* SLUB: A slab allocator that limits cache line use instead of queuing
* objects in per cpu and per node lists.
*
- * The allocator synchronizes using per slab locks and only
- * uses a centralized lock to manage a pool of partial slabs.
+ * The allocator synchronizes using per slab locks or atomic operatios
+ * and only uses a centralized lock to manage a pool of partial slabs.
*
* (C) 2007 SGI, Christoph Lameter
+ * (C) 2011 Linux Foundation, Christoph Lameter
*/
#include <linux/mm.h>
#include <linux/memory.h>
#include <linux/math64.h>
#include <linux/fault-inject.h>
+#include <linux/stacktrace.h>
#include <trace/events/kmem.h>
/*
* Lock order:
- * 1. slab_lock(page)
- * 2. slab->list_lock
+ * 1. slub_lock (Global Semaphore)
+ * 2. node->list_lock
+ * 3. slab_lock(page) (Only on some arches and for debugging)
*
- * The slab_lock protects operations on the object of a particular
- * slab and its metadata in the page struct. If the slab lock
- * has been taken then no allocations nor frees can be performed
- * on the objects in the slab nor can the slab be added or removed
- * from the partial or full lists since this would mean modifying
- * the page_struct of the slab.
+ * slub_lock
+ *
+ * The role of the slub_lock 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
+ * have the ability to do a cmpxchg_double. It only protects the second
+ * double word in the page struct. Meaning
+ * A. page->freelist -> List of object free in a page
+ * B. page->counters -> Counters of objects
+ * C. page->frozen -> frozen state
+ *
+ * If a slab is frozen then it is exempt from list management. It is not
+ * on any list. The processor that froze the slab is the one who can
+ * perform list operations on the page. Other processors may put objects
+ * onto the freelist but the processor that froze the slab is the only
+ * one that can retrieve the objects from the page's freelist.
*
* The list_lock protects the partial and full list on each node and
* the partial slab counter. If taken then no new slabs may be added or
* slabs, operations can continue without any centralized lock. F.e.
* allocating a long series of objects that fill up slabs does not require
* the list lock.
- *
- * The lock order is sometimes inverted when we are trying to get a slab
- * off a list. We take the list_lock and then look for a page on the list
- * to use. While we do that objects in the slabs may be freed. We can
- * only operate on the slab if we have also taken the slab_lock. So we use
- * a slab_trylock() on the slab. If trylock was successful then no frees
- * can occur anymore and we can use the slab for allocations etc. If the
- * slab_trylock() does not succeed then frees are in progress in the slab and
- * we must stay away from it for a while since we may cause a bouncing
- * cacheline if we try to acquire the lock. So go onto the next slab.
- * If all pages are busy then we may allocate a new slab instead of reusing
- * a partial slab. A new slab has no one operating on it and thus there is
- * no danger of cacheline contention.
- *
* Interrupts are disabled during allocation and deallocation in order to
* make the slab allocator safe to use in the context of an irq. In addition
* interrupts are disabled to ensure that the processor does not change
/* Enable to test recovery from slab corruption on boot */
#undef SLUB_RESILIENCY_TEST
+ /* Enable to log cmpxchg failures */
+ #undef SLUB_DEBUG_CMPXCHG
+
/*
* Mininum number of partial slabs. These will be left on the partial
* lists even if they are empty. kmem_cache_shrink may reclaim them.
#define OO_SHIFT 16
#define OO_MASK ((1 << OO_SHIFT) - 1)
- #define MAX_OBJS_PER_PAGE 65535 /* since page.objects is u16 */
+ #define MAX_OBJS_PER_PAGE 32767 /* since page.objects is u15 */
/* Internal SLUB flags */
#define __OBJECT_POISON 0x80000000UL /* Poison object */
+ #define __CMPXCHG_DOUBLE 0x40000000UL /* Use cmpxchg_double */
static int kmem_size = sizeof(struct kmem_cache);
/*
* Tracking user of a slab.
