy_from_user(&kbuf, buffer, count))
-		return -EFAULT;
-	kbuf[MAX_SLABINFO_WRITE] = '\0';
-
-	tmp = strchr(kbuf, ' ');
-	if (!tmp)
-		return -EINVAL;
-	*tmp = '\0';
-	tmp++;
-	if (sscanf(tmp, " %d %d %d", &limit, &batchcount, &shared) != 3)
-		return -EINVAL;
-
-	/* Find the cache in the chain of caches. */
-	mutex_lock(&slab_mutex);
-	res = -EINVAL;
-	list_for_each_entry(cachep, &slab_caches, list) {
-		if (!strcmp(cachep->name, kbuf)) {
-			if (limit < 1 || batchcount < 1 ||
-					batchcount > limit || shared < 0) {
-				res = 0;
-			} else {
-				res = do_tune_cpucache(cachep, limit,
-						       batchcount, shared,
-						       GFP_KERNEL);
-			}
-			break;
-		}
-	}
-	mutex_unlock(&slab_mutex);
-	if (res >= 0)
-		res = count;
-	return res;
-}
-
-#ifdef CONFIG_DEBUG_SLAB_LEAK
-
-static inline int add_caller(unsigned long *n, unsigned long v)
-{
-	unsigned long *p;
-	int l;
-	if (!v)
-		return 1;
-	l = n[1];
-	p = n + 2;
-	while (l) {
-		int i = l/2;
-		unsigned long *q = p + 2 * i;
-		if (*q == v) {
-			q[1]++;
-			return 1;
-		}
-		if (*q > v) {
-			l = i;
-		} else {
-			p = q + 2;
-			l -= i + 1;
-		}
-	}
-	if (++n[1] == n[0])
-		return 0;
-	memmove(p + 2, p, n[1] * 2 * sizeof(unsigned long) - ((void *)p - (void *)n));
-	p[0] = v;
-	p[1] = 1;
-	return 1;
-}
-
-static void handle_slab(unsigned long *n, struct kmem_cache *c,
-						struct page *page)
-{
-	void *p;
-	int i, j;
-	unsigned long v;
-
-	if (n[0] == n[1])
-		return;
-	for (i = 0, p = page->s_mem; i < c->num; i++, p += c->size) {
-		bool active = true;
-
-		for (j = page->active; j < c->num; j++) {
-			if (get_free_obj(page, j) == i) {
-				active = false;
-				break;
-			}
-		}
-
-		if (!active)
-			continue;
-
-		/*
-		 * probe_kernel_read() is used for DEBUG_PAGEALLOC. page table
-		 * mapping is established when actual object allocation and
-		 * we could mistakenly access the unmapped object in the cpu
-		 * cache.
-		 */
-		if (probe_kernel_read(&v, dbg_userword(c, p), sizeof(v)))
-			continue;
-
-		if (!add_caller(n, v))
-			return;
-	}
-}
-
-static void show_symbol(struct seq_file *m, unsigned long address)
-{
-#ifdef CONFIG_KALLSYMS
-	unsigned long offset, size;
-	char modname[MODULE_NAME_LEN], name[KSYM_NAME_LEN];
-
-	if (lookup_symbol_attrs(address, &size, &offset, modname, name) == 0) {
-		seq_printf(m, "%s+%#lx/%#lx", name, offset, size);
-		if (modname[0])
-			seq_printf(m, " [%s]", modname);
-		return;
-	}
-#endif
-	seq_printf(m, "%px", (void *)address);
-}
-
-static int leaks_show(struct seq_file *m, void *p)
-{
-	struct kmem_cache *cachep = list_entry(p, struct kmem_cache, list);
-	struct page *page;
-	struct kmem_cache_node *n;
-	const char *name;
-	unsigned long *x = m->private;
-	int node;
-	int i;
-
-	if (!(cachep->flags & SLAB_STORE_USER))
-		return 0;
-	if (!(cachep->flags & SLAB_RED_ZONE))
-		return 0;
-
-	/*
-	 * Set store_user_clean and start to grab stored user information
-	 * for all objects on this cache. If some alloc/free requests comes
-	 * during the processing, information would be wrong so restart
-	 * whole processing.
-	 */
-	do {
-		set_store_user_clean(cachep);
-		drain_cpu_caches(cachep);
-
-		x[1] = 0;
-
-		for_each_kmem_cache_node(cachep, node, n) {
-
-			check_irq_on();
-			spin_lock_irq(&n->list_lock);
-
-			list_for_each_entry(page, &n->slabs_full, lru)
-				handle_slab(x, cachep, page);
-			list_for_each_entry(page, &n->slabs_partial, lru)
-				handle_slab(x, cachep, page);
-			spin_unlock_irq(&n->list_lock);
-		}
-	} while (!is_store_user_clean(cachep));
-
-	name = cachep->name;
-	if (x[0] == x[1]) {
-		/* Increase the buffer size */
-		mutex_unlock(&slab_mutex);
-		m->private = kcalloc(x[0] * 4, sizeof(unsigned long),
-				     GFP_KERNEL);
-		if (!m->private) {
-			/* Too bad, we are really out */
-			m->private = x;
-			mutex_lock(&slab_mutex);
-			return -ENOMEM;
