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diff --git a/sys/contrib/openzfs/module/os/linux/spl/spl-kmem-cache.c b/sys/contrib/openzfs/module/os/linux/spl/spl-kmem-cache.c
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index 000000000000..15dc27624c55
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+++ b/sys/contrib/openzfs/module/os/linux/spl/spl-kmem-cache.c
@@ -0,0 +1,1469 @@
+/*
+ * Copyright (C) 2007-2010 Lawrence Livermore National Security, LLC.
+ * Copyright (C) 2007 The Regents of the University of California.
+ * Produced at Lawrence Livermore National Laboratory (cf, DISCLAIMER).
+ * Written by Brian Behlendorf <behlendorf1@llnl.gov>.
+ * UCRL-CODE-235197
+ *
+ * This file is part of the SPL, Solaris Porting Layer.
+ * For details, see <http://zfsonlinux.org/>.
+ *
+ * The SPL is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License as published by the
+ * Free Software Foundation; either version 2 of the License, or (at your
+ * option) any later version.
+ *
+ * The SPL is distributed in the hope that it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
+ * for more details.
+ *
+ * You should have received a copy of the GNU General Public License along
+ * with the SPL. If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#include <linux/percpu_compat.h>
+#include <sys/kmem.h>
+#include <sys/kmem_cache.h>
+#include <sys/taskq.h>
+#include <sys/timer.h>
+#include <sys/vmem.h>
+#include <sys/wait.h>
+#include <linux/slab.h>
+#include <linux/swap.h>
+#include <linux/prefetch.h>
+
+/*
+ * Within the scope of spl-kmem.c file the kmem_cache_* definitions
+ * are removed to allow access to the real Linux slab allocator.
+ */
+#undef kmem_cache_destroy
+#undef kmem_cache_create
+#undef kmem_cache_alloc
+#undef kmem_cache_free
+
+
+/*
+ * Linux 3.16 replaced smp_mb__{before,after}_{atomic,clear}_{dec,inc,bit}()
+ * with smp_mb__{before,after}_atomic() because they were redundant. This is
+ * only used inside our SLAB allocator, so we implement an internal wrapper
+ * here to give us smp_mb__{before,after}_atomic() on older kernels.
+ */
+#ifndef smp_mb__before_atomic
+#define smp_mb__before_atomic(x) smp_mb__before_clear_bit(x)
+#endif
+
+#ifndef smp_mb__after_atomic
+#define smp_mb__after_atomic(x) smp_mb__after_clear_bit(x)
+#endif
+
+/* BEGIN CSTYLED */
+
+/*
+ * Cache magazines are an optimization designed to minimize the cost of
+ * allocating memory. They do this by keeping a per-cpu cache of recently
+ * freed objects, which can then be reallocated without taking a lock. This
+ * can improve performance on highly contended caches. However, because
+ * objects in magazines will prevent otherwise empty slabs from being
+ * immediately released this may not be ideal for low memory machines.
+ *
+ * For this reason spl_kmem_cache_magazine_size can be used to set a maximum
+ * magazine size. When this value is set to 0 the magazine size will be
+ * automatically determined based on the object size. Otherwise magazines
+ * will be limited to 2-256 objects per magazine (i.e per cpu). Magazines
+ * may never be entirely disabled in this implementation.
+ */
+unsigned int spl_kmem_cache_magazine_size = 0;
+module_param(spl_kmem_cache_magazine_size, uint, 0444);
+MODULE_PARM_DESC(spl_kmem_cache_magazine_size,
+ "Default magazine size (2-256), set automatically (0)");
+
+/*
+ * The default behavior is to report the number of objects remaining in the
+ * cache. This allows the Linux VM to repeatedly reclaim objects from the
+ * cache when memory is low satisfy other memory allocations. Alternately,
+ * setting this value to KMC_RECLAIM_ONCE limits how aggressively the cache
+ * is reclaimed. This may increase the likelihood of out of memory events.
+ */
+unsigned int spl_kmem_cache_reclaim = 0 /* KMC_RECLAIM_ONCE */;
+module_param(spl_kmem_cache_reclaim, uint, 0644);
+MODULE_PARM_DESC(spl_kmem_cache_reclaim, "Single reclaim pass (0x1)");
+
+unsigned int spl_kmem_cache_obj_per_slab = SPL_KMEM_CACHE_OBJ_PER_SLAB;
+module_param(spl_kmem_cache_obj_per_slab, uint, 0644);
+MODULE_PARM_DESC(spl_kmem_cache_obj_per_slab, "Number of objects per slab");
+
+unsigned int spl_kmem_cache_max_size = SPL_KMEM_CACHE_MAX_SIZE;
+module_param(spl_kmem_cache_max_size, uint, 0644);
+MODULE_PARM_DESC(spl_kmem_cache_max_size, "Maximum size of slab in MB");
+
+/*
+ * For small objects the Linux slab allocator should be used to make the most
+ * efficient use of the memory. However, large objects are not supported by
+ * the Linux slab and therefore the SPL implementation is preferred. A cutoff
+ * of 16K was determined to be optimal for architectures using 4K pages.
+ */
+#if PAGE_SIZE == 4096
+unsigned int spl_kmem_cache_slab_limit = 16384;
+#else
+unsigned int spl_kmem_cache_slab_limit = 0;
+#endif
+module_param(spl_kmem_cache_slab_limit, uint, 0644);
+MODULE_PARM_DESC(spl_kmem_cache_slab_limit,
+ "Objects less than N bytes use the Linux slab");
+
+/*
+ * The number of threads available to allocate new slabs for caches. This
+ * should not need to be tuned but it is available for performance analysis.
+ */
+unsigned int spl_kmem_cache_kmem_threads = 4;
+module_param(spl_kmem_cache_kmem_threads, uint, 0444);
+MODULE_PARM_DESC(spl_kmem_cache_kmem_threads,
+ "Number of spl_kmem_cache threads");
+/* END CSTYLED */
+
+/*
+ * Slab allocation interfaces
+ *
+ * While the Linux slab implementation was inspired by the Solaris
+ * implementation I cannot use it to emulate the Solaris APIs. I
+ * require two features which are not provided by the Linux slab.
+ *
+ * 1) Constructors AND destructors. Recent versions of the Linux
+ * kernel have removed support for destructors. This is a deal
+ * breaker for the SPL which contains particularly expensive
+ * initializers for mutex's, condition variables, etc. We also
+ * require a minimal level of cleanup for these data types unlike
+ * many Linux data types which do need to be explicitly destroyed.
+ *
+ * 2) Virtual address space backed slab. Callers of the Solaris slab
+ * expect it to work well for both small are very large allocations.
+ * Because of memory fragmentation the Linux slab which is backed
+ * by kmalloc'ed memory performs very badly when confronted with
+ * large numbers of large allocations. Basing the slab on the
+ * virtual address space removes the need for contiguous pages
+ * and greatly improve performance for large allocations.
