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Commit 18004c5d authored by Christoph Lameter's avatar Christoph Lameter Committed by Pekka Enberg
Browse files

mm, sl[aou]b: Use a common mutex definition 



Use the mutex definition from SLAB and make it the common way to take a sleeping lock.

This has the effect of using a mutex instead of a rw semaphore for SLUB.

SLOB gains the use of a mutex for kmem_cache_create serialization.
Not needed now but SLOB may acquire some more features later (like slabinfo
/ sysfs support) through the expansion of the common code that will
need this.

Reviewed-by: default avatarGlauber Costa <glommer@parallels.com>
Reviewed-by: default avatarJoonsoo Kim <js1304@gmail.com>
Signed-off-by: default avatarChristoph Lameter <cl@linux.com>
Signed-off-by: default avatarPekka Enberg <penberg@kernel.org>
parent 97d06609

mm/slab.c

+51 −57
Original line number Diff line number Diff line
@@ -68,7 +68,7 @@ 
 * Further notes from the original documentation:

 *

 * 11 April '97.  Started multi-threading - markhe

 *	The global cache-chain is protected by the mutex 'cache_chain_mutex'.

 *	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()).
@@ -671,12 +671,6 @@ static void slab_set_debugobj_lock_classes(struct kmem_cache *cachep) 
}

#endif



/*

 * Guard access to the cache-chain.

 */

static DEFINE_MUTEX(cache_chain_mutex);

static struct list_head cache_chain;



static DEFINE_PER_CPU(struct delayed_work, slab_reap_work);



static inline struct array_cache *cpu_cache_get(struct kmem_cache *cachep)
@@ -1100,7 +1094,7 @@ static inline int cache_free_alien(struct kmem_cache *cachep, void *objp) 
 * When hotplugging memory or a cpu, existing nodelists are not replaced if

 * already in use.

 *

 * Must hold cache_chain_mutex.

 * Must hold slab_mutex.

 */

static int init_cache_nodelists_node(int node)

{
@@ -1108,7 +1102,7 @@ static int init_cache_nodelists_node(int node) 
	struct kmem_list3 *l3;

	const int memsize = sizeof(struct kmem_list3);



	list_for_each_entry(cachep, &cache_chain, list) {

	list_for_each_entry(cachep, &slab_caches, list) {

		/*

		 * Set up the size64 kmemlist for cpu before we can

		 * begin anything. Make sure some other cpu on this
@@ -1124,7 +1118,7 @@ static int init_cache_nodelists_node(int node) 


			/*

			 * The l3s don't come and go as CPUs come and

			 * go.  cache_chain_mutex is sufficient

			 * go.  slab_mutex is sufficient

			 * protection here.

			 */

			cachep->nodelists[node] = l3;
@@ -1146,7 +1140,7 @@ static void __cpuinit cpuup_canceled(long cpu) 
	int node = cpu_to_mem(cpu);

	const struct cpumask *mask = cpumask_of_node(node);



	list_for_each_entry(cachep, &cache_chain, list) {

	list_for_each_entry(cachep, &slab_caches, list) {

		struct array_cache *nc;

		struct array_cache *shared;

		struct array_cache **alien;
@@ -1196,7 +1190,7 @@ static void __cpuinit cpuup_canceled(long cpu) 
	 * the respective cache's slabs,  now we can go ahead and

	 * shrink each nodelist to its limit.