-		}
-		*(unsigned long *)m->private = x[0] * 2;
-		kfree(x);
-		mutex_lock(&slab_mutex);
-		/* Now make sure this entry will be retried */
-		m->count = m->size;
-		return 0;
-	}
-	for (i = 0; i < x[1]; i++) {
-		seq_printf(m, "%s: %lu ", name, x[2*i+3]);
-		show_symbol(m, x[2*i+2]);
-		seq_putc(m, '\n');
-	}
-
-	return 0;
-}
-
-static const struct seq_operations slabstats_op = {
-	.start = slab_start,
-	.next = slab_next,
-	.stop = slab_stop,
-	.show = leaks_show,
-};
-
-static int slabstats_open(struct inode *inode, struct file *file)
-{
-	unsigned long *n;
-
-	n = __seq_open_private(file, &slabstats_op, PAGE_SIZE);
-	if (!n)
-		return -ENOMEM;
-
-	*n = PAGE_SIZE / (2 * sizeof(unsigned long));
-
-	return 0;
-}
-
-static const struct file_operations proc_slabstats_operations = {
-	.open		= slabstats_open,
-	.read		= seq_read,
-	.llseek		= seq_lseek,
-	.release	= seq_release_private,
-};
-#endif
-
-static int __init slab_proc_init(void)
-{
-#ifdef CONFIG_DEBUG_SLAB_LEAK
-	proc_create("slab_allocators", 0, NULL, &proc_slabstats_operations);
-#endif
-	return 0;
-}
-module_init(slab_proc_init);
-
-#ifdef CONFIG_HARDENED_USERCOPY
-/*
- * Rejects incorrectly sized objects and objects that are to be copied
- * to/from userspace but do not fall entirely within the containing slab
- * cache's usercopy region.
- *
- * Returns NULL if check passes, otherwise const char * to name of cache
- * to indicate an error.
- */
-void __check_heap_object(const void *ptr, unsigned long n, struct page *page,
-			 bool to_user)
-{
-	struct kmem_cache *cachep;
-	unsigned int objnr;
-	unsigned long offset;
-
-	ptr = kasan_reset_tag(ptr);
-
-	/* Find and validate object. */
-	cachep = page->slab_cache;
-	objnr = obj_to_index(cachep, page, (void *)ptr);
-	BUG_ON(objnr >= cachep->num);
-
-	/* Find offset within object. */
-	offset = ptr - index_to_obj(cachep, page, objnr) - obj_offset(cachep);
-
-	/* Allow address range falling entirely within usercopy region. */
-	if (offset >= cachep->useroffset &&
-	    offset - cachep->useroffset <= cachep->usersize &&
-	    n <= cachep->useroffset - offset + cachep->usersize)
-		return;
-
-	/*
-	 * If the copy is still within the allocated object, produce
-	 * a warning instead of rejecting the copy. This is intended
-	 * to be a temporary method to find any missing usercopy
-	 * whitelists.
-	 */
-	if (usercopy_fallback &&
-	    offset <= cachep->object_size &&
-	    n <= cachep->object_size - offset) {
-		usercopy_warn("SLAB object", cachep->name, to_user, offset, n);
-		return;
-	}
-
-	usercopy_abort("SLAB object", cachep->name, to_user, offset, n);
-}
-#endif /* CONFIG_HARDENED_USERCOPY */
-
-/**
- * ksize - get the actual amount of memory allocated for a given object
- * @objp: Pointer to the object
- *
- * kmalloc may internally round up allocations and return more memory
- * than requested. ksize() can be used to determine the actual amount of
- * memory allocated. The caller may use this additional memory, even though
- * a smaller amount of memory was initially specified with the kmalloc call.
- * The caller must guarantee that objp points to a valid object previously
- * allocated with either kmalloc() or kmem_cache_alloc(). The object
- * must not be freed during the duration of the call.
- *
- * Return: size of the actual memory used by @objp in bytes
- */
-size_t ksize(const void *objp)
-{
-	size_t size;
-
-	BUG_ON(!objp);
-	if (unlikely(objp == ZERO_SIZE_PTR))
-		return 0;
-
-	size = virt_to_cache(objp)->object_size;
-	/* We assume that ksize callers could use the whole allocated area,
-	 * so we need to unpoison this area.
-	 */
-	kasan_unpoison_shadow(objp, size);
-
-	return size;
-}
-EXPORT_SYMBOL(ksize);
diff --git a/mm/slab.h b/mm/slab.h
index 43ac818b8592..d7cc432a3911 100644
--- a/mm/slab.h
+++ b/mm/slab.h
@@ -32,10 +32,6 @@ struct kmem_cache {
 