+ *
+ * For these reasons, the SPL has its own slab implementation with
+ * the needed features. It is not as highly optimized as either the
+ * Solaris or Linux slabs, but it should get me most of what is
+ * needed until it can be optimized or obsoleted by another approach.
+ *
+ * One serious concern I do have about this method is the relatively
+ * small virtual address space on 32bit arches. This will seriously
+ * constrain the size of the slab caches and their performance.
+ */
+
+struct list_head spl_kmem_cache_list; /* List of caches */
+struct rw_semaphore spl_kmem_cache_sem; /* Cache list lock */
+taskq_t *spl_kmem_cache_taskq; /* Task queue for aging / reclaim */
+
+static void spl_cache_shrink(spl_kmem_cache_t *skc, void *obj);
+
+static void *
+kv_alloc(spl_kmem_cache_t *skc, int size, int flags)
+{
+ gfp_t lflags = kmem_flags_convert(flags);
+ void *ptr;
+
+ ptr = spl_vmalloc(size, lflags | __GFP_HIGHMEM);
+
+ /* Resulting allocated memory will be page aligned */
+ ASSERT(IS_P2ALIGNED(ptr, PAGE_SIZE));
+
+ return (ptr);
+}
+
+static void
+kv_free(spl_kmem_cache_t *skc, void *ptr, int size)
+{
+ ASSERT(IS_P2ALIGNED(ptr, PAGE_SIZE));
+
+ /*
+ * The Linux direct reclaim path uses this out of band value to
+ * determine if forward progress is being made. Normally this is
+ * incremented by kmem_freepages() which is part of the various
+ * Linux slab implementations. However, since we are using none
+ * of that infrastructure we are responsible for incrementing it.
+ */
+ if (current->reclaim_state)
+ current->reclaim_state->reclaimed_slab += size >> PAGE_SHIFT;
+
+ vfree(ptr);
+}
+
+/*
+ * Required space for each aligned sks.
+ */
+static inline uint32_t
+spl_sks_size(spl_kmem_cache_t *skc)
+{
+ return (P2ROUNDUP_TYPED(sizeof (spl_kmem_slab_t),
+ skc->skc_obj_align, uint32_t));
+}
+
+/*
+ * Required space for each aligned object.
+ */
+static inline uint32_t
+spl_obj_size(spl_kmem_cache_t *skc)
+{
+ uint32_t align = skc->skc_obj_align;
+
+ return (P2ROUNDUP_TYPED(skc->skc_obj_size, align, uint32_t) +
+ P2ROUNDUP_TYPED(sizeof (spl_kmem_obj_t), align, uint32_t));
+}
+
+uint64_t
+spl_kmem_cache_inuse(kmem_cache_t *cache)
+{
+ return (cache->skc_obj_total);
+}
+EXPORT_SYMBOL(spl_kmem_cache_inuse);
+
+uint64_t
+spl_kmem_cache_entry_size(kmem_cache_t *cache)
+{
+ return (cache->skc_obj_size);
+}
+EXPORT_SYMBOL(spl_kmem_cache_entry_size);
+
+/*
+ * Lookup the spl_kmem_object_t for an object given that object.
+ */
+static inline spl_kmem_obj_t *
+spl_sko_from_obj(spl_kmem_cache_t *skc, void *obj)
+{
+ return (obj + P2ROUNDUP_TYPED(skc->skc_obj_size,
+ skc->skc_obj_align, uint32_t));
+}
+
+/*
+ * It's important that we pack the spl_kmem_obj_t structure and the
+ * actual objects in to one large address space to minimize the number
+ * of calls to the allocator. It is far better to do a few large
+ * allocations and then subdivide it ourselves. Now which allocator
+ * we use requires balancing a few trade offs.
+ *
+ * For small objects we use kmem_alloc() because as long as you are
+ * only requesting a small number of pages (ideally just one) its cheap.
+ * However, when you start requesting multiple pages with kmem_alloc()
+ * it gets increasingly expensive since it requires contiguous pages.
+ * For this reason we shift to vmem_alloc() for slabs of large objects
+ * which removes the need for contiguous pages. We do not use
+ * vmem_alloc() in all cases because there is significant locking
+ * overhead in __get_vm_area_node(). This function takes a single
+ * global lock when acquiring an available virtual address range which
+ * serializes all vmem_alloc()'s for all slab caches. Using slightly
+ * different allocation functions for small and large objects should
+ * give us the best of both worlds.
+ *
+ * +------------------------+
+ * | spl_kmem_slab_t --+-+ |
+ * | skc_obj_size <-+ | |
+ * | spl_kmem_obj_t | |
+ * | skc_obj_size <---+ |
+ * | spl_kmem_obj_t | |
+ * | ... v |
+ * +------------------------+
+ */
+static spl_kmem_slab_t *
+spl_slab_alloc(spl_kmem_cache_t *skc, int flags)
+{
+ spl_kmem_slab_t *sks;
+ void *base;
+ uint32_t obj_size;
+
+ base = kv_alloc(skc, skc->skc_slab_size, flags);
+ if (base == NULL)
+ return (NULL);
+
+ sks = (spl_kmem_slab_t *)base;
+ sks->sks_magic = SKS_MAGIC;
+ sks->sks_objs = skc->skc_slab_objs;
+ sks->sks_age = jiffies;
+ sks->sks_cache = skc;
+ INIT_LIST_HEAD(&sks->sks_list);
+ INIT_LIST_HEAD(&sks->sks_free_list);
+ sks->sks_ref = 0;
+ obj_size = spl_obj_size(skc);
+
+ for (int i = 0; i < sks->sks_objs; i++) {
+ void *obj = base + spl_sks_size(skc) + (i * obj_size);
+
+ ASSERT(IS_P2ALIGNED(obj, skc->skc_obj_align));
+ spl_kmem_obj_t *sko = spl_sko_from_obj(skc, obj);
+ sko->sko_addr = obj;
+ sko->sko_magic = SKO_MAGIC;
+ sko->sko_slab = sks;
+ INIT_LIST_HEAD(&sko->sko_list);
+ list_add_tail(&sko->sko_list, &sks->sks_free_list);
+ }
+
+ return (sks);
+}
+
+/*
+ * Remove a slab from complete or partial list, it must be called with
+ * the 'skc->skc_lock' held but the actual free must be performed
+ * outside the lock to prevent deadlocking on vmem addresses.
+ */
+static void
+spl_slab_free(spl_kmem_slab_t *sks,
+ struct list_head *sks_list, struct list_head *sko_list)
+{
+ spl_kmem_cache_t *skc;
+
+ ASSERT(sks->sks_magic == SKS_MAGIC);
+ ASSERT(sks->sks_ref == 0);
+
+ skc = sks->sks_cache;
+ ASSERT(skc->skc_magic == SKC_MAGIC);
+
+ /*
+ * Update slab/objects counters in the cache, then remove the
+ * slab from the skc->skc_partial_list. Finally add the slab
+ * and all its objects in to the private work lists where the
+ * destructors will be called and the memory freed to the system.