	 */

	list_for_each_entry(cachep, &cache_chain, list) {

	list_for_each_entry(cachep, &slab_caches, list) {

		l3 = cachep->nodelists[node];

		if (!l3)

			continue;
@@ -1225,7 +1219,7 @@ static int __cpuinit cpuup_prepare(long cpu) 
	 * Now we can go ahead with allocating the shared arrays and

	 * array caches

	 */

	list_for_each_entry(cachep, &cache_chain, list) {

	list_for_each_entry(cachep, &slab_caches, list) {

		struct array_cache *nc;

		struct array_cache *shared = NULL;

		struct array_cache **alien = NULL;
@@ -1293,9 +1287,9 @@ static int __cpuinit cpuup_callback(struct notifier_block *nfb, 
	switch (action) {

	case CPU_UP_PREPARE:

	case CPU_UP_PREPARE_FROZEN:

		mutex_lock(&cache_chain_mutex);

		mutex_lock(&slab_mutex);

		err = cpuup_prepare(cpu);

		mutex_unlock(&cache_chain_mutex);

		mutex_unlock(&slab_mutex);

		break;

	case CPU_ONLINE:

	case CPU_ONLINE_FROZEN:
@@ -1305,7 +1299,7 @@ static int __cpuinit cpuup_callback(struct notifier_block *nfb, 
  	case CPU_DOWN_PREPARE:

  	case CPU_DOWN_PREPARE_FROZEN:

		/*

		 * Shutdown cache reaper. Note that the cache_chain_mutex is

		 * 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.
@@ -1332,9 +1326,9 @@ static int __cpuinit cpuup_callback(struct notifier_block *nfb, 
#endif

	case CPU_UP_CANCELED:

	case CPU_UP_CANCELED_FROZEN:

		mutex_lock(&cache_chain_mutex);

		mutex_lock(&slab_mutex);

		cpuup_canceled(cpu);

		mutex_unlock(&cache_chain_mutex);

		mutex_unlock(&slab_mutex);

		break;

	}

	return notifier_from_errno(err);
@@ -1350,14 +1344,14 @@ static struct notifier_block __cpuinitdata cpucache_notifier = { 
 * Returns -EBUSY if all objects cannot be drained so that the node is not

 * removed.

 *

 * Must hold cache_chain_mutex.

 * Must hold slab_mutex.

 */

static int __meminit drain_cache_nodelists_node(int node)

{

	struct kmem_cache *cachep;

	int ret = 0;



	list_for_each_entry(cachep, &cache_chain, list) {

	list_for_each_entry(cachep, &slab_caches, list) {

		struct kmem_list3 *l3;



		l3 = cachep->nodelists[node];
@@ -1388,14 +1382,14 @@ static int __meminit slab_memory_callback(struct notifier_block *self, 


	switch (action) {

	case MEM_GOING_ONLINE:

		mutex_lock(&cache_chain_mutex);

		mutex_lock(&slab_mutex);

		ret = init_cache_nodelists_node(nid);

		mutex_unlock(&cache_chain_mutex);

		mutex_unlock(&slab_mutex);

		break;

	case MEM_GOING_OFFLINE:

		mutex_lock(&cache_chain_mutex);

		mutex_lock(&slab_mutex);

		ret = drain_cache_nodelists_node(nid);

		mutex_unlock(&cache_chain_mutex);

		mutex_unlock(&slab_mutex);

		break;

	case MEM_ONLINE:

	case MEM_OFFLINE:
@@ -1499,8 +1493,8 @@ void __init kmem_cache_init(void) 
	node = numa_mem_id();



	/* 1) create the cache_cache */

	INIT_LIST_HEAD(&cache_chain);

	list_add(&cache_cache.list, &cache_chain);

	INIT_LIST_HEAD(&slab_caches);

	list_add(&cache_cache.list, &slab_caches);

	cache_cache.colour_off = cache_line_size();

	cache_cache.array[smp_processor_id()] = &initarray_cache.cache;

	cache_cache.nodelists[node] = &initkmem_list3[CACHE_CACHE + node];
@@ -1642,11 +1636,11 @@ void __init kmem_cache_init_late(void) 
	init_lock_keys();



	/* 6) resize the head arrays to their final sizes */

	mutex_lock(&cache_chain_mutex);

	list_for_each_entry(cachep, &cache_chain, list)

	mutex_lock(&slab_mutex);

	list_for_each_entry(cachep, &slab_caches, list)

		if (enable_cpucache(cachep, GFP_NOWAIT))