 #endif /* CONFIG_SLOB */
 
-#ifdef CONFIG_SLAB
-#include <linux/slab_def.h>
-#endif
-
 #ifdef CONFIG_SLUB
 #include <linux/slub_def.h>
 #endif
@@ -131,20 +127,14 @@ static inline slab_flags_t kmem_cache_flags(unsigned int object_size,
 			 SLAB_CACHE_DMA32 | SLAB_PANIC | \
 			 SLAB_TYPESAFE_BY_RCU | SLAB_DEBUG_OBJECTS )
 
-#if defined(CONFIG_DEBUG_SLAB)
-#define SLAB_DEBUG_FLAGS (SLAB_RED_ZONE | SLAB_POISON | SLAB_STORE_USER)
-#elif defined(CONFIG_SLUB_DEBUG)
+#if defined(CONFIG_SLUB_DEBUG)
 #define SLAB_DEBUG_FLAGS (SLAB_RED_ZONE | SLAB_POISON | SLAB_STORE_USER | \
 			  SLAB_TRACE | SLAB_CONSISTENCY_CHECKS)
 #else
 #define SLAB_DEBUG_FLAGS (0)
 #endif
 
-#if defined(CONFIG_SLAB)
-#define SLAB_CACHE_FLAGS (SLAB_MEM_SPREAD | SLAB_NOLEAKTRACE | \
-			  SLAB_RECLAIM_ACCOUNT | SLAB_TEMPORARY | \
-			  SLAB_ACCOUNT)
-#elif defined(CONFIG_SLUB)
+#if defined(CONFIG_SLUB)
 #define SLAB_CACHE_FLAGS (SLAB_NOLEAKTRACE | SLAB_RECLAIM_ACCOUNT | \
 			  SLAB_TEMPORARY | SLAB_ACCOUNT)
 #else
@@ -451,21 +441,6 @@ static inline void slab_post_alloc_hook(struct kmem_cache *s, gfp_t flags,
 struct kmem_cache_node {
 	spinlock_t list_lock;
 
-#ifdef CONFIG_SLAB
-	struct list_head slabs_partial;	/* partial list first, better asm code */
-	struct list_head slabs_full;
-	struct list_head slabs_free;
-	unsigned long total_slabs;	/* length of all slab lists */
-	unsigned long free_slabs;	/* length of free slab list only */
-	unsigned long free_objects;
-	unsigned int free_limit;
-	unsigned int colour_next;	/* Per-node cache coloring */
-	struct array_cache *shared;	/* shared per node */
-	struct alien_cache **alien;	/* on other nodes */
-	unsigned long next_reap;	/* updated without locking */
-	int free_touched;		/* updated without locking */
-#endif
-
 #ifdef CONFIG_SLUB
 	unsigned long nr_partial;
 	struct list_head partial;
@@ -501,7 +476,7 @@ void *memcg_slab_next(struct seq_file *m, void *p, loff_t *pos);
 void memcg_slab_stop(struct seq_file *m, void *p);
 int memcg_slab_show(struct seq_file *m, void *p);
 
-#if defined(CONFIG_SLAB) || defined(CONFIG_SLUB_DEBUG)
+#if defined(CONFIG_SLUB_DEBUG)
 void dump_unreclaimable_slab(void);
 #else
 static inline void dump_unreclaimable_slab(void)
diff --git a/mm/slab_common.c b/mm/slab_common.c
index 58251ba63e4a..dbefc8ef5fbf 100644
--- a/mm/slab_common.c
+++ b/mm/slab_common.c
@@ -351,10 +351,6 @@ struct kmem_cache *find_mergeable(unsigned int size, unsigned int align,
 		if (s->size - size >= sizeof(void *))
 			continue;
 
-		if (IS_ENABLED(CONFIG_SLAB) && align &&
-			(align > s->align || s->align % align))
-			continue;
-
 		return s;
 	}
 	return NULL;
@@ -1294,12 +1290,8 @@ void cache_random_seq_destroy(struct kmem_cache *cachep)
 }
 #endif /* CONFIG_SLAB_FREELIST_RANDOM */
 
-#if defined(CONFIG_SLAB) || defined(CONFIG_SLUB_DEBUG)
-#ifdef CONFIG_SLAB
-#define SLABINFO_RIGHTS (0600)
-#else
+#ifdef CONFIG_SLUB_DEBUG
 #define SLABINFO_RIGHTS (0400)
-#endif
 
 static void print_slabinfo_header(struct seq_file *m)
 {
@@ -1307,18 +1299,10 @@ static void print_slabinfo_header(struct seq_file *m)
 	 * Output format version, so at least we can change it
 	 * without _too_ many complaints.
 	 */
-#ifdef CONFIG_DEBUG_SLAB
-	seq_puts(m, "slabinfo - version: 2.1 (statistics)\n");
-#else
 	seq_puts(m, "slabinfo - version: 2.1\n");
-#endif
 	seq_puts(m, "# name            <active_objs> <num_objs> <objsize> <objperslab> <pagesperslab>");
 	seq_puts(m, " : tunables <limit> <batchcount> <sharedfactor>");
 	seq_puts(m, " : slabdata <active_slabs> <num_slabs> <sharedavail>");
-#ifdef CONFIG_DEBUG_SLAB
-	seq_puts(m, " : globalstat <listallocs> <maxobjs> <grown> <reaped> <error> <maxfreeable> <nodeallocs> <remotefrees> <alienoverflow>");
-	seq_puts(m, " : cpustat <allochit> <allocmiss> <freehit> <freemiss>");
-#endif
 	seq_putc(m, '\n');
 }
 
@@ -1498,7 +1482,7 @@ static int __init slab_proc_init(void)
 	return 0;
 }
 module_init(slab_proc_init);
-#endif /* CONFIG_SLAB || CONFIG_SLUB_DEBUG */
+#endif /* CONFIG_SLUB_DEBUG */
 
 static __always_inline void *__do_krealloc(const void *p, size_t new_size,
 					   gfp_t flags)
-- 
2.21.0

Re: [PATCH 0/1] mm: Remove the SLAB allocator

[Vlastimil Babka]

On 4/10/19 4:47 AM, Tobin C. Harding wrote:
> Recently a 2 year old bug was found in the SLAB allocator that crashes
> the kernel.  This seems to imply that not that many people are using the
> SLAB allocator.