+ */
+ skc->skc_obj_total -= sks->sks_objs;
+ skc->skc_slab_total--;
+ list_del(&sks->sks_list);
+ list_add(&sks->sks_list, sks_list);
+ list_splice_init(&sks->sks_free_list, sko_list);
+}
+
+/*
+ * Reclaim empty slabs at the end of the partial list.
+ */
+static void
+spl_slab_reclaim(spl_kmem_cache_t *skc)
+{
+ spl_kmem_slab_t *sks = NULL, *m = NULL;
+ spl_kmem_obj_t *sko = NULL, *n = NULL;
+ LIST_HEAD(sks_list);
+ LIST_HEAD(sko_list);
+
+ /*
+ * Empty slabs and objects must be moved to a private list so they
+ * can be safely freed outside the spin lock. All empty slabs are
+ * at the end of skc->skc_partial_list, therefore once a non-empty
+ * slab is found we can stop scanning.
+ */
+ spin_lock(&skc->skc_lock);
+ list_for_each_entry_safe_reverse(sks, m,
+ &skc->skc_partial_list, sks_list) {
+
+ if (sks->sks_ref > 0)
+ break;
+
+ spl_slab_free(sks, &sks_list, &sko_list);
+ }
+ spin_unlock(&skc->skc_lock);
+
+ /*
+ * The following two loops ensure all the object destructors are run,
+ * and the slabs themselves are freed. This is all done outside the
+ * skc->skc_lock since this allows the destructor to sleep, and
+ * allows us to perform a conditional reschedule when a freeing a
+ * large number of objects and slabs back to the system.
+ */
+
+ list_for_each_entry_safe(sko, n, &sko_list, sko_list) {
+ ASSERT(sko->sko_magic == SKO_MAGIC);
+ }
+
+ list_for_each_entry_safe(sks, m, &sks_list, sks_list) {
+ ASSERT(sks->sks_magic == SKS_MAGIC);
+ kv_free(skc, sks, skc->skc_slab_size);
+ }
+}
+
+static spl_kmem_emergency_t *
+spl_emergency_search(struct rb_root *root, void *obj)
+{
+ struct rb_node *node = root->rb_node;
+ spl_kmem_emergency_t *ske;
+ unsigned long address = (unsigned long)obj;
+
+ while (node) {
+ ske = container_of(node, spl_kmem_emergency_t, ske_node);
+
+ if (address < ske->ske_obj)
+ node = node->rb_left;
+ else if (address > ske->ske_obj)
+ node = node->rb_right;
+ else
+ return (ske);
+ }
+
+ return (NULL);
+}
+
+static int
+spl_emergency_insert(struct rb_root *root, spl_kmem_emergency_t *ske)
+{
+ struct rb_node **new = &(root->rb_node), *parent = NULL;
+ spl_kmem_emergency_t *ske_tmp;
+ unsigned long address = ske->ske_obj;
+
+ while (*new) {
+ ske_tmp = container_of(*new, spl_kmem_emergency_t, ske_node);
+
+ parent = *new;
+ if (address < ske_tmp->ske_obj)
+ new = &((*new)->rb_left);
+ else if (address > ske_tmp->ske_obj)
+ new = &((*new)->rb_right);
+ else
+ return (0);
+ }
+
+ rb_link_node(&ske->ske_node, parent, new);
+ rb_insert_color(&ske->ske_node, root);
+
+ return (1);
+}
+
+/*
+ * Allocate a single emergency object and track it in a red black tree.
+ */
+static int
+spl_emergency_alloc(spl_kmem_cache_t *skc, int flags, void **obj)
+{
+ gfp_t lflags = kmem_flags_convert(flags);
+ spl_kmem_emergency_t *ske;
+ int order = get_order(skc->skc_obj_size);
+ int empty;
+
+ /* Last chance use a partial slab if one now exists */
+ spin_lock(&skc->skc_lock);
+ empty = list_empty(&skc->skc_partial_list);
+ spin_unlock(&skc->skc_lock);
+ if (!empty)
+ return (-EEXIST);
+
+ ske = kmalloc(sizeof (*ske), lflags);
+ if (ske == NULL)
+ return (-ENOMEM);
+
+ ske->ske_obj = __get_free_pages(lflags, order);
+ if (ske->ske_obj == 0) {
+ kfree(ske);
+ return (-ENOMEM);
+ }
+
+ spin_lock(&skc->skc_lock);
+ empty = spl_emergency_insert(&skc->skc_emergency_tree, ske);
+ if (likely(empty)) {
+ skc->skc_obj_total++;
+ skc->skc_obj_emergency++;
+ if (skc->skc_obj_emergency > skc->skc_obj_emergency_max)
+ skc->skc_obj_emergency_max = skc->skc_obj_emergency;
+ }
+ spin_unlock(&skc->skc_lock);
+
+ if (unlikely(!empty)) {
+ free_pages(ske->ske_obj, order);
+ kfree(ske);
+ return (-EINVAL);
+ }
+
+ *obj = (void *)ske->ske_obj;
+
+ return (0);
+}
+
+/*
+ * Locate the passed object in the red black tree and free it.
+ */
+static int
+spl_emergency_free(spl_kmem_cache_t *skc, void *obj)
+{
+ spl_kmem_emergency_t *ske;
+ int order = get_order(skc->skc_obj_size);
+
+ spin_lock(&skc->skc_lock);
+ ske = spl_emergency_search(&skc->skc_emergency_tree, obj);
+ if (ske) {
+ rb_erase(&ske->ske_node, &skc->skc_emergency_tree);
+ skc->skc_obj_emergency--;
+ skc->skc_obj_total--;
+ }
+ spin_unlock(&skc->skc_lock);
+
+ if (ske == NULL)
+ return (-ENOENT);
+
+ free_pages(ske->ske_obj, order);
+ kfree(ske);
+
+ return (0);
+}
+
+/*
+ * Release objects from the per-cpu magazine back to their slab. The flush
+ * argument contains the max number of entries to remove from the magazine.
+ */
+static void
+spl_cache_flush(spl_kmem_cache_t *skc, spl_kmem_magazine_t *skm, int flush)
+{
+ spin_lock(&skc->skc_lock);
+
+ ASSERT(skc->skc_magic == SKC_MAGIC);
+ ASSERT(skm->skm_magic == SKM_MAGIC);
+
+ int count = MIN(flush, skm->skm_avail);
+ for (int i = 0; i < count; i++)
+ spl_cache_shrink(skc, skm->skm_objs[i]);
+
+ skm->skm_avail -= count;
+ memmove(skm->skm_objs, &(skm->skm_objs[count]),
+ sizeof (void *) * skm->skm_avail);
+
+ spin_unlock(&skc->skc_lock);
+}
+
+/*
+ * Size a slab based on the size of each aligned object plus spl_kmem_obj_t.