			BUG();

	mutex_unlock(&cache_chain_mutex);

	mutex_unlock(&slab_mutex);



	/* Done! */

	slab_state = FULL;
@@ -2253,10 +2247,10 @@ __kmem_cache_create (const char *name, size_t size, size_t align, 
	 */

	if (slab_is_available()) {

		get_online_cpus();

		mutex_lock(&cache_chain_mutex);

		mutex_lock(&slab_mutex);

	}



	list_for_each_entry(pc, &cache_chain, list) {

	list_for_each_entry(pc, &slab_caches, list) {

		char tmp;

		int res;
@@ -2500,10 +2494,10 @@ __kmem_cache_create (const char *name, size_t size, size_t align, 
	}



	/* cache setup completed, link it into the list */

	list_add(&cachep->list, &cache_chain);

	list_add(&cachep->list, &slab_caches);

oops:

	if (slab_is_available()) {

		mutex_unlock(&cache_chain_mutex);

		mutex_unlock(&slab_mutex);

		put_online_cpus();

	}

	return cachep;
@@ -2622,7 +2616,7 @@ static int drain_freelist(struct kmem_cache *cache, 
	return nr_freed;

}



/* Called with cache_chain_mutex held to protect against cpu hotplug */

/* Called with slab_mutex held to protect against cpu hotplug */

static int __cache_shrink(struct kmem_cache *cachep)

{

	int ret = 0, i = 0;
@@ -2657,9 +2651,9 @@ int kmem_cache_shrink(struct kmem_cache *cachep) 
	BUG_ON(!cachep || in_interrupt());



	get_online_cpus();

	mutex_lock(&cache_chain_mutex);

	mutex_lock(&slab_mutex);

	ret = __cache_shrink(cachep);

	mutex_unlock(&cache_chain_mutex);

	mutex_unlock(&slab_mutex);

	put_online_cpus();

	return ret;

}
@@ -2687,15 +2681,15 @@ void kmem_cache_destroy(struct kmem_cache *cachep) 


	/* Find the cache in the chain of caches. */

	get_online_cpus();

	mutex_lock(&cache_chain_mutex);

	mutex_lock(&slab_mutex);

	/*

	 * the chain is never empty, cache_cache is never destroyed

	 */

	list_del(&cachep->list);

	if (__cache_shrink(cachep)) {

		slab_error(cachep, "Can't free all objects");

		list_add(&cachep->list, &cache_chain);

		mutex_unlock(&cache_chain_mutex);

		list_add(&cachep->list, &slab_caches);

		mutex_unlock(&slab_mutex);

		put_online_cpus();

		return;

	}
@@ -2704,7 +2698,7 @@ void kmem_cache_destroy(struct kmem_cache *cachep) 
		rcu_barrier();



	__kmem_cache_destroy(cachep);

	mutex_unlock(&cache_chain_mutex);

	mutex_unlock(&slab_mutex);

	put_online_cpus();

}

EXPORT_SYMBOL(kmem_cache_destroy);
@@ -4017,7 +4011,7 @@ static void do_ccupdate_local(void *info) 
	new->new[smp_processor_id()] = old;

}



/* Always called with the cache_chain_mutex held */

/* 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)

{
@@ -4061,7 +4055,7 @@ static int do_tune_cpucache(struct kmem_cache *cachep, int limit, 
	return alloc_kmemlist(cachep, gfp);

}



/* Called with cache_chain_mutex held always */

/* Called with slab_mutex held always */

static int enable_cpucache(struct kmem_cache *cachep, gfp_t gfp)

{

	int err;
@@ -4163,11 +4157,11 @@ static void cache_reap(struct work_struct *w) 
	int node = numa_mem_id();

	struct delayed_work *work = to_delayed_work(w);



	if (!mutex_trylock(&cache_chain_mutex))

	if (!mutex_trylock(&slab_mutex))