AFAIK that bug required CONFIG_DEBUG_SLAB_LEAK, not just SLAB. That
seems to imply not that many people are using SLAB when debugging and
yeah, SLUB has better debugging support. But I wouldn't dare to make the
broader implication :)

> Currently we have 3 slab allocators.  Two is company three is a crowd -
> let's get rid of one. 
> 
>  - The SLUB allocator has been the default since 2.6.23

Yeah, with a sophisticated reasoning :)
https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=a0acd820807680d2ccc4ef3448387fcdbf152c73

>  - The SLOB allocator is kinda sexy.  Its only 664 LOC, the general
>    design is outlined in KnR, and there is an optimisation taken from
>    Knuth - say no more.
> 
> If you are using the SLAB allocator please speak now or forever hold your peace ...

FWIW, our enterprise kernel use it (latest is 4.12 based), and openSUSE
kernels as well (with openSUSE Tumbleweed that includes latest
kernel.org stables). AFAIK we don't enable SLAB_DEBUG even in general
debug kernel flavours as it's just too slow.

IIRC last time Mel evaluated switching to SLUB, it wasn't a clear
winner, but I'll just CC him for details :)

> Testing:
> 
> Build kernel with `make defconfig` (on x86_64 machine) followed by `make
> kvmconfig`.  Then do the same and manually select SLOB.  Boot both
> kernels in Qemu.
> 
> 
> thanks,
> Tobin.
> 
> 
> Tobin C. Harding (1):
>   mm: Remove SLAB allocator
> 
>  include/linux/slab.h |   26 -
>  kernel/cpu.c         |    5 -
>  mm/slab.c            | 4493 ------------------------------------------
>  mm/slab.h            |   31 +-
>  mm/slab_common.c     |   20 +-
>  5 files changed, 5 insertions(+), 4570 deletions(-)
>  delete mode 100644 mm/slab.c
> 

Re: [PATCH 0/1] mm: Remove the SLAB allocator

[Tobin C. Harding]

On Wed, Apr 10, 2019 at 10:02:36AM +0200, Vlastimil Babka wrote:
> On 4/10/19 4:47 AM, Tobin C. Harding wrote:
> > Recently a 2 year old bug was found in the SLAB allocator that crashes
> > the kernel.  This seems to imply that not that many people are using the
> > SLAB allocator.
> 
> AFAIK that bug required CONFIG_DEBUG_SLAB_LEAK, not just SLAB. That
> seems to imply not that many people are using SLAB when debugging and
> yeah, SLUB has better debugging support. But I wouldn't dare to make the
> broader implication :)

Point noted.

> > Currently we have 3 slab allocators.  Two is company three is a crowd -
> > let's get rid of one. 
> > 
> >  - The SLUB allocator has been the default since 2.6.23
> 
> Yeah, with a sophisticated reasoning :)
> https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=a0acd820807680d2ccc4ef3448387fcdbf152c73
> 
> >  - The SLOB allocator is kinda sexy.  Its only 664 LOC, the general
> >    design is outlined in KnR, and there is an optimisation taken from
> >    Knuth - say no more.
> > 
> > If you are using the SLAB allocator please speak now or forever hold your peace ...
> 
> FWIW, our enterprise kernel use it (latest is 4.12 based), and openSUSE
> kernels as well (with openSUSE Tumbleweed that includes latest
> kernel.org stables). AFAIK we don't enable SLAB_DEBUG even in general
> debug kernel flavours as it's just too slow.

Ok, so that probably already kills this.  Thanks for the response.  No
flaming, no swearing, man! and they said LKML was a harsh environment ...

> IIRC last time Mel evaluated switching to SLUB, it wasn't a clear
> winner, but I'll just CC him for details :)

Probably don't need to take up too much of Mel's time, if we have one
user in production we have to keep it, right.

Thanks for your time Vlastimil.


	Tobin

Re: [PATCH 0/1] mm: Remove the SLAB allocator

[Michal Hocko]