+ * When on-slab we want to target spl_kmem_cache_obj_per_slab. However,
+ * for very small objects we may end up with more than this so as not
+ * to waste space in the minimal allocation of a single page. Also for
+ * very large objects we may use as few as spl_kmem_cache_obj_per_slab_min,
+ * lower than this and we will fail.
+ */
+static int
+spl_slab_size(spl_kmem_cache_t *skc, uint32_t *objs, uint32_t *size)
+{
+ uint32_t sks_size, obj_size, max_size, tgt_size, tgt_objs;
+
+ sks_size = spl_sks_size(skc);
+ obj_size = spl_obj_size(skc);
+ max_size = (spl_kmem_cache_max_size * 1024 * 1024);
+ tgt_size = (spl_kmem_cache_obj_per_slab * obj_size + sks_size);
+
+ if (tgt_size <= max_size) {
+ tgt_objs = (tgt_size - sks_size) / obj_size;
+ } else {
+ tgt_objs = (max_size - sks_size) / obj_size;
+ tgt_size = (tgt_objs * obj_size) + sks_size;
+ }
+
+ if (tgt_objs == 0)
+ return (-ENOSPC);
+
+ *objs = tgt_objs;
+ *size = tgt_size;
+
+ return (0);
+}
+
+/*
+ * Make a guess at reasonable per-cpu magazine size based on the size of
+ * each object and the cost of caching N of them in each magazine. Long
+ * term this should really adapt based on an observed usage heuristic.
+ */
+static int
+spl_magazine_size(spl_kmem_cache_t *skc)
+{
+ uint32_t obj_size = spl_obj_size(skc);
+ int size;
+
+ if (spl_kmem_cache_magazine_size > 0)
+ return (MAX(MIN(spl_kmem_cache_magazine_size, 256), 2));
+
+ /* Per-magazine sizes below assume a 4Kib page size */
+ if (obj_size > (PAGE_SIZE * 256))
+ size = 4; /* Minimum 4Mib per-magazine */
+ else if (obj_size > (PAGE_SIZE * 32))
+ size = 16; /* Minimum 2Mib per-magazine */
+ else if (obj_size > (PAGE_SIZE))
+ size = 64; /* Minimum 256Kib per-magazine */
+ else if (obj_size > (PAGE_SIZE / 4))
+ size = 128; /* Minimum 128Kib per-magazine */
+ else
+ size = 256;
+
+ return (size);
+}
+
+/*
+ * Allocate a per-cpu magazine to associate with a specific core.
+ */
+static spl_kmem_magazine_t *
+spl_magazine_alloc(spl_kmem_cache_t *skc, int cpu)
+{
+ spl_kmem_magazine_t *skm;
+ int size = sizeof (spl_kmem_magazine_t) +
+ sizeof (void *) * skc->skc_mag_size;
+
+ skm = kmalloc_node(size, GFP_KERNEL, cpu_to_node(cpu));
+ if (skm) {
+ skm->skm_magic = SKM_MAGIC;
+ skm->skm_avail = 0;
+ skm->skm_size = skc->skc_mag_size;
+ skm->skm_refill = skc->skc_mag_refill;
+ skm->skm_cache = skc;
+ skm->skm_cpu = cpu;
+ }
+
+ return (skm);
+}
+
+/*
+ * Free a per-cpu magazine associated with a specific core.
+ */
+static void
+spl_magazine_free(spl_kmem_magazine_t *skm)
+{
+ ASSERT(skm->skm_magic == SKM_MAGIC);
+ ASSERT(skm->skm_avail == 0);
+ kfree(skm);
+}
+
+/*
+ * Create all pre-cpu magazines of reasonable sizes.
+ */
+static int
+spl_magazine_create(spl_kmem_cache_t *skc)
+{
+ int i = 0;
+
+ ASSERT((skc->skc_flags & KMC_SLAB) == 0);
+
+ skc->skc_mag = kzalloc(sizeof (spl_kmem_magazine_t *) *
+ num_possible_cpus(), kmem_flags_convert(KM_SLEEP));
+ skc->skc_mag_size = spl_magazine_size(skc);
+ skc->skc_mag_refill = (skc->skc_mag_size + 1) / 2;
+
+ for_each_possible_cpu(i) {
+ skc->skc_mag[i] = spl_magazine_alloc(skc, i);
+ if (!skc->skc_mag[i]) {
+ for (i--; i >= 0; i--)
+ spl_magazine_free(skc->skc_mag[i]);
+
+ kfree(skc->skc_mag);
+ return (-ENOMEM);
+ }
+ }
+
+ return (0);
+}
+
+/*
+ * Destroy all pre-cpu magazines.
+ */
+static void
+spl_magazine_destroy(spl_kmem_cache_t *skc)
+{
+ spl_kmem_magazine_t *skm;
+ int i = 0;
+
+ ASSERT((skc->skc_flags & KMC_SLAB) == 0);
+
+ for_each_possible_cpu(i) {
+ skm = skc->skc_mag[i];
+ spl_cache_flush(skc, skm, skm->skm_avail);
+ spl_magazine_free(skm);
+ }
+
+ kfree(skc->skc_mag);
+}
+
+/*
+ * Create a object cache based on the following arguments:
+ * name cache name
+ * size cache object size
+ * align cache object alignment
+ * ctor cache object constructor
+ * dtor cache object destructor
+ * reclaim cache object reclaim
+ * priv cache private data for ctor/dtor/reclaim
+ * vmp unused must be NULL
+ * flags
+ * KMC_KVMEM Force kvmem backed SPL cache
+ * KMC_SLAB Force Linux slab backed cache
+ * KMC_NODEBUG Disable debugging (unsupported)
+ */
+spl_kmem_cache_t *
+spl_kmem_cache_create(char *name, size_t size, size_t align,
+ spl_kmem_ctor_t ctor, spl_kmem_dtor_t dtor, void *reclaim,
+ void *priv, void *vmp, int flags)
+{
+ gfp_t lflags = kmem_flags_convert(KM_SLEEP);
+ spl_kmem_cache_t *skc;
+ int rc;
+
+ /*
+ * Unsupported flags
+ */
+ ASSERT(vmp == NULL);
+ ASSERT(reclaim == NULL);
+
+ might_sleep();
+
+ skc = kzalloc(sizeof (*skc), lflags);
+ if (skc == NULL)
+ return (NULL);
+
+ skc->skc_magic = SKC_MAGIC;
+ skc->skc_name_size = strlen(name) + 1;
+ skc->skc_name = (char *)kmalloc(skc->skc_name_size, lflags);
+ if (skc->skc_name == NULL) {
+ kfree(skc);
+ return (NULL);
+ }
+ strncpy(skc->skc_name, name, skc->skc_name_size);
+
+ skc->skc_ctor = ctor;
+ skc->skc_dtor = dtor;
+ skc->skc_private = priv;
+ skc->skc_vmp = vmp;
+ skc->skc_linux_cache = NULL;
+ skc->skc_flags = flags;
+ skc->skc_obj_size = size;
+ skc->skc_obj_align = SPL_KMEM_CACHE_ALIGN;
+ atomic_set(&skc->skc_ref, 0);
+
+ INIT_LIST_HEAD(&skc->skc_list);
+ INIT_LIST_HEAD(&skc->skc_complete_list);
+ INIT_LIST_HEAD(&skc->skc_partial_list);
+ skc->skc_emergency_tree = RB_ROOT;
+ spin_lock_init(&skc->skc_lock);
+ init_waitqueue_head(&skc->skc_waitq);
+ skc->skc_slab_fail = 0;
+ skc->skc_slab_create = 0;
+ skc->skc_slab_destroy = 0;
+ skc->skc_slab_total = 0;
+ skc->skc_slab_alloc = 0;
+ skc->skc_slab_max = 0;
+ skc->skc_obj_total = 0;
+ skc->skc_obj_alloc = 0;
+ skc->skc_obj_max = 0;
+ skc->skc_obj_deadlock = 0;
+ skc->skc_obj_emergency = 0;
+ skc->skc_obj_emergency_max = 0;
+
+ rc = percpu_counter_init_common(&skc->skc_linux_alloc, 0,
+ GFP_KERNEL);
+ if (rc != 0) {
+ kfree(skc);
+ return (NULL);
+ }
+
+ /*
+ * Verify the requested alignment restriction is sane.