		/* Give up. Setup the next iteration. */

		goto out;



	list_for_each_entry(searchp, &cache_chain, list) {

	list_for_each_entry(searchp, &slab_caches, list) {

		check_irq_on();



		/*
@@ -4205,7 +4199,7 @@ static void cache_reap(struct work_struct *w) 
		cond_resched();

	}

	check_irq_on();

	mutex_unlock(&cache_chain_mutex);

	mutex_unlock(&slab_mutex);

	next_reap_node();

out:

	/* Set up the next iteration */
@@ -4241,21 +4235,21 @@ static void *s_start(struct seq_file *m, loff_t *pos) 
{

	loff_t n = *pos;



	mutex_lock(&cache_chain_mutex);

	mutex_lock(&slab_mutex);

	if (!n)

		print_slabinfo_header(m);



	return seq_list_start(&cache_chain, *pos);

	return seq_list_start(&slab_caches, *pos);

}



static void *s_next(struct seq_file *m, void *p, loff_t *pos)

{

	return seq_list_next(p, &cache_chain, pos);

	return seq_list_next(p, &slab_caches, pos);

}



static void s_stop(struct seq_file *m, void *p)

{

	mutex_unlock(&cache_chain_mutex);

	mutex_unlock(&slab_mutex);

}



static int s_show(struct seq_file *m, void *p)
@@ -4406,9 +4400,9 @@ static ssize_t slabinfo_write(struct file *file, const char __user *buffer, 
		return -EINVAL;



	/* Find the cache in the chain of caches. */

	mutex_lock(&cache_chain_mutex);

	mutex_lock(&slab_mutex);

	res = -EINVAL;

	list_for_each_entry(cachep, &cache_chain, list) {

	list_for_each_entry(cachep, &slab_caches, list) {

		if (!strcmp(cachep->name, kbuf)) {

			if (limit < 1 || batchcount < 1 ||

					batchcount > limit || shared < 0) {
@@ -4421,7 +4415,7 @@ static ssize_t slabinfo_write(struct file *file, const char __user *buffer, 
			break;

		}

	}

	mutex_unlock(&cache_chain_mutex);

	mutex_unlock(&slab_mutex);

	if (res >= 0)

		res = count;

	return res;
@@ -4444,8 +4438,8 @@ static const struct file_operations proc_slabinfo_operations = { 


static void *leaks_start(struct seq_file *m, loff_t *pos)

{

	mutex_lock(&cache_chain_mutex);

	return seq_list_start(&cache_chain, *pos);

	mutex_lock(&slab_mutex);

	return seq_list_start(&slab_caches, *pos);

}



static inline int add_caller(unsigned long *n, unsigned long v)
@@ -4544,17 +4538,17 @@ static int leaks_show(struct seq_file *m, void *p) 
	name = cachep->name;

	if (n[0] == n[1]) {

		/* Increase the buffer size */

		mutex_unlock(&cache_chain_mutex);

		mutex_unlock(&slab_mutex);

		m->private = kzalloc(n[0] * 4 * sizeof(unsigned long), GFP_KERNEL);

		if (!m->private) {

			/* Too bad, we are really out */

			m->private = n;

			mutex_lock(&cache_chain_mutex);

			mutex_lock(&slab_mutex);

			return -ENOMEM;

		}

		*(unsigned long *)m->private = n[0] * 2;

		kfree(n);

		mutex_lock(&cache_chain_mutex);

		mutex_lock(&slab_mutex);

		/* Now make sure this entry will be retried */

		m->count = m->size;

		return 0;

mm/slab.h

+4 −0
Original line number Diff line number Diff line
@@ -23,6 +23,10 @@ enum slab_state { 


extern enum slab_state slab_state;