*/
+#define TRACK_ADDRS_COUNT 16
struct track {
unsigned long addr; /* Called from address */
+#ifdef CONFIG_STACKTRACE
+ unsigned long addrs[TRACK_ADDRS_COUNT]; /* Called from address */
+#endif
int cpu; /* Was running on cpu */
int pid; /* Pid context */
unsigned long when; /* When did the operation occur */
return x.x & OO_MASK;
}
+ /*
+ * Per slab locking using the pagelock
+ */
+ static __always_inline void slab_lock(struct page *page)
+ {
+ bit_spin_lock(PG_locked, &page->flags);
+ }
+
+ static __always_inline void slab_unlock(struct page *page)
+ {
+ __bit_spin_unlock(PG_locked, &page->flags);
+ }
+
+ /* Interrupts must be disabled (for the fallback code to work right) */
+ static inline bool __cmpxchg_double_slab(struct kmem_cache *s, struct page *page,
+ void *freelist_old, unsigned long counters_old,
+ void *freelist_new, unsigned long counters_new,
+ const char *n)
+ {
+ VM_BUG_ON(!irqs_disabled());
+ #ifdef CONFIG_CMPXCHG_DOUBLE
+ if (s->flags & __CMPXCHG_DOUBLE) {
+ if (cmpxchg_double(&page->freelist,
+ freelist_old, counters_old,
+ freelist_new, counters_new))
+ return 1;
+ } else
+ #endif
+ {
+ slab_lock(page);
+ if (page->freelist == freelist_old && page->counters == counters_old) {
+ page->freelist = freelist_new;
+ page->counters = counters_new;
+ slab_unlock(page);
+ return 1;
+ }
+ slab_unlock(page);
+ }
+
+ cpu_relax();
+ stat(s, CMPXCHG_DOUBLE_FAIL);
+
+ #ifdef SLUB_DEBUG_CMPXCHG
+ printk(KERN_INFO "%s %s: cmpxchg double redo ", n, s->name);
+ #endif
+
+ return 0;
+ }
+
+ static inline bool cmpxchg_double_slab(struct kmem_cache *s, struct page *page,
+ void *freelist_old, unsigned long counters_old,
+ void *freelist_new, unsigned long counters_new,
+ const char *n)
+ {
+ #ifdef CONFIG_CMPXCHG_DOUBLE
+ if (s->flags & __CMPXCHG_DOUBLE) {
+ if (cmpxchg_double(&page->freelist,
+ freelist_old, counters_old,
+ freelist_new, counters_new))
+ return 1;
+ } else
+ #endif
+ {
+ unsigned long flags;
+
+ local_irq_save(flags);
+ slab_lock(page);
+ if (page->freelist == freelist_old && page->counters == counters_old) {
+ page->freelist = freelist_new;
+ page->counters = counters_new;
+ slab_unlock(page);
+ local_irq_restore(flags);
+ return 1;
+ }
+ slab_unlock(page);
+ local_irq_restore(flags);
+ }
+
+ cpu_relax();
+ stat(s, CMPXCHG_DOUBLE_FAIL);
+
+ #ifdef SLUB_DEBUG_CMPXCHG
+ printk(KERN_INFO "%s %s: cmpxchg double redo ", n, s->name);
+ #endif
+
+ return 0;
+ }
+
#ifdef CONFIG_SLUB_DEBUG
/*
* Determine a map of object in use on a page.
*
- * Slab lock or node listlock must be held to guarantee that the page does
+ * Node listlock must be held to guarantee that the page does
* not vanish from under us.
*/
static void get_map(struct kmem_cache *s, struct page *page, unsigned long *map)
struct track *p = get_track(s, object, alloc);
if (addr) {
+#ifdef CONFIG_STACKTRACE
+ struct stack_trace trace;
+ int i;
+
+ trace.nr_entries = 0;
+ trace.max_entries = TRACK_ADDRS_COUNT;
+ trace.entries = p->addrs;
+ trace.skip = 3;
+ save_stack_trace(&trace);
+
+ /* See rant in lockdep.c */
+ if (trace.nr_entries != 0 &&
+ trace.entries[trace.nr_entries - 1] == ULONG_MAX)
+ trace.nr_entries--;
+
+ for (i = trace.nr_entries; i < TRACK_ADDRS_COUNT; i++)
+ p->addrs[i] = 0;
+#endif
p->addr = addr;
p->cpu = smp_processor_id();
p->pid = current->pid;
printk(KERN_ERR "INFO: %s in %pS age=%lu cpu=%u pid=%d\n",
s, (void *)t->addr, jiffies - t->when, t->cpu, t->pid);
+#ifdef CONFIG_STACKTRACE
+ {
+ int i;
+ for (i = 0; i < TRACK_ADDRS_COUNT; i++)
+ if (t->addrs[i])
+ printk(KERN_ERR "\t%pS\n", (void *)t->addrs[i]);
+ else
+ break;
+ }
+#endif
}
static void print_tracking(struct kmem_cache *s, void *object)
memset(p + s->objsize, val, s->inuse - s->objsize);
}
-static u8 *check_bytes(u8 *start, unsigned int value, unsigned int bytes)
+static u8 *check_bytes8(u8 *start, u8 value, unsigned int bytes)
{
while (bytes) {
- if (*start != (u8)value)
+ if (*start != value)
return start;
start++;
bytes--;
return NULL;
}
+static u8 *check_bytes(u8 *start, u8 value, unsigned int bytes)
+{
+ u64 value64;
+ unsigned int words, prefix;
+
+ if (bytes <= 16)
+ return check_bytes8(start, value, bytes);
+
+ value64 = value | value << 8 | value << 16 | value << 24;
+ value64 = value64 | value64 << 32;
+ prefix = 8 - ((unsigned long)start) % 8;
+
+ if (prefix) {
+ u8 *r = check_bytes8(start, value, prefix);
+ if (r)
+ return r;
+ start += prefix;
+ bytes -= prefix;
+ }
+
+ words = bytes / 8;
+
+ while (words) {
+ if (*(u64 *)start != value64)
+ return check_bytes8(start, value, 8);
+ start += 8;
+ words--;
+ }
+
+ return check_bytes8(start, value, bytes % 8);
+}
+
static void restore_bytes(struct kmem_cache *s, char *message, u8 data,
void *from, void *to)
{
static int on_freelist(struct kmem_cache *s, struct page *page, void *search)
{
int nr = 0;
- void *fp = page->freelist;
+ void *fp;
void *object = NULL;
unsigned long max_objects;
+ fp = page->freelist;
while (fp && nr <= page->objects) {
if (fp == search)
return 1;
/*
* Tracking of fully allocated slabs for debugging purposes.