+ */
+ if (align) {
+ VERIFY(ISP2(align));
+ VERIFY3U(align, >=, SPL_KMEM_CACHE_ALIGN);
+ VERIFY3U(align, <=, PAGE_SIZE);
+ skc->skc_obj_align = align;
+ }
+
+ /*
+ * When no specific type of slab is requested (kmem, vmem, or
+ * linuxslab) then select a cache type based on the object size
+ * and default tunables.
+ */
+ if (!(skc->skc_flags & (KMC_SLAB | KMC_KVMEM))) {
+ if (spl_kmem_cache_slab_limit &&
+ size <= (size_t)spl_kmem_cache_slab_limit) {
+ /*
+ * Objects smaller than spl_kmem_cache_slab_limit can
+ * use the Linux slab for better space-efficiency.
+ */
+ skc->skc_flags |= KMC_SLAB;
+ } else {
+ /*
+ * All other objects are considered large and are
+ * placed on kvmem backed slabs.
+ */
+ skc->skc_flags |= KMC_KVMEM;
+ }
+ }
+
+ /*
+ * Given the type of slab allocate the required resources.
+ */
+ if (skc->skc_flags & KMC_KVMEM) {
+ rc = spl_slab_size(skc,
+ &skc->skc_slab_objs, &skc->skc_slab_size);
+ if (rc)
+ goto out;
+
+ rc = spl_magazine_create(skc);
+ if (rc)
+ goto out;
+ } else {
+ unsigned long slabflags = 0;
+
+ if (size > (SPL_MAX_KMEM_ORDER_NR_PAGES * PAGE_SIZE)) {
+ rc = EINVAL;
+ goto out;
+ }
+
+#if defined(SLAB_USERCOPY)
+ /*
+ * Required for PAX-enabled kernels if the slab is to be
+ * used for copying between user and kernel space.
+ */
+ slabflags |= SLAB_USERCOPY;
+#endif
+
+#if defined(HAVE_KMEM_CACHE_CREATE_USERCOPY)
+ /*
+ * Newer grsec patchset uses kmem_cache_create_usercopy()
+ * instead of SLAB_USERCOPY flag
+ */
+ skc->skc_linux_cache = kmem_cache_create_usercopy(
+ skc->skc_name, size, align, slabflags, 0, size, NULL);
+#else
+ skc->skc_linux_cache = kmem_cache_create(
+ skc->skc_name, size, align, slabflags, NULL);
+#endif
+ if (skc->skc_linux_cache == NULL) {
+ rc = ENOMEM;
+ goto out;
+ }
+ }
+
+ down_write(&spl_kmem_cache_sem);
+ list_add_tail(&skc->skc_list, &spl_kmem_cache_list);
+ up_write(&spl_kmem_cache_sem);
+
+ return (skc);
+out:
+ kfree(skc->skc_name);
+ percpu_counter_destroy(&skc->skc_linux_alloc);
+ kfree(skc);
+ return (NULL);
+}
+EXPORT_SYMBOL(spl_kmem_cache_create);
+
+/*
+ * Register a move callback for cache defragmentation.
+ * XXX: Unimplemented but harmless to stub out for now.
+ */
+void
+spl_kmem_cache_set_move(spl_kmem_cache_t *skc,
+ kmem_cbrc_t (move)(void *, void *, size_t, void *))
+{
+ ASSERT(move != NULL);
+}
+EXPORT_SYMBOL(spl_kmem_cache_set_move);
+
+/*
+ * Destroy a cache and all objects associated with the cache.
+ */
+void
+spl_kmem_cache_destroy(spl_kmem_cache_t *skc)
+{
+ DECLARE_WAIT_QUEUE_HEAD(wq);
+ taskqid_t id;
+
+ ASSERT(skc->skc_magic == SKC_MAGIC);
+ ASSERT(skc->skc_flags & (KMC_KVMEM | KMC_SLAB));
+
+ down_write(&spl_kmem_cache_sem);
+ list_del_init(&skc->skc_list);
+ up_write(&spl_kmem_cache_sem);
+
+ /* Cancel any and wait for any pending delayed tasks */
+ VERIFY(!test_and_set_bit(KMC_BIT_DESTROY, &skc->skc_flags));
+
+ spin_lock(&skc->skc_lock);
+ id = skc->skc_taskqid;
+ spin_unlock(&skc->skc_lock);
+
+ taskq_cancel_id(spl_kmem_cache_taskq, id);
+
+ /*
+ * Wait until all current callers complete, this is mainly
+ * to catch the case where a low memory situation triggers a
+ * cache reaping action which races with this destroy.
+ */
+ wait_event(wq, atomic_read(&skc->skc_ref) == 0);
+
+ if (skc->skc_flags & KMC_KVMEM) {
+ spl_magazine_destroy(skc);
+ spl_slab_reclaim(skc);
+ } else {
+ ASSERT(skc->skc_flags & KMC_SLAB);
+ kmem_cache_destroy(skc->skc_linux_cache);
+ }
+
+ spin_lock(&skc->skc_lock);
+
+ /*
+ * Validate there are no objects in use and free all the
+ * spl_kmem_slab_t, spl_kmem_obj_t, and object buffers.