On Wed 10-04-19 18:16:18, Tobin C. Harding wrote:
> On Wed, Apr 10, 2019 at 10:02:36AM +0200, Vlastimil Babka wrote:
> > On 4/10/19 4:47 AM, Tobin C. Harding wrote:
> > > Recently a 2 year old bug was found in the SLAB allocator that crashes
> > > the kernel.  This seems to imply that not that many people are using the
> > > SLAB allocator.
> > 
> > AFAIK that bug required CONFIG_DEBUG_SLAB_LEAK, not just SLAB. That
> > seems to imply not that many people are using SLAB when debugging and
> > yeah, SLUB has better debugging support. But I wouldn't dare to make the
> > broader implication :)
> 
> Point noted.
> 
> > > Currently we have 3 slab allocators.  Two is company three is a crowd -
> > > let's get rid of one. 
> > > 
> > >  - The SLUB allocator has been the default since 2.6.23
> > 
> > Yeah, with a sophisticated reasoning :)
> > https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=a0acd820807680d2ccc4ef3448387fcdbf152c73
> > 
> > >  - The SLOB allocator is kinda sexy.  Its only 664 LOC, the general
> > >    design is outlined in KnR, and there is an optimisation taken from
> > >    Knuth - say no more.
> > > 
> > > If you are using the SLAB allocator please speak now or forever hold your peace ...
> > 
> > FWIW, our enterprise kernel use it (latest is 4.12 based), and openSUSE
> > kernels as well (with openSUSE Tumbleweed that includes latest
> > kernel.org stables). AFAIK we don't enable SLAB_DEBUG even in general
> > debug kernel flavours as it's just too slow.
> 
> Ok, so that probably already kills this.  Thanks for the response.  No
> flaming, no swearing, man! and they said LKML was a harsh environment ...
> 
> > IIRC last time Mel evaluated switching to SLUB, it wasn't a clear
> > winner, but I'll just CC him for details :)
> 
> Probably don't need to take up too much of Mel's time, if we have one
> user in production we have to keep it, right.

Well, I wouldn't be opposed to dropping SLAB. Especially when this is
not a longterm stable kmalloc implementation anymore. It turned out that
people want to push features from SLUB back to SLAB and then we are just
having two featurefull allocators and double the maintenance cost.

So as long as the performance gap is no longer there and the last data
from Mel (I am sorry but I cannot find a link handy) suggests that there
is no overall winner in benchmarks then why to keep them both?

That being said, if somebody is willing to go and benchmark both
allocators to confirm Mel's observations and current users of SLAB
can confirm their workloads do not regress either then let's just drop
it.

Please please have it more rigorous then what happened when SLUB was
forced to become a default
-- 
Michal Hocko
SUSE Labs

Re: [PATCH 0/1] mm: Remove the SLAB allocator

[Pekka Enberg]

Hi,

On 4/11/19 10:55 AM, Michal Hocko wrote:
> Please please have it more rigorous then what happened when SLUB was
> forced to become a default

This is the hard part.

Even if you are able to show that SLUB is as fast as SLAB for all the 
benchmarks you run, there's bound to be that one workload where SLUB 
regresses. You will then have people complaining about that (rightly so) 
and you're again stuck with two allocators.

To move forward, I think we should look at possible *pathological* cases 
where we think SLAB might have an advantage. For example, SLUB had much 
more difficulties with remote CPU frees than SLAB. Now I don't know if 
this is the case, but it should be easy to construct a synthetic 
benchmark to measure this.

For example, have a userspace process that does networking, which is 
often memory allocation intensive, so that we know that SKBs traverse 
between CPUs. You can do this by making sure that the NIC queues are 
mapped to CPU N (so that network softirqs have to run on that CPU) but 
the process is pinned to CPU M.

It's, of course, worth thinking about other pathological cases too. 
Workloads that cause large allocations is one. Workloads that cause lots 
of slab cache shrinking is another.

- Pekka

Re: [PATCH 0/1] mm: Remove the SLAB allocator

[Jesper Dangaard Brouer]

On Thu, 11 Apr 2019 11:27:26 +0300
Pekka Enberg <penberg@iki.fi> wrote:

> Hi,
> 
> On 4/11/19 10:55 AM, Michal Hocko wrote:
> > Please please have it more rigorous then what happened when SLUB was
> > forced to become a default  
> 
> This is the hard part.
> 
> Even if you are able to show that SLUB is as fast as SLAB for all the 
> benchmarks you run, there's bound to be that one workload where SLUB 
> regresses. You will then have people complaining about that (rightly so) 
> and you're again stuck with two allocators.
> 
> To move forward, I think we should look at possible *pathological* cases 
> where we think SLAB might have an advantage. For example, SLUB had much 
> more difficulties with remote CPU frees than SLAB. Now I don't know if 
> this is the case, but it should be easy to construct a synthetic 
> benchmark to measure this.

I do think SLUB have a number of pathological cases where SLAB is
faster.  If was significantly more difficult to get good bulk-free
performance for SLUB.  SLUB is only fast as long as objects belong to
the same page.  To get good bulk-free performance if objects are
"mixed", I coded this[1] way-too-complex fast-path code to counter
act this (joined work with Alex Duyck).

[1] https://github.com/torvalds/linux/blob/v5.1-rc5/mm/slub.c#L3033-L3113


> For example, have a userspace process that does networking, which is 
> often memory allocation intensive, so that we know that SKBs traverse 
> between CPUs. You can do this by making sure that the NIC queues are 
> mapped to CPU N (so that network softirqs have to run on that CPU) but 
> the process is pinned to CPU M.

If someone want to test this with SKBs then be-aware that we netdev-guys
have a number of optimizations where we try to counter act this. (As
minimum disable TSO and GRO).

It might also be possible for people to get inspired by and adapt the
micro benchmarking[2] kernel modules that I wrote when developing the
SLUB and SLAB optimizations:

[2] https://github.com/netoptimizer/prototype-kernel/tree/master/kernel/mm


> It's, of course, worth thinking about other pathological cases too. 
> Workloads that cause large allocations is one. Workloads that cause lots 
> of slab cache shrinking is another.