+ *
+ * list_lock must be held.
*/
- static void add_full(struct kmem_cache_node *n, struct page *page)
+ static void add_full(struct kmem_cache *s,
+ struct kmem_cache_node *n, struct page *page)
{
- spin_lock(&n->list_lock);
+ if (!(s->flags & SLAB_STORE_USER))
+ return;
+
list_add(&page->lru, &n->full);
- spin_unlock(&n->list_lock);
}
+ /*
+ * list_lock must be held.
+ */
static void remove_full(struct kmem_cache *s, struct page *page)
{
- struct kmem_cache_node *n;
-
if (!(s->flags & SLAB_STORE_USER))
return;
- n = get_node(s, page_to_nid(page));
-
- spin_lock(&n->list_lock);
list_del(&page->lru);
- spin_unlock(&n->list_lock);
}
/* Tracking of the number of slabs for debugging purposes */
if (!check_slab(s, page))
goto bad;
- if (!on_freelist(s, page, object)) {
- object_err(s, page, object, "Object already allocated");
- goto bad;
- }
-
if (!check_valid_pointer(s, page, object)) {
object_err(s, page, object, "Freelist Pointer check fails");
goto bad;
static noinline int free_debug_processing(struct kmem_cache *s,
struct page *page, void *object, unsigned long addr)
{
+ unsigned long flags;
+ int rc = 0;
+
+ local_irq_save(flags);
+ slab_lock(page);
+
if (!check_slab(s, page))
goto fail;
}
if (!check_object(s, page, object, SLUB_RED_ACTIVE))
- return 0;
+ goto out;
if (unlikely(s != page->slab)) {
if (!PageSlab(page)) {
goto fail;
}
- /* Special debug activities for freeing objects */
- if (!PageSlubFrozen(page) && !page->freelist)
- remove_full(s, page);
if (s->flags & SLAB_STORE_USER)
set_track(s, object, TRACK_FREE, addr);
trace(s, page, object, 0);
init_object(s, object, SLUB_RED_INACTIVE);
- return 1;
+ rc = 1;
+ out:
+ slab_unlock(page);
+ local_irq_restore(flags);
+ return rc;
fail:
slab_fix(s, "Object at 0x%p not freed", object);
- return 0;
+ goto out;
}
static int __init setup_slub_debug(char *str)
{ return 1; }
static inline int check_object(struct kmem_cache *s, struct page *page,
void *object, u8 val) { return 1; }
- static inline void add_full(struct kmem_cache_node *n, struct page *page) {}
+ static inline void add_full(struct kmem_cache *s, struct kmem_cache_node *n,
+ struct page *page) {}
+ static inline void remove_full(struct kmem_cache *s, struct page *page) {}
static inline unsigned long kmem_cache_flags(unsigned long objsize,
unsigned long flags, const char *name,
void (*ctor)(void *))
struct kmem_cache_order_objects oo = s->oo;
gfp_t alloc_gfp;
+ flags &= gfp_allowed_mask;
+
+ if (flags & __GFP_WAIT)
+ local_irq_enable();
+
flags |= s->allocflags;
/*
* Try a lower order alloc if possible
*/
page = alloc_slab_page(flags, node, oo);
- if (!page)
- return NULL;
- stat(s, ORDER_FALLBACK);
+ if (page)
+ stat(s, ORDER_FALLBACK);
}
+ if (flags & __GFP_WAIT)
+ local_irq_disable();
+
+ if (!page)
+ return NULL;
+
if (kmemcheck_enabled
&& !(s->flags & (SLAB_NOTRACK | DEBUG_DEFAULT_FLAGS))) {
int pages = 1 << oo_order(oo);
page->freelist = start;
page->inuse = 0;
+ page->frozen = 1;
out:
return page;
}
}
/*
- * Per slab locking using the pagelock
- */
- static __always_inline void slab_lock(struct page *page)
- {
- bit_spin_lock(PG_locked, &page->flags);
- }
-
- static __always_inline void slab_unlock(struct page *page)
- {
- __bit_spin_unlock(PG_locked, &page->flags);
- }
-
- static __always_inline int slab_trylock(struct page *page)
- {
- int rc = 1;
-
- rc = bit_spin_trylock(PG_locked, &page->flags);
- return rc;
- }
-
- /*
- * Management of partially allocated slabs
+ * Management of partially allocated slabs.
+ *
+ * list_lock must be held.