+ */
+ ASSERT3U(skc->skc_slab_alloc, ==, 0);
+ ASSERT3U(skc->skc_obj_alloc, ==, 0);
+ ASSERT3U(skc->skc_slab_total, ==, 0);
+ ASSERT3U(skc->skc_obj_total, ==, 0);
+ ASSERT3U(skc->skc_obj_emergency, ==, 0);
+ ASSERT(list_empty(&skc->skc_complete_list));
+
+ ASSERT3U(percpu_counter_sum(&skc->skc_linux_alloc), ==, 0);
+ percpu_counter_destroy(&skc->skc_linux_alloc);
+
+ spin_unlock(&skc->skc_lock);
+
+ kfree(skc->skc_name);
+ kfree(skc);
+}
+EXPORT_SYMBOL(spl_kmem_cache_destroy);
+
+/*
+ * Allocate an object from a slab attached to the cache. This is used to
+ * repopulate the per-cpu magazine caches in batches when they run low.
+ */
+static void *
+spl_cache_obj(spl_kmem_cache_t *skc, spl_kmem_slab_t *sks)
+{
+ spl_kmem_obj_t *sko;
+
+ ASSERT(skc->skc_magic == SKC_MAGIC);
+ ASSERT(sks->sks_magic == SKS_MAGIC);
+
+ sko = list_entry(sks->sks_free_list.next, spl_kmem_obj_t, sko_list);
+ ASSERT(sko->sko_magic == SKO_MAGIC);
+ ASSERT(sko->sko_addr != NULL);
+
+ /* Remove from sks_free_list */
+ list_del_init(&sko->sko_list);
+
+ sks->sks_age = jiffies;
+ sks->sks_ref++;
+ skc->skc_obj_alloc++;
+
+ /* Track max obj usage statistics */
+ if (skc->skc_obj_alloc > skc->skc_obj_max)
+ skc->skc_obj_max = skc->skc_obj_alloc;
+
+ /* Track max slab usage statistics */
+ if (sks->sks_ref == 1) {
+ skc->skc_slab_alloc++;
+
+ if (skc->skc_slab_alloc > skc->skc_slab_max)
+ skc->skc_slab_max = skc->skc_slab_alloc;
+ }
+
+ return (sko->sko_addr);
+}
+
+/*
+ * Generic slab allocation function to run by the global work queues.
+ * It is responsible for allocating a new slab, linking it in to the list
+ * of partial slabs, and then waking any waiters.
+ */
+static int
+__spl_cache_grow(spl_kmem_cache_t *skc, int flags)
+{
+ spl_kmem_slab_t *sks;
+
+ fstrans_cookie_t cookie = spl_fstrans_mark();
+ sks = spl_slab_alloc(skc, flags);
+ spl_fstrans_unmark(cookie);
+
+ spin_lock(&skc->skc_lock);
+ if (sks) {
+ skc->skc_slab_total++;
+ skc->skc_obj_total += sks->sks_objs;
+ list_add_tail(&sks->sks_list, &skc->skc_partial_list);
+
+ smp_mb__before_atomic();
+ clear_bit(KMC_BIT_DEADLOCKED, &skc->skc_flags);
+ smp_mb__after_atomic();
+ }
+ spin_unlock(&skc->skc_lock);
+
+ return (sks == NULL ? -ENOMEM : 0);
+}
+
+static void
+spl_cache_grow_work(void *data)
+{
+ spl_kmem_alloc_t *ska = (spl_kmem_alloc_t *)data;
+ spl_kmem_cache_t *skc = ska->ska_cache;
+
+ int error = __spl_cache_grow(skc, ska->ska_flags);
+
+ atomic_dec(&skc->skc_ref);
+ smp_mb__before_atomic();
+ clear_bit(KMC_BIT_GROWING, &skc->skc_flags);
+ smp_mb__after_atomic();
+ if (error == 0)
+ wake_up_all(&skc->skc_waitq);
+
+ kfree(ska);
+}
+
+/*
+ * Returns non-zero when a new slab should be available.
+ */
+static int
+spl_cache_grow_wait(spl_kmem_cache_t *skc)
+{
+ return (!test_bit(KMC_BIT_GROWING, &skc->skc_flags));
+}
+
+/*
+ * No available objects on any slabs, create a new slab. Note that this
+ * functionality is disabled for KMC_SLAB caches which are backed by the
+ * Linux slab.
+ */
+static int
+spl_cache_grow(spl_kmem_cache_t *skc, int flags, void **obj)
+{
+ int remaining, rc = 0;
+
+ ASSERT0(flags & ~KM_PUBLIC_MASK);
+ ASSERT(skc->skc_magic == SKC_MAGIC);
+ ASSERT((skc->skc_flags & KMC_SLAB) == 0);
+ might_sleep();
+ *obj = NULL;
+
+ /*
+ * Before allocating a new slab wait for any reaping to complete and
+ * then return so the local magazine can be rechecked for new objects.
+ */
+ if (test_bit(KMC_BIT_REAPING, &skc->skc_flags)) {
+ rc = spl_wait_on_bit(&skc->skc_flags, KMC_BIT_REAPING,
+ TASK_UNINTERRUPTIBLE);
+ return (rc ? rc : -EAGAIN);
+ }
+
+ /*
+ * Note: It would be nice to reduce the overhead of context switch
+ * and improve NUMA locality, by trying to allocate a new slab in the
+ * current process context with KM_NOSLEEP flag.
+ *
+ * However, this can't be applied to vmem/kvmem due to a bug that
+ * spl_vmalloc() doesn't honor gfp flags in page table allocation.
+ */
+
+ /*
+ * This is handled by dispatching a work request to the global work
+ * queue. This allows us to asynchronously allocate a new slab while
+ * retaining the ability to safely fall back to a smaller synchronous
+ * allocations to ensure forward progress is always maintained.
+ */
+ if (test_and_set_bit(KMC_BIT_GROWING, &skc->skc_flags) == 0) {
+ spl_kmem_alloc_t *ska;
+
+ ska = kmalloc(sizeof (*ska), kmem_flags_convert(flags));
+ if (ska == NULL) {
+ clear_bit_unlock(KMC_BIT_GROWING, &skc->skc_flags);
+ smp_mb__after_atomic();
+ wake_up_all(&skc->skc_waitq);
+ return (-ENOMEM);
+ }
+
+ atomic_inc(&skc->skc_ref);
+ ska->ska_cache = skc;
+ ska->ska_flags = flags;
+ taskq_init_ent(&ska->ska_tqe);
+ taskq_dispatch_ent(spl_kmem_cache_taskq,
+ spl_cache_grow_work, ska, 0, &ska->ska_tqe);
+ }
+
+ /*
+ * The goal here is to only detect the rare case where a virtual slab
+ * allocation has deadlocked. We must be careful to minimize the use
+ * of emergency objects which are more expensive to track. Therefore,
+ * we set a very long timeout for the asynchronous allocation and if
+ * the timeout is reached the cache is flagged as deadlocked. From
+ * this point only new emergency objects will be allocated until the
+ * asynchronous allocation completes and clears the deadlocked flag.
