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-rw-r--r--include/linux/slub_def.h1
-rw-r--r--mm/slub.c65
2 files changed, 61 insertions, 5 deletions
diff --git a/include/linux/slub_def.h b/include/linux/slub_def.h
index c8668d161dd8..b42715294147 100644
--- a/include/linux/slub_def.h
+++ b/include/linux/slub_def.h
@@ -33,6 +33,7 @@ enum stat_item {
DEACTIVATE_REMOTE_FREES,/* Slab contained remotely freed objects */
ORDER_FALLBACK, /* Number of times fallback was necessary */
CMPXCHG_DOUBLE_CPU_FAIL,/* Failure of this_cpu_cmpxchg_double */
+ CMPXCHG_DOUBLE_FAIL, /* Number of times that cmpxchg double did not match */
NR_SLUB_STAT_ITEMS };
struct kmem_cache_cpu {
diff --git a/mm/slub.c b/mm/slub.c
index 5a2d3d8e0558..be6715dd0ee8 100644
--- a/mm/slub.c
+++ b/mm/slub.c
@@ -131,6 +131,9 @@ static inline int kmem_cache_debug(struct kmem_cache *s)
/* 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.
@@ -170,6 +173,7 @@ static inline int kmem_cache_debug(struct kmem_cache *s)
/* Internal SLUB flags */
#define __OBJECT_POISON 0x80000000UL /* Poison object */
+#define __CMPXCHG_DOUBLE 0x40000000UL /* Use cmpxchg_double */
static int kmem_size = sizeof(struct kmem_cache);
@@ -338,6 +342,37 @@ static inline int oo_objects(struct kmem_cache_order_objects x)
return x.x & OO_MASK;
}
+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
+ {
+ if (page->freelist == freelist_old && page->counters == counters_old) {
+ page->freelist = freelist_new;
+ page->counters = counters_new;
+ return 1;
+ }
+ }
+
+ 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.
@@ -2596,6 +2631,12 @@ static int kmem_cache_open(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.
@@ -4248,8 +4289,10 @@ static ssize_t sanity_checks_store(struct kmem_cache *s,
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);
@@ -4263,8 +4306,10 @@ static ssize_t trace_store(struct kmem_cache *s, const char *buf,
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);
@@ -4281,8 +4326,10 @@ static ssize_t red_zone_store(struct kmem_cache *s,
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;
}
@@ -4300,8 +4347,10 @@ static ssize_t poison_store(struct kmem_cache *s,
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;
}
@@ -4319,8 +4368,10 @@ static ssize_t store_user_store(struct kmem_cache *s,
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;
}
@@ -4493,6 +4544,8 @@ 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(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[] = {
@@ -4550,6 +4603,8 @@ static struct attribute *slab_attrs[] = {
&deactivate_to_tail_attr.attr,
&deactivate_remote_frees_attr.attr,
&order_fallback_attr.attr,
+ &cmpxchg_double_fail_attr.attr,
+ &cmpxchg_double_cpu_fail_attr.attr,
#endif
#ifdef CONFIG_FAILSLAB
&failslab_attr.attr,