*/
- static void add_partial(struct kmem_cache_node *n,
+ static inline void add_partial(struct kmem_cache_node *n,
struct page *page, int tail)
{
- spin_lock(&n->list_lock);
n->nr_partial++;
if (tail)
list_add_tail(&page->lru, &n->partial);
else
list_add(&page->lru, &n->partial);
- spin_unlock(&n->list_lock);
}
- static inline void __remove_partial(struct kmem_cache_node *n,
+ /*
+ * list_lock must be held.
+ */
+ static inline void remove_partial(struct kmem_cache_node *n,
struct page *page)
{
list_del(&page->lru);
n->nr_partial--;
}
- static void remove_partial(struct kmem_cache *s, struct page *page)
- {
- struct kmem_cache_node *n = get_node(s, page_to_nid(page));
-
- spin_lock(&n->list_lock);
- __remove_partial(n, page);
- spin_unlock(&n->list_lock);
- }
-
/*
- * Lock slab and remove from the partial list.
+ * Lock slab, remove from the partial list and put the object into the
+ * per cpu freelist.
*
* Must hold list_lock.
*/
- static inline int lock_and_freeze_slab(struct kmem_cache_node *n,
- struct page *page)
+ static inline int acquire_slab(struct kmem_cache *s,
+ struct kmem_cache_node *n, struct page *page)
{
- if (slab_trylock(page)) {
- __remove_partial(n, page);
- __SetPageSlubFrozen(page);
+ void *freelist;
+ unsigned long counters;
+ struct page new;
+
+ /*
+ * Zap the freelist and set the frozen bit.
+ * The old freelist is the list of objects for the
+ * per cpu allocation list.
+ */
+ do {
+ freelist = page->freelist;
+ counters = page->counters;
+ new.counters = counters;
+ new.inuse = page->objects;
+
+ VM_BUG_ON(new.frozen);
+ new.frozen = 1;
+
+ } while (!__cmpxchg_double_slab(s, page,
+ freelist, counters,
+ NULL, new.counters,
+ "lock and freeze"));
+
+ remove_partial(n, page);
+
+ if (freelist) {
+ /* Populate the per cpu freelist */
+ this_cpu_write(s->cpu_slab->freelist, freelist);
+ this_cpu_write(s->cpu_slab->page, page);
+ this_cpu_write(s->cpu_slab->node, page_to_nid(page));
return 1;
+ } else {
+ /*
+ * Slab page came from the wrong list. No object to allocate
+ * from. Put it onto the correct list and continue partial
+ * scan.
+ */
+ printk(KERN_ERR "SLUB: %s : Page without available objects on"
+ " partial list\n", s->name);
+ return 0;
}
- return 0;
}
/*
* Try to allocate a partial slab from a specific node.
*/
- static struct page *get_partial_node(struct kmem_cache_node *n)
+ static struct page *get_partial_node(struct kmem_cache *s,
+ struct kmem_cache_node *n)
{
struct page *page;
spin_lock(&n->list_lock);
list_for_each_entry(page, &n->partial, lru)
- if (lock_and_freeze_slab(n, page))
+ if (acquire_slab(s, n, page))
goto out;
page = NULL;
out:
if (n && cpuset_zone_allowed_hardwall(zone, flags) &&
n->nr_partial > s->min_partial) {
- page = get_partial_node(n);
+ page = get_partial_node(s, n);
if (page) {
put_mems_allowed();
return page;
struct page *page;
int searchnode = (node == NUMA_NO_NODE) ? numa_node_id() : node;
- page = get_partial_node(get_node(s, searchnode));
+ page = get_partial_node(s, get_node(s, searchnode));
if (page || node != NUMA_NO_NODE)
return page;
return get_any_partial(s, flags);
}
- /*
- * Move a page back to the lists.
- *
- * Must be called with the slab lock held.
- *
- * On exit the slab lock will have been dropped.
- */
- static void unfreeze_slab(struct kmem_cache *s, struct page *page, int tail)
- __releases(bitlock)
- {
- struct kmem_cache_node *n = get_node(s, page_to_nid(page));
-
- __ClearPageSlubFrozen(page);
- if (page->inuse) {
-
- if (page->freelist) {
- add_partial(n, page, tail);
- stat(s, tail ? DEACTIVATE_TO_TAIL : DEACTIVATE_TO_HEAD);
- } else {
- stat(s, DEACTIVATE_FULL);
- if (kmem_cache_debug(s) && (s->flags & SLAB_STORE_USER))
- add_full(n, page);
- }
- slab_unlock(page);
- } else {
- stat(s, DEACTIVATE_EMPTY);
- if (n->nr_partial < s->min_partial) {
- /*
- * Adding an empty slab to the partial slabs in order
- * to avoid page allocator overhead. This slab needs
- * to come after the other slabs with objects in
- * so that the others get filled first. That way the
- * size of the partial list stays small.
- *
- * kmem_cache_shrink can reclaim any empty slabs from
- * the partial list.