+ */
+ if (test_bit(KMC_BIT_DEADLOCKED, &skc->skc_flags)) {
+ rc = spl_emergency_alloc(skc, flags, obj);
+ } else {
+ remaining = wait_event_timeout(skc->skc_waitq,
+ spl_cache_grow_wait(skc), HZ / 10);
+
+ if (!remaining) {
+ spin_lock(&skc->skc_lock);
+ if (test_bit(KMC_BIT_GROWING, &skc->skc_flags)) {
+ set_bit(KMC_BIT_DEADLOCKED, &skc->skc_flags);
+ skc->skc_obj_deadlock++;
+ }
+ spin_unlock(&skc->skc_lock);
+ }
+
+ rc = -ENOMEM;
+ }
+
+ return (rc);
+}
+
+/*
+ * Refill a per-cpu magazine with objects from the slabs for this cache.
+ * Ideally the magazine can be repopulated using existing objects which have
+ * been released, however if we are unable to locate enough free objects new
+ * slabs of objects will be created. On success NULL is returned, otherwise
+ * the address of a single emergency object is returned for use by the caller.
+ */
+static void *
+spl_cache_refill(spl_kmem_cache_t *skc, spl_kmem_magazine_t *skm, int flags)
+{
+ spl_kmem_slab_t *sks;
+ int count = 0, rc, refill;
+ void *obj = NULL;
+
+ ASSERT(skc->skc_magic == SKC_MAGIC);
+ ASSERT(skm->skm_magic == SKM_MAGIC);
+
+ refill = MIN(skm->skm_refill, skm->skm_size - skm->skm_avail);
+ spin_lock(&skc->skc_lock);
+
+ while (refill > 0) {
+ /* No slabs available we may need to grow the cache */
+ if (list_empty(&skc->skc_partial_list)) {
+ spin_unlock(&skc->skc_lock);
+
+ local_irq_enable();
+ rc = spl_cache_grow(skc, flags, &obj);
+ local_irq_disable();
+
+ /* Emergency object for immediate use by caller */
+ if (rc == 0 && obj != NULL)
+ return (obj);
+
+ if (rc)
+ goto out;
+
+ /* Rescheduled to different CPU skm is not local */
+ if (skm != skc->skc_mag[smp_processor_id()])
+ goto out;
+
+ /*
+ * Potentially rescheduled to the same CPU but
+ * allocations may have occurred from this CPU while
+ * we were sleeping so recalculate max refill.
+ */
+ refill = MIN(refill, skm->skm_size - skm->skm_avail);
+
+ spin_lock(&skc->skc_lock);
+ continue;
+ }
+
+ /* Grab the next available slab */
+ sks = list_entry((&skc->skc_partial_list)->next,
+ spl_kmem_slab_t, sks_list);
+ ASSERT(sks->sks_magic == SKS_MAGIC);
+ ASSERT(sks->sks_ref < sks->sks_objs);
+ ASSERT(!list_empty(&sks->sks_free_list));
+
+ /*
+ * Consume as many objects as needed to refill the requested
+ * cache. We must also be careful not to overfill it.
+ */
+ while (sks->sks_ref < sks->sks_objs && refill-- > 0 &&
+ ++count) {
+ ASSERT(skm->skm_avail < skm->skm_size);
+ ASSERT(count < skm->skm_size);
+ skm->skm_objs[skm->skm_avail++] =
+ spl_cache_obj(skc, sks);
+ }
+
+ /* Move slab to skc_complete_list when full */
+ if (sks->sks_ref == sks->sks_objs) {
+ list_del(&sks->sks_list);
+ list_add(&sks->sks_list, &skc->skc_complete_list);
+ }
+ }
+
+ spin_unlock(&skc->skc_lock);
+out:
+ return (NULL);
+}
+
+/*
+ * Release an object back to the slab from which it came.
+ */
+static void
+spl_cache_shrink(spl_kmem_cache_t *skc, void *obj)
+{
+ spl_kmem_slab_t *sks = NULL;
+ spl_kmem_obj_t *sko = NULL;
+
+ ASSERT(skc->skc_magic == SKC_MAGIC);
+
+ sko = spl_sko_from_obj(skc, obj);
+ ASSERT(sko->sko_magic == SKO_MAGIC);
+ sks = sko->sko_slab;
+ ASSERT(sks->sks_magic == SKS_MAGIC);
+ ASSERT(sks->sks_cache == skc);
+ list_add(&sko->sko_list, &sks->sks_free_list);
+
+ sks->sks_age = jiffies;
+ sks->sks_ref--;
+ skc->skc_obj_alloc--;
+
+ /*
+ * Move slab to skc_partial_list when no longer full. Slabs
+ * are added to the head to keep the partial list is quasi-full
+ * sorted order. Fuller at the head, emptier at the tail.
+ */
+ if (sks->sks_ref == (sks->sks_objs - 1)) {
+ list_del(&sks->sks_list);
+ list_add(&sks->sks_list, &skc->skc_partial_list);
+ }
+
+ /*
+ * Move empty slabs to the end of the partial list so
+ * they can be easily found and freed during reclamation.
+ */
+ if (sks->sks_ref == 0) {
+ list_del(&sks->sks_list);
+ list_add_tail(&sks->sks_list, &skc->skc_partial_list);
+ skc->skc_slab_alloc--;
+ }
+}
+
+/*
+ * Allocate an object from the per-cpu magazine, or if the magazine
+ * is empty directly allocate from a slab and repopulate the magazine.
+ */
+void *
+spl_kmem_cache_alloc(spl_kmem_cache_t *skc, int flags)
+{
+ spl_kmem_magazine_t *skm;
+ void *obj = NULL;
+
+ ASSERT0(flags & ~KM_PUBLIC_MASK);
+ ASSERT(skc->skc_magic == SKC_MAGIC);
+ ASSERT(!test_bit(KMC_BIT_DESTROY, &skc->skc_flags));
+
+ /*
+ * Allocate directly from a Linux slab. All optimizations are left
+ * to the underlying cache we only need to guarantee that KM_SLEEP
+ * callers will never fail.
+ */
+ if (skc->skc_flags & KMC_SLAB) {
+ struct kmem_cache *slc = skc->skc_linux_cache;
+ do {
+ obj = kmem_cache_alloc(slc, kmem_flags_convert(flags));
+ } while ((obj == NULL) && !(flags & KM_NOSLEEP));
+
+ if (obj != NULL) {
+ /*
+ * Even though we leave everything up to the
+ * underlying cache we still keep track of
+ * how many objects we've allocated in it for
+ * better debuggability.
+ */
+ percpu_counter_inc(&skc->skc_linux_alloc);
+ }
+ goto ret;
+ }
+
+ local_irq_disable();
+
+restart:
+ /*
+ * Safe to update per-cpu structure without lock, but
+ * in the restart case we must be careful to reacquire
+ * the local magazine since this may have changed
+ * when we need to grow the cache.