/* The slab cache mutex protects the management structures during changes */

extern struct mutex slab_mutex;

extern struct list_head slab_caches;



struct kmem_cache *__kmem_cache_create(const char *name, size_t size,

	size_t align, unsigned long flags, void (*ctor)(void *));

mm/slab_common.c

+2 −0
Original line number Diff line number Diff line
@@ -19,6 +19,8 @@ 
#include "slab.h"



enum slab_state slab_state;

LIST_HEAD(slab_caches);

DEFINE_MUTEX(slab_mutex);



/*

 * kmem_cache_create - Create a cache.

mm/slub.c

+25 −29
Original line number Diff line number Diff line
@@ -36,13 +36,13 @@ 


/*

 * Lock order:

 *   1. slub_lock (Global Semaphore)

 *   1. slab_mutex (Global Mutex)

 *   2. node->list_lock

 *   3. slab_lock(page) (Only on some arches and for debugging)

 *

 *   slub_lock

 *   slab_mutex

 *

 *   The role of the slub_lock is to protect the list of all the slabs

 *   The role of the slab_mutex is to protect the list of all the slabs

 *   and to synchronize major metadata changes to slab cache structures.

 *

 *   The slab_lock is only used for debugging and on arches that do not
@@ -183,10 +183,6 @@ static int kmem_size = sizeof(struct kmem_cache); 
static struct notifier_block slab_notifier;

#endif



/* A list of all slab caches on the system */

static DECLARE_RWSEM(slub_lock);

static LIST_HEAD(slab_caches);



/*

 * Tracking user of a slab.

 */
@@ -3177,11 +3173,11 @@ static inline int kmem_cache_close(struct kmem_cache *s) 
 */

void kmem_cache_destroy(struct kmem_cache *s)

{

	down_write(&slub_lock);

	mutex_lock(&slab_mutex);

	s->refcount--;

	if (!s->refcount) {

		list_del(&s->list);

		up_write(&slub_lock);

		mutex_unlock(&slab_mutex);

		if (kmem_cache_close(s)) {

			printk(KERN_ERR "SLUB %s: %s called for cache that "

				"still has objects.\n", s->name, __func__);
@@ -3191,7 +3187,7 @@ void kmem_cache_destroy(struct kmem_cache *s) 
			rcu_barrier();

		sysfs_slab_remove(s);

	} else

		up_write(&slub_lock);

		mutex_unlock(&slab_mutex);

}

EXPORT_SYMBOL(kmem_cache_destroy);
@@ -3253,7 +3249,7 @@ static struct kmem_cache *__init create_kmalloc_cache(const char *name, 


	/*

	 * This function is called with IRQs disabled during early-boot on

	 * single CPU so there's no need to take slub_lock here.

	 * single CPU so there's no need to take slab_mutex here.

	 */

	if (!kmem_cache_open(s, name, size, ARCH_KMALLOC_MINALIGN,

								flags, NULL))
@@ -3538,10 +3534,10 @@ static int slab_mem_going_offline_callback(void *arg) 
{

	struct kmem_cache *s;



	down_read(&slub_lock);

	mutex_lock(&slab_mutex);

	list_for_each_entry(s, &slab_caches, list)

		kmem_cache_shrink(s);

	up_read(&slub_lock);

	mutex_unlock(&slab_mutex);



	return 0;

}
@@ -3562,7 +3558,7 @@ static void slab_mem_offline_callback(void *arg) 
	if (offline_node < 0)

		return;



	down_read(&slub_lock);

	mutex_lock(&slab_mutex);

	list_for_each_entry(s, &slab_caches, list) {

		n = get_node(s, offline_node);

		if (n) {
@@ -3578,7 +3574,7 @@ static void slab_mem_offline_callback(void *arg) 
			kmem_cache_free(kmem_cache_node, n);

		}

	}

	up_read(&slub_lock);

	mutex_unlock(&slab_mutex);

}



static int slab_mem_going_online_callback(void *arg)
@@ -3601,7 +3597,7 @@ static int slab_mem_going_online_callback(void *arg) 
	 * allocate a kmem_cache_node structure in order to bring the node

	 * online.