- */
- add_partial(n, page, 1);
- slab_unlock(page);
- } else {
- slab_unlock(page);
- stat(s, FREE_SLAB);
- discard_slab(s, page);
- }
- }
- }
-
#ifdef CONFIG_PREEMPT
/*
* Calculate the next globally unique transaction for disambiguiation
for_each_possible_cpu(cpu)
per_cpu_ptr(s->cpu_slab, cpu)->tid = init_tid(cpu);
}
+ /*
+ * Remove the cpu slab
+ */
+
/*
* Remove the cpu slab
*/
static void deactivate_slab(struct kmem_cache *s, struct kmem_cache_cpu *c)
- __releases(bitlock)
{
+ enum slab_modes { M_NONE, M_PARTIAL, M_FULL, M_FREE };
struct page *page = c->page;
- int tail = 1;
-
- if (page->freelist)
+ struct kmem_cache_node *n = get_node(s, page_to_nid(page));
+ int lock = 0;
+ enum slab_modes l = M_NONE, m = M_NONE;
+ void *freelist;
+ void *nextfree;
+ int tail = 0;
+ struct page new;
+ struct page old;
+
+ if (page->freelist) {
stat(s, DEACTIVATE_REMOTE_FREES);
+ tail = 1;
+ }
+
+ c->tid = next_tid(c->tid);
+ c->page = NULL;
+ freelist = c->freelist;
+ c->freelist = NULL;
+
+ /*
+ * Stage one: Free all available per cpu objects back
+ * to the page freelist while it is still frozen. Leave the
+ * last one.
+ *
+ * There is no need to take the list->lock because the page
+ * is still frozen.
+ */
+ while (freelist && (nextfree = get_freepointer(s, freelist))) {
+ void *prior;
+ unsigned long counters;
+
+ do {
+ prior = page->freelist;
+ counters = page->counters;
+ set_freepointer(s, freelist, prior);
+ new.counters = counters;
+ new.inuse--;
+ VM_BUG_ON(!new.frozen);
+
+ } while (!__cmpxchg_double_slab(s, page,
+ prior, counters,
+ freelist, new.counters,
+ "drain percpu freelist"));
+
+ freelist = nextfree;
+ }
+
/*
- * Merge cpu freelist into slab freelist. Typically we get here
- * because both freelists are empty. So this is unlikely
- * to occur.
+ * Stage two: Ensure that the page is unfrozen while the
+ * list presence reflects the actual number of objects
+ * during unfreeze.
+ *
+ * We setup the list membership and then perform a cmpxchg
+ * with the count. If there is a mismatch then the page
+ * is not unfrozen but the page is on the wrong list.
+ *
+ * Then we restart the process which may have to remove
+ * the page from the list that we just put it on again
+ * because the number of objects in the slab may have
+ * changed.
*/
- while (unlikely(c->freelist)) {
- void **object;
+ redo:
- tail = 0; /* Hot objects. Put the slab first */
+ old.freelist = page->freelist;
+ old.counters = page->counters;
+ VM_BUG_ON(!old.frozen);
- /* Retrieve object from cpu_freelist */
- object = c->freelist;
- c->freelist = get_freepointer(s, c->freelist);
+ /* Determine target state of the slab */
+ new.counters = old.counters;
+ if (freelist) {
+ new.inuse--;
+ set_freepointer(s, freelist, old.freelist);
+ new.freelist = freelist;
+ } else
+ new.freelist = old.freelist;
+
+ new.frozen = 0;
+
+ if (!new.inuse && n->nr_partial < s->min_partial)
+ m = M_FREE;
+ else if (new.freelist) {
+ m = M_PARTIAL;
+ if (!lock) {
+ lock = 1;
+ /*
+ * Taking the spinlock removes the possiblity
+ * that acquire_slab() will see a slab page that
+ * is frozen
+ */
+ spin_lock(&n->list_lock);
+ }
+ } else {
+ m = M_FULL;
+ if (kmem_cache_debug(s) && !lock) {
+ lock = 1;
+ /*
+ * This also ensures that the scanning of full
+ * slabs from diagnostic functions will not see
+ * any frozen slabs.