+ */
+ skm = skc->skc_mag[smp_processor_id()];
+ ASSERT(skm->skm_magic == SKM_MAGIC);
+
+ if (likely(skm->skm_avail)) {
+ /* Object available in CPU cache, use it */
+ obj = skm->skm_objs[--skm->skm_avail];
+ } else {
+ obj = spl_cache_refill(skc, skm, flags);
+ if ((obj == NULL) && !(flags & KM_NOSLEEP))
+ goto restart;
+
+ local_irq_enable();
+ goto ret;
+ }
+
+ local_irq_enable();
+ ASSERT(obj);
+ ASSERT(IS_P2ALIGNED(obj, skc->skc_obj_align));
+
+ret:
+ /* Pre-emptively migrate object to CPU L1 cache */
+ if (obj) {
+ if (obj && skc->skc_ctor)
+ skc->skc_ctor(obj, skc->skc_private, flags);
+ else
+ prefetchw(obj);
+ }
+
+ return (obj);
+}
+EXPORT_SYMBOL(spl_kmem_cache_alloc);
+
+/*
+ * Free an object back to the local per-cpu magazine, there is no
+ * guarantee that this is the same magazine the object was originally
+ * allocated from. We may need to flush entire from the magazine
+ * back to the slabs to make space.
+ */
+void
+spl_kmem_cache_free(spl_kmem_cache_t *skc, void *obj)
+{
+ spl_kmem_magazine_t *skm;
+ unsigned long flags;
+ int do_reclaim = 0;
+ int do_emergency = 0;
+
+ ASSERT(skc->skc_magic == SKC_MAGIC);
+ ASSERT(!test_bit(KMC_BIT_DESTROY, &skc->skc_flags));
+
+ /*
+ * Run the destructor
+ */
+ if (skc->skc_dtor)
+ skc->skc_dtor(obj, skc->skc_private);
+
+ /*
+ * Free the object from the Linux underlying Linux slab.
+ */
+ if (skc->skc_flags & KMC_SLAB) {
+ kmem_cache_free(skc->skc_linux_cache, obj);
+ percpu_counter_dec(&skc->skc_linux_alloc);
+ return;
+ }
+
+ /*
+ * While a cache has outstanding emergency objects all freed objects
+ * must be checked. However, since emergency objects will never use
+ * a virtual address these objects can be safely excluded as an
+ * optimization.
+ */
+ if (!is_vmalloc_addr(obj)) {
+ spin_lock(&skc->skc_lock);
+ do_emergency = (skc->skc_obj_emergency > 0);
+ spin_unlock(&skc->skc_lock);
+
+ if (do_emergency && (spl_emergency_free(skc, obj) == 0))
+ return;
+ }
+
+ local_irq_save(flags);
+
+ /*
+ * Safe to update per-cpu structure without lock, but
+ * no remote memory allocation tracking is being performed
+ * it is entirely possible to allocate an object from one
+ * CPU cache and return it to another.
+ */
+ skm = skc->skc_mag[smp_processor_id()];
+ ASSERT(skm->skm_magic == SKM_MAGIC);
+
+ /*
+ * Per-CPU cache full, flush it to make space for this object,
+ * this may result in an empty slab which can be reclaimed once
+ * interrupts are re-enabled.
+ */
+ if (unlikely(skm->skm_avail >= skm->skm_size)) {
+ spl_cache_flush(skc, skm, skm->skm_refill);
+ do_reclaim = 1;
+ }
+
+ /* Available space in cache, use it */
+ skm->skm_objs[skm->skm_avail++] = obj;
+
+ local_irq_restore(flags);
+
+ if (do_reclaim)
+ spl_slab_reclaim(skc);
+}
+EXPORT_SYMBOL(spl_kmem_cache_free);
+
+/*
+ * Depending on how many and which objects are released it may simply
+ * repopulate the local magazine which will then need to age-out. Objects
+ * which cannot fit in the magazine will be released back to their slabs
+ * which will also need to age out before being released. This is all just
+ * best effort and we do not want to thrash creating and destroying slabs.
+ */
+void
+spl_kmem_cache_reap_now(spl_kmem_cache_t *skc)
+{
+ ASSERT(skc->skc_magic == SKC_MAGIC);
+ ASSERT(!test_bit(KMC_BIT_DESTROY, &skc->skc_flags));
+
+ if (skc->skc_flags & KMC_SLAB)
+ return;
+
+ atomic_inc(&skc->skc_ref);
+
+ /*
+ * Prevent concurrent cache reaping when contended.
+ */
+ if (test_and_set_bit(KMC_BIT_REAPING, &skc->skc_flags))
+ goto out;
+
+ /* Reclaim from the magazine and free all now empty slabs. */
+ unsigned long irq_flags;
+ local_irq_save(irq_flags);
+ spl_kmem_magazine_t *skm = skc->skc_mag[smp_processor_id()];
+ spl_cache_flush(skc, skm, skm->skm_avail);
+ local_irq_restore(irq_flags);
+
+ spl_slab_reclaim(skc);
+ clear_bit_unlock(KMC_BIT_REAPING, &skc->skc_flags);
+ smp_mb__after_atomic();
+ wake_up_bit(&skc->skc_flags, KMC_BIT_REAPING);
+out:
+ atomic_dec(&skc->skc_ref);
+}
+EXPORT_SYMBOL(spl_kmem_cache_reap_now);
+
+/*
+ * This is stubbed out for code consistency with other platforms. There
+ * is existing logic to prevent concurrent reaping so while this is ugly
+ * it should do no harm.
+ */
+int
+spl_kmem_cache_reap_active()
+{
+ return (0);
+}
+EXPORT_SYMBOL(spl_kmem_cache_reap_active);
+
+/*
+ * Reap all free slabs from all registered caches.
+ */
+void
+spl_kmem_reap(void)
+{
+ spl_kmem_cache_t *skc = NULL;
+
+ down_read(&spl_kmem_cache_sem);
+ list_for_each_entry(skc, &spl_kmem_cache_list, skc_list) {
+ spl_kmem_cache_reap_now(skc);
+ }
+ up_read(&spl_kmem_cache_sem);
+}
+EXPORT_SYMBOL(spl_kmem_reap);
+
+int
+spl_kmem_cache_init(void)
+{
+ init_rwsem(&spl_kmem_cache_sem);
+ INIT_LIST_HEAD(&spl_kmem_cache_list);
+ spl_kmem_cache_taskq = taskq_create("spl_kmem_cache",
+ spl_kmem_cache_kmem_threads, maxclsyspri,
+ spl_kmem_cache_kmem_threads * 8, INT_MAX,
+ TASKQ_PREPOPULATE | TASKQ_DYNAMIC);
+
+ return (0);
+}
+
+void
+spl_kmem_cache_fini(void)
+{
+ taskq_destroy(spl_kmem_cache_taskq);
+}