	 */

	down_read(&slub_lock);

	mutex_lock(&slab_mutex);

	list_for_each_entry(s, &slab_caches, list) {

		/*

		 * XXX: kmem_cache_alloc_node will fallback to other nodes
@@ -3617,7 +3613,7 @@ static int slab_mem_going_online_callback(void *arg) 
		s->node[nid] = n;

	}

out:

	up_read(&slub_lock);

	mutex_unlock(&slab_mutex);

	return ret;

}
@@ -3915,7 +3911,7 @@ struct kmem_cache *__kmem_cache_create(const char *name, size_t size, 
	struct kmem_cache *s;

	char *n;



	down_write(&slub_lock);

	mutex_lock(&slab_mutex);

	s = find_mergeable(size, align, flags, name, ctor);

	if (s) {

		s->refcount++;
@@ -3930,7 +3926,7 @@ struct kmem_cache *__kmem_cache_create(const char *name, size_t size, 
			s->refcount--;

			goto err;

		}

		up_write(&slub_lock);

		mutex_unlock(&slab_mutex);

		return s;

	}
@@ -3943,9 +3939,9 @@ struct kmem_cache *__kmem_cache_create(const char *name, size_t size, 
		if (kmem_cache_open(s, n,

				size, align, flags, ctor)) {

			list_add(&s->list, &slab_caches);

			up_write(&slub_lock);

			mutex_unlock(&slab_mutex);

			if (sysfs_slab_add(s)) {

				down_write(&slub_lock);

				mutex_lock(&slab_mutex);

				list_del(&s->list);

				kfree(n);

				kfree(s);
@@ -3957,7 +3953,7 @@ struct kmem_cache *__kmem_cache_create(const char *name, size_t size, 
	}

	kfree(n);

err:

	up_write(&slub_lock);

	mutex_unlock(&slab_mutex);

	return s;

}
@@ -3978,13 +3974,13 @@ static int __cpuinit slab_cpuup_callback(struct notifier_block *nfb, 
	case CPU_UP_CANCELED_FROZEN:

	case CPU_DEAD:

	case CPU_DEAD_FROZEN:

		down_read(&slub_lock);

		mutex_lock(&slab_mutex);

		list_for_each_entry(s, &slab_caches, list) {

			local_irq_save(flags);

			__flush_cpu_slab(s, cpu);

			local_irq_restore(flags);

		}

		up_read(&slub_lock);

		mutex_unlock(&slab_mutex);

		break;

	default:

		break;
@@ -5360,11 +5356,11 @@ static int __init slab_sysfs_init(void) 
	struct kmem_cache *s;

	int err;



	down_write(&slub_lock);

	mutex_lock(&slab_mutex);



	slab_kset = kset_create_and_add("slab", &slab_uevent_ops, kernel_kobj);

	if (!slab_kset) {

		up_write(&slub_lock);

		mutex_unlock(&slab_mutex);

		printk(KERN_ERR "Cannot register slab subsystem.\n");

		return -ENOSYS;

	}
@@ -5389,7 +5385,7 @@ static int __init slab_sysfs_init(void) 
		kfree(al);

	}



	up_write(&slub_lock);

	mutex_unlock(&slab_mutex);

	resiliency_test();

	return 0;

}
@@ -5415,7 +5411,7 @@ static void *s_start(struct seq_file *m, loff_t *pos) 
{

	loff_t n = *pos;



	down_read(&slub_lock);

	mutex_lock(&slab_mutex);

	if (!n)

		print_slabinfo_header(m);
@@ -5429,7 +5425,7 @@ static void *s_next(struct seq_file *m, void *p, loff_t *pos) 


static void s_stop(struct seq_file *m, void *p)

{

	up_read(&slub_lock);

	mutex_unlock(&slab_mutex);

}



static int s_show(struct seq_file *m, void *p)