+ */
+ spin_lock(&n->list_lock);
+ }
+ }
+
+ if (l != m) {
+
+ if (l == M_PARTIAL)
+
+ remove_partial(n, page);
+
+ else if (l == M_FULL)
+
+ remove_full(s, page);
+
+ if (m == M_PARTIAL) {
+
+ add_partial(n, page, tail);
+ stat(s, tail ? DEACTIVATE_TO_TAIL : DEACTIVATE_TO_HEAD);
+
+ } else if (m == M_FULL) {
- /* And put onto the regular freelist */
- set_freepointer(s, object, page->freelist);
- page->freelist = object;
- page->inuse--;
+ stat(s, DEACTIVATE_FULL);
+ add_full(s, n, page);
+
+ }
+ }
+
+ l = m;
+ if (!__cmpxchg_double_slab(s, page,
+ old.freelist, old.counters,
+ new.freelist, new.counters,
+ "unfreezing slab"))
+ goto redo;
+
+ if (lock)
+ spin_unlock(&n->list_lock);
+
+ if (m == M_FREE) {
+ stat(s, DEACTIVATE_EMPTY);
+ discard_slab(s, page);
+ stat(s, FREE_SLAB);
}
- c->page = NULL;
- c->tid = next_tid(c->tid);
- unfreeze_slab(s, page, tail);
}
static inline void flush_slab(struct kmem_cache *s, struct kmem_cache_cpu *c)
{
stat(s, CPUSLAB_FLUSH);
- slab_lock(c->page);
deactivate_slab(s, c);
}
void **object;
struct page *page;
unsigned long flags;
+ struct page new;
+ unsigned long counters;
local_irq_save(flags);
#ifdef CONFIG_PREEMPT
if (!page)
goto new_slab;
- slab_lock(page);
- if (unlikely(!node_match(c, node)))
- goto another_slab;
+ if (unlikely(!node_match(c, node))) {
+ stat(s, ALLOC_NODE_MISMATCH);
+ deactivate_slab(s, c);
+ goto new_slab;
+ }
+
+ stat(s, ALLOC_SLOWPATH);
+
+ do {
+ object = page->freelist;
+ counters = page->counters;
+ new.counters = counters;
+ VM_BUG_ON(!new.frozen);
+
+ /*
+ * If there is no object left then we use this loop to
+ * deactivate the slab which is simple since no objects
+ * are left in the slab and therefore we do not need to
+ * put the page back onto the partial list.
+ *
+ * If there are objects left then we retrieve them
+ * and use them to refill the per cpu queue.
+ */
+
+ new.inuse = page->objects;
+ new.frozen = object != NULL;
+
+ } while (!__cmpxchg_double_slab(s, page,
+ object, counters,
+ NULL, new.counters,
+ "__slab_alloc"));
+
+ if (unlikely(!object)) {
+ c->page = NULL;
+ stat(s, DEACTIVATE_BYPASS);
+ goto new_slab;
+ }
stat(s, ALLOC_REFILL);
load_freelist:
- object = page->freelist;
- if (unlikely(!object))
- goto another_slab;
- if (kmem_cache_debug(s))
- goto debug;
-
+ VM_BUG_ON(!page->frozen);
c->freelist = get_freepointer(s, object);
- page->inuse = page->objects;
- page->freelist = NULL;
-
- slab_unlock(page);
c->tid = next_tid(c->tid);
local_irq_restore(flags);
- stat(s, ALLOC_SLOWPATH);
return object;
- another_slab:
- deactivate_slab(s, c);
-
new_slab:
page = get_partial(s, gfpflags, node);
if (page) {
stat(s, ALLOC_FROM_PARTIAL);
- c->node = page_to_nid(page);
- c->page = page;
+ object = c->freelist;
+
+ if (kmem_cache_debug(s))
+ goto debug;
goto load_freelist;
}
- gfpflags &= gfp_allowed_mask;
- if (gfpflags & __GFP_WAIT)
- local_irq_enable();
-
page = new_slab(s, gfpflags, node);
- if (gfpflags & __GFP_WAIT)
- local_irq_disable();
-
if (page) {
c = __this_cpu_ptr(s->cpu_slab);
- stat(s, ALLOC_SLAB);
if (c->page)
flush_slab(s, c);
- slab_lock(page);
- __SetPageSlubFrozen(page);
+ /*
+ * No other reference to the page yet so we can
+ * muck around with it freely without cmpxchg
+ */
+ object = page->freelist;
+ page->freelist = NULL;
+ page->inuse = page->objects;
+
+ stat(s, ALLOC_SLAB);
c->node = page_to_nid(page);
c->page = page;
+
+ if (kmem_cache_debug(s))
+ goto debug;
goto load_freelist;
}
if (!(gfpflags & __GFP_NOWARN) && printk_ratelimit())
slab_out_of_memory(s, gfpflags, node);
local_irq_restore(flags);
return NULL;
+
debug:
- if (!alloc_debug_processing(s, page, object, addr))
- goto another_slab;
+ if (!object || !alloc_debug_processing(s, page, object, addr))
+ goto new_slab;
- page->inuse++;
- page->freelist = get_freepointer(s, object);
+ c->freelist = get_freepointer(s, object);
deactivate_slab(s, c);
c->page = NULL;
c->node = NUMA_NO_NODE;
{
void *prior;
void **object = (void *)x;
- unsigned long flags;
+ int was_frozen;
+ int inuse;
+ struct page new;
+ unsigned long counters;
+ struct kmem_cache_node *n = NULL;
+ unsigned long uninitialized_var(flags);
- local_irq_save(flags);
- slab_lock(page);
stat(s, FREE_SLOWPATH);
if (kmem_cache_debug(s) && !free_debug_processing(s, page, x, addr))
- goto out_unlock;
+ return;
- prior = page->freelist;
- set_freepointer(s, object, prior);
- page->freelist = object;
- page->inuse--;
+ do {
+ prior = page->freelist;
+ counters = page->counters;
+ set_freepointer(s, object, prior);
+ new.counters = counters;
+ was_frozen = new.frozen;
+ new.inuse--;
+ if ((!new.inuse || !prior) && !was_frozen && !n) {
+ n = get_node(s, page_to_nid(page));
+ /*
+ * Speculatively acquire the list_lock.