I also worry about long uptimes when SLUB objects/pages gets too
fragmented... as I said SLUB is only efficient when objects are
returned to the same page, while SLAB is not.


I did a comparison of bulk FREE performance here (where SLAB is
slightly faster):
 Commit ca257195511d ("mm: new API kfree_bulk() for SLAB+SLUB allocators")
 [3] https://git.kernel.org/torvalds/c/ca257195511d

You might also notice how simple the SLAB code is:
  Commit e6cdb58d1c83 ("slab: implement bulk free in SLAB allocator")
  [4] https://git.kernel.org/torvalds/c/e6cdb58d1c83


-- 
Best regards,
  Jesper Dangaard Brouer
  MSc.CS, Principal Kernel Engineer at Red Hat
  LinkedIn: http://www.linkedin.com/in/brouer

Re: [PATCH 0/1] mm: Remove the SLAB allocator

[Christopher Lameter]

On Wed, 17 Apr 2019, Jesper Dangaard Brouer wrote:

> I do think SLUB have a number of pathological cases where SLAB is
> faster.  If was significantly more difficult to get good bulk-free
> performance for SLUB.  SLUB is only fast as long as objects belong to
> the same page.  To get good bulk-free performance if objects are
> "mixed", I coded this[1] way-too-complex fast-path code to counter
> act this (joined work with Alex Duyck).

Right. SLUB usually compensates for that with superior allocation
performance.

> > It's, of course, worth thinking about other pathological cases too.
> > Workloads that cause large allocations is one. Workloads that cause lots
> > of slab cache shrinking is another.
>
> I also worry about long uptimes when SLUB objects/pages gets too
> fragmented... as I said SLUB is only efficient when objects are
> returned to the same page, while SLAB is not.

??? Why would SLUB pages get more fragmented? SLUB has fragmentation
prevention methods that SLAB does not have.

Re: [PATCH 0/1] mm: Remove the SLAB allocator

[Michal Hocko]

On Wed 17-04-19 10:50:18, Jesper Dangaard Brouer wrote:
> On Thu, 11 Apr 2019 11:27:26 +0300
> Pekka Enberg <penberg@iki.fi> wrote:
> 
> > Hi,
> > 
> > On 4/11/19 10:55 AM, Michal Hocko wrote:
> > > Please please have it more rigorous then what happened when SLUB was
> > > forced to become a default  
> > 
> > This is the hard part.
> > 
> > Even if you are able to show that SLUB is as fast as SLAB for all the 
> > benchmarks you run, there's bound to be that one workload where SLUB 
> > regresses. You will then have people complaining about that (rightly so) 
> > and you're again stuck with two allocators.
> > 
> > To move forward, I think we should look at possible *pathological* cases 
> > where we think SLAB might have an advantage. For example, SLUB had much 
> > more difficulties with remote CPU frees than SLAB. Now I don't know if 
> > this is the case, but it should be easy to construct a synthetic 
> > benchmark to measure this.
> 
> I do think SLUB have a number of pathological cases where SLAB is
> faster.  If was significantly more difficult to get good bulk-free
> performance for SLUB.  SLUB is only fast as long as objects belong to
> the same page.  To get good bulk-free performance if objects are
> "mixed", I coded this[1] way-too-complex fast-path code to counter
> act this (joined work with Alex Duyck).
> 
> [1] https://github.com/torvalds/linux/blob/v5.1-rc5/mm/slub.c#L3033-L3113

How often is this a real problem for real workloads?

> > For example, have a userspace process that does networking, which is 
> > often memory allocation intensive, so that we know that SKBs traverse 
> > between CPUs. You can do this by making sure that the NIC queues are 
> > mapped to CPU N (so that network softirqs have to run on that CPU) but 
> > the process is pinned to CPU M.
> 
> If someone want to test this with SKBs then be-aware that we netdev-guys
> have a number of optimizations where we try to counter act this. (As
> minimum disable TSO and GRO).
> 
> It might also be possible for people to get inspired by and adapt the
> micro benchmarking[2] kernel modules that I wrote when developing the
> SLUB and SLAB optimizations:
> 
> [2] https://github.com/netoptimizer/prototype-kernel/tree/master/kernel/mm

While microbenchmarks are good to see pathological behavior, I would be
really interested to see some numbers for real world usecases.
 
> > It's, of course, worth thinking about other pathological cases too. 
> > Workloads that cause large allocations is one. Workloads that cause lots 
> > of slab cache shrinking is another.
> 
> I also worry about long uptimes when SLUB objects/pages gets too
> fragmented... as I said SLUB is only efficient when objects are
> returned to the same page, while SLAB is not.