+ * If the cmpxchg does not succeed then we may
+ * drop the list_lock without any processing.
+ *
+ * Otherwise the list_lock will synchronize with
+ * other processors updating the list of slabs.
+ */
+ spin_lock_irqsave(&n->list_lock, flags);
+ }
+ inuse = new.inuse;
- if (unlikely(PageSlubFrozen(page))) {
- stat(s, FREE_FROZEN);
- goto out_unlock;
- }
+ } while (!cmpxchg_double_slab(s, page,
+ prior, counters,
+ object, new.counters,
+ "__slab_free"));
- if (unlikely(!page->inuse))
- goto slab_empty;
+ if (likely(!n)) {
+ /*
+ * The list lock was not taken therefore no list
+ * activity can be necessary.
+ */
+ if (was_frozen)
+ stat(s, FREE_FROZEN);
+ return;
+ }
/*
- * Objects left in the slab. If it was not on the partial list before
- * then add it.
+ * was_frozen may have been set after we acquired the list_lock in
+ * an earlier loop. So we need to check it here again.
*/
- if (unlikely(!prior)) {
- add_partial(get_node(s, page_to_nid(page)), page, 1);
- stat(s, FREE_ADD_PARTIAL);
- }
+ if (was_frozen)
+ stat(s, FREE_FROZEN);
+ else {
+ if (unlikely(!inuse && n->nr_partial > s->min_partial))
+ goto slab_empty;
- out_unlock:
- slab_unlock(page);
- local_irq_restore(flags);
+ /*
+ * Objects left in the slab. If it was not on the partial list before
+ * then add it.
+ */
+ if (unlikely(!prior)) {
+ remove_full(s, page);
+ add_partial(n, page, 0);
+ stat(s, FREE_ADD_PARTIAL);
+ }
+ }
+ spin_unlock_irqrestore(&n->list_lock, flags);
return;
slab_empty:
/*
* Slab still on the partial list.
*/
- remove_partial(s, page);
+ remove_partial(n, page);
stat(s, FREE_REMOVE_PARTIAL);
}
- slab_unlock(page);
- local_irq_restore(flags);
+
+ spin_unlock_irqrestore(&n->list_lock, flags);
stat(s, FREE_SLAB);
discard_slab(s, page);
}
{
struct page *page;
struct kmem_cache_node *n;
- unsigned long flags;
BUG_ON(kmem_cache_node->size < sizeof(struct kmem_cache_node));
BUG_ON(!n);
page->freelist = get_freepointer(kmem_cache_node, n);
page->inuse++;
+ page->frozen = 0;
kmem_cache_node->node[node] = n;
#ifdef CONFIG_SLUB_DEBUG
init_object(kmem_cache_node, n, SLUB_RED_ACTIVE);
init_kmem_cache_node(n, kmem_cache_node);
inc_slabs_node(kmem_cache_node, node, page->objects);
- /*
- * lockdep requires consistent irq usage for each lock
- * so even though there cannot be a race this early in
- * the boot sequence, we still disable irqs.
- */
- local_irq_save(flags);
add_partial(n, page, 0);
- local_irq_restore(flags);
}
static void free_kmem_cache_nodes(struct kmem_cache *s)
}
}
+ #ifdef CONFIG_CMPXCHG_DOUBLE
+ if (system_has_cmpxchg_double() && (s->flags & SLAB_DEBUG_FLAGS) == 0)
+ /* Enable fast mode */
+ s->flags |= __CMPXCHG_DOUBLE;
+ #endif
+
/*
* The larger the object size is, the more pages we want on the partial
* list to avoid pounding the page allocator excessively.
spin_lock_irqsave(&n->list_lock, flags);
list_for_each_entry_safe(page, h, &n->partial, lru) {
if (!page->inuse) {
- __remove_partial(n, page);
+ remove_partial(n, page);
discard_slab(s, page);
} else {
list_slab_objects(s, page,
}
EXPORT_SYMBOL(ksize);
+#ifdef CONFIG_SLUB_DEBUG
+bool verify_mem_not_deleted(const void *x)
+{
+ struct page *page;
+ void *object = (void *)x;
+ unsigned long flags;
+ bool rv;
+
+ if (unlikely(ZERO_OR_NULL_PTR(x)))
+ return false;
+
+ local_irq_save(flags);
+
+ page = virt_to_head_page(x);
+ if (unlikely(!PageSlab(page))) {
+ /* maybe it was from stack? */
+ rv = true;
+ goto out_unlock;
+ }
+
+ slab_lock(page);
+ if (on_freelist(page->slab, page, object)) {
+ object_err(page->slab, page, object, "Object is on free-list");
+ rv = false;
+ } else {
+ rv = true;
+ }
+ slab_unlock(page);
+
+out_unlock:
+ local_irq_restore(flags);
+ return rv;
+}
+EXPORT_SYMBOL(verify_mem_not_deleted);
+#endif
+
void kfree(const void *x)
{
struct page *page;
* list_lock. page->inuse here is the upper limit.
*/
list_for_each_entry_safe(page, t, &n->partial, lru) {
- if (!page->inuse && slab_trylock(page)) {
- /*
- * Must hold slab lock here because slab_free
- * may have freed the last object and be
- * waiting to release the slab.
- */
- __remove_partial(n, page);
- slab_unlock(page);
+ if (!page->inuse) {
+ remove_partial(n, page);
discard_slab(s, page);
} else {
list_move(&page->lru,
static void validate_slab_slab(struct kmem_cache *s, struct page *page,
unsigned long *map)
{
- if (slab_trylock(page)) {
- validate_slab(s, page, map);
- slab_unlock(page);
- } else
- printk(KERN_INFO "SLUB %s: Skipped busy slab 0x%p\n",
- s->name, page);
+ slab_lock(page);
+ validate_slab(s, page, map);
+ slab_unlock(page);
}
static int validate_slab_node(struct kmem_cache *s,
#endif
#define to_slab_attr(n) container_of(n, struct slab_attribute, attr)
-#define to_slab(n) container_of(n, struct kmem_cache, kobj);
+#define to_slab(n) container_of(n, struct kmem_cache, kobj)
struct slab_attribute {
struct attribute attr;
const char *buf, size_t length)
{
s->flags &= ~SLAB_DEBUG_FREE;
- if (buf[0] == '1')
+ if (buf[0] == '1') {
+ s->flags &= ~__CMPXCHG_DOUBLE;
s->flags |= SLAB_DEBUG_FREE;
+ }
return length;
}
SLAB_ATTR(sanity_checks);
size_t length)
{
s->flags &= ~SLAB_TRACE;
- if (buf[0] == '1')
+ if (buf[0] == '1') {
+ s->flags &= ~__CMPXCHG_DOUBLE;
s->flags |= SLAB_TRACE;
+ }
return length;
}
SLAB_ATTR(trace);
return -EBUSY;
s->flags &= ~SLAB_RED_ZONE;
- if (buf[0] == '1')
+ if (buf[0] == '1') {
+ s->flags &= ~__CMPXCHG_DOUBLE;
s->flags |= SLAB_RED_ZONE;
+ }
calculate_sizes(s, -1);
return length;
}
return -EBUSY;
s->flags &= ~SLAB_POISON;
- if (buf[0] == '1')
+ if (buf[0] == '1') {
+ s->flags &= ~__CMPXCHG_DOUBLE;
s->flags |= SLAB_POISON;
+ }
calculate_sizes(s, -1);
return length;
}
return -EBUSY;
s->flags &= ~SLAB_STORE_USER;
- if (buf[0] == '1')
+ if (buf[0] == '1') {
+ s->flags &= ~__CMPXCHG_DOUBLE;
s->flags |= SLAB_STORE_USER;
+ }
calculate_sizes(s, -1);
return length;
}
STAT_ATTR(ALLOC_FROM_PARTIAL, alloc_from_partial);
STAT_ATTR(ALLOC_SLAB, alloc_slab);
STAT_ATTR(ALLOC_REFILL, alloc_refill);
+ STAT_ATTR(ALLOC_NODE_MISMATCH, alloc_node_mismatch);
STAT_ATTR(FREE_SLAB, free_slab);
STAT_ATTR(CPUSLAB_FLUSH, cpuslab_flush);
STAT_ATTR(DEACTIVATE_FULL, deactivate_full);
STAT_ATTR(DEACTIVATE_TO_HEAD, deactivate_to_head);
STAT_ATTR(DEACTIVATE_TO_TAIL, deactivate_to_tail);
STAT_ATTR(DEACTIVATE_REMOTE_FREES, deactivate_remote_frees);
+ STAT_ATTR(DEACTIVATE_BYPASS, deactivate_bypass);
STAT_ATTR(ORDER_FALLBACK, order_fallback);
+ STAT_ATTR(CMPXCHG_DOUBLE_CPU_FAIL, cmpxchg_double_cpu_fail);
+ STAT_ATTR(CMPXCHG_DOUBLE_FAIL, cmpxchg_double_fail);
#endif
static struct attribute *slab_attrs[] = {
&alloc_from_partial_attr.attr,
&alloc_slab_attr.attr,
&alloc_refill_attr.attr,
+ &alloc_node_mismatch_attr.attr,
&free_slab_attr.attr,
&cpuslab_flush_attr.attr,
&deactivate_full_attr.attr,
&deactivate_to_head_attr.attr,
&deactivate_to_tail_attr.attr,
&deactivate_remote_frees_attr.attr,
+ &deactivate_bypass_attr.attr,
&order_fallback_attr.attr,
+ &cmpxchg_double_fail_attr.attr,
+ &cmpxchg_double_cpu_fail_attr.attr,
#endif
#ifdef CONFIG_FAILSLAB
&failslab_attr.attr,
git.openpandora.org / pandora-kernel.git / commitdiff