Is this something that has been actually measured in a real deployment?
-- 
Michal Hocko
SUSE Labs

Re: [PATCH 0/1] mm: Remove the SLAB allocator

[Jesper Dangaard Brouer]

On Wed, 17 Apr 2019 15:38:52 +0200
Michal Hocko <mhocko@kernel.org> wrote:

> On Wed 17-04-19 10:50:18, Jesper Dangaard Brouer wrote:
> > On Thu, 11 Apr 2019 11:27:26 +0300
> > Pekka Enberg <penberg@iki.fi> wrote:
> >   
> > > Hi,
> > > 
> > > On 4/11/19 10:55 AM, Michal Hocko wrote:  
> > > > Please please have it more rigorous then what happened when SLUB was
> > > > forced to become a default    
> > > 
> > > This is the hard part.
> > > 
> > > Even if you are able to show that SLUB is as fast as SLAB for all the 
> > > benchmarks you run, there's bound to be that one workload where SLUB 
> > > regresses. You will then have people complaining about that (rightly so) 
> > > and you're again stuck with two allocators.
> > > 
> > > To move forward, I think we should look at possible *pathological* cases 
> > > where we think SLAB might have an advantage. For example, SLUB had much 
> > > more difficulties with remote CPU frees than SLAB. Now I don't know if 
> > > this is the case, but it should be easy to construct a synthetic 
> > > benchmark to measure this.  
> > 
> > I do think SLUB have a number of pathological cases where SLAB is
> > faster.  If was significantly more difficult to get good bulk-free
> > performance for SLUB.  SLUB is only fast as long as objects belong to
> > the same page.  To get good bulk-free performance if objects are
> > "mixed", I coded this[1] way-too-complex fast-path code to counter
> > act this (joined work with Alex Duyck).
> > 
> > [1] https://github.com/torvalds/linux/blob/v5.1-rc5/mm/slub.c#L3033-L3113  
> 
> How often is this a real problem for real workloads?

First let me point out that I have a benchmark[2] that test this
worse-case behavior, and micro-benchmark wise it was a big win.  I did
limit the "lookahead" based on this benchmark balance/bound worse-case
behavior.

 [2] https://github.com/netoptimizer/prototype-kernel/blob/master/kernel/mm/slab_bulk_test03.c#L4-L8

Second, I do think this happens for real workloads. As production
systems will have many sockets where SKBs (SLAB objects) can be queued,
and an unpredictable traffic pattern, that could cause this "mixed"
SLAB-object from different pages. The skbuff_head_cache size is 256 and
is using a order-1 page (8192/256=) 32 objects per page.  Netstack bulk
free mostly happens from (DMA) TX completion which have ring-sizes
usually between 512 to 1024 packets, although we do limit bulk free to
64 objects.


> > > For example, have a userspace process that does networking, which is 
> > > often memory allocation intensive, so that we know that SKBs traverse 
> > > between CPUs. You can do this by making sure that the NIC queues are 
> > > mapped to CPU N (so that network softirqs have to run on that CPU) but 
> > > the process is pinned to CPU M.  
> > 
> > If someone want to test this with SKBs then be-aware that we netdev-guys
> > have a number of optimizations where we try to counter act this. (As
> > minimum disable TSO and GRO).
> > 
> > It might also be possible for people to get inspired by and adapt the
> > micro benchmarking[2] kernel modules that I wrote when developing the
> > SLUB and SLAB optimizations:
> > 
> > [2] https://github.com/netoptimizer/prototype-kernel/tree/master/kernel/mm  
> 
> While microbenchmarks are good to see pathological behavior, I would be
> really interested to see some numbers for real world usecases.

Yes, I would love to see that too, but there is a gap between kernel
developers with the knowledge to diagnose/make-sense of this, and
people running production systems...

(Cc Brendan Gregg)
Maybe we should create some tracepoints that makes it possible to
measure, e.g. how often SLUB fast-path vs slow-path is hit (or other
behavior _you_ want to know about), and then create some easy to use
trace-tools that sysadms can run.  I bet Brendan could write some
bpftrace[3] script that does this, if someone can describe what we want
to measure...

[3] https://github.com/iovisor/bpftrace

 
> > > It's, of course, worth thinking about other pathological cases too. 
> > > Workloads that cause large allocations is one. Workloads that cause lots 
> > > of slab cache shrinking is another.  
> > 
> > I also worry about long uptimes when SLUB objects/pages gets too
> > fragmented... as I said SLUB is only efficient when objects are
> > returned to the same page, while SLAB is not.  
> 
> Is this something that has been actually measured in a real deployment?

This is also something that would be interesting to have a tool for,
that can answer: how fragmented are the SLUB objects in my production
system(?)

-- 
Best regards,
  Jesper Dangaard Brouer
  MSc.CS, Principal Kernel Engineer at Red Hat
  LinkedIn: http://www.linkedin.com/in/brouer

Re: [PATCH 0/1] mm: Remove the SLAB allocator

[Mel Gorman]

On Thu, Apr 11, 2019 at 09:55:56AM +0200, Michal Hocko wrote:
> > > FWIW, our enterprise kernel use it (latest is 4.12 based), and openSUSE
> > > kernels as well (with openSUSE Tumbleweed that includes latest
> > > kernel.org stables). AFAIK we don't enable SLAB_DEBUG even in general
> > > debug kernel flavours as it's just too slow.
> > 
> > Ok, so that probably already kills this.  Thanks for the response.  No
> > flaming, no swearing, man! and they said LKML was a harsh environment ...
> > 
> > > IIRC last time Mel evaluated switching to SLUB, it wasn't a clear
> > > winner, but I'll just CC him for details :)
> > 
> > Probably don't need to take up too much of Mel's time, if we have one
> > user in production we have to keep it, right.
> 
> Well, I wouldn't be opposed to dropping SLAB. Especially when this is
> not a longterm stable kmalloc implementation anymore. It turned out that
> people want to push features from SLUB back to SLAB and then we are just
> having two featurefull allocators and double the maintenance cost.
> 

Indeed.

> So as long as the performance gap is no longer there and the last data
> from Mel (I am sorry but I cannot find a link handy) suggests that there
> is no overall winner in benchmarks then why to keep them both?
> 

The link isn't public. It was based on kernel 5.0 but I still haven't
gotten around to doing a proper writeup. The very short summary is that
with the defaults, SLUB is either performance-neutral or a win versus slab
which is a big improvement over a few years ago. It's worth noting that
there still is a partial relianace on it using high-order pages to get
that performance. If the max order is 0 then there are cases when SLUB
is a loss *but* even that is not universal.  hackbench using processes
and sockets to communicate seems to be the hardest hit when SLUB is not
using high-order pages. This still allows the possibility that SLUB can
degrade over time if the system gets badly enough fragmented and there
are cases where kcompactd and fragmentation avoidance will be more active
than it was relative to SLAB. Again, this is much better than it was a
few years ago and I'm not aware of bug reports that point to compaction
overhead due to SLUB.

> That being said, if somebody is willing to go and benchmark both
> allocators to confirm Mel's observations and current users of SLAB
> can confirm their workloads do not regress either then let's just drop
> it.
> 

Independent verification would be nice. Of particular interest would be
a real set of networking tests on a high-speed network. The hardware in
the test grid I use doesn't have a fast enough network for me to draw a
reliable conclusion.

-- 
Mel Gorman
SUSE Labs

Re: [PATCH 0/1] mm: Remove the SLAB allocator

[David Rientjes]

On Wed, 10 Apr 2019, Vlastimil Babka wrote:

> On 4/10/19 4:47 AM, Tobin C. Harding wrote:
> > Recently a 2 year old bug was found in the SLAB allocator that crashes
> > the kernel.  This seems to imply that not that many people are using the
> > SLAB allocator.
> 
> AFAIK that bug required CONFIG_DEBUG_SLAB_LEAK, not just SLAB. That
> seems to imply not that many people are using SLAB when debugging and
> yeah, SLUB has better debugging support. But I wouldn't dare to make the
> broader implication :)
> 
> > Currently we have 3 slab allocators.  Two is company three is a crowd -
> > let's get rid of one. 
> > 
> >  - The SLUB allocator has been the default since 2.6.23
> 
> Yeah, with a sophisticated reasoning :)
> https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=a0acd820807680d2ccc4ef3448387fcdbf152c73
> 
> >  - The SLOB allocator is kinda sexy.  Its only 664 LOC, the general
> >    design is outlined in KnR, and there is an optimisation taken from
> >    Knuth - say no more.
> > 
> > If you are using the SLAB allocator please speak now or forever hold your peace ...
> 
> FWIW, our enterprise kernel use it (latest is 4.12 based), and openSUSE
> kernels as well (with openSUSE Tumbleweed that includes latest
> kernel.org stables). AFAIK we don't enable SLAB_DEBUG even in general
> debug kernel flavours as it's just too slow.
> 
> IIRC last time Mel evaluated switching to SLUB, it wasn't a clear
> winner, but I'll just CC him for details :)
> 

We also use CONFIG_SLAB and disable CONFIG_SLAB_DEBUG for the same reason.

Re: [PATCH 0/1] mm: Remove the SLAB allocator

[Mel Gorman]

On Wed, Apr 10, 2019 at 02:53:34PM -0700, David Rientjes wrote:
> > FWIW, our enterprise kernel use it (latest is 4.12 based), and openSUSE
> > kernels as well (with openSUSE Tumbleweed that includes latest
> > kernel.org stables). AFAIK we don't enable SLAB_DEBUG even in general
> > debug kernel flavours as it's just too slow.
> > 
> > IIRC last time Mel evaluated switching to SLUB, it wasn't a clear
> > winner, but I'll just CC him for details :)
> > 
> 
> We also use CONFIG_SLAB and disable CONFIG_SLAB_DEBUG for the same reason.

Would it be possible to re-evaluate using mainline kernel 5.0?

-- 
Mel Gorman
SUSE Labs

Re: [PATCH 0/1] mm: Remove the SLAB allocator

[Andrew Morton]

On Fri, 12 Apr 2019 12:28:16 +0100 Mel Gorman <mgorman@techsingularity.net> wrote:

> On Wed, Apr 10, 2019 at 02:53:34PM -0700, David Rientjes wrote:
> > > FWIW, our enterprise kernel use it (latest is 4.12 based), and openSUSE
> > > kernels as well (with openSUSE Tumbleweed that includes latest
> > > kernel.org stables). AFAIK we don't enable SLAB_DEBUG even in general
> > > debug kernel flavours as it's just too slow.
> > > 
> > > IIRC last time Mel evaluated switching to SLUB, it wasn't a clear
> > > winner, but I'll just CC him for details :)
> > > 
> > 
> > We also use CONFIG_SLAB and disable CONFIG_SLAB_DEBUG for the same reason.
> 
> Would it be possible to re-evaluate using mainline kernel 5.0?

I have vague memories that slab outperforms slub for some networking
loads.  Could the net folks please comment?