Commit 4b6f0750 authored by Christoph Lameter's avatar Christoph Lameter Committed by Linus Torvalds
Browse files

SLUB: Define functions for cpu slab handling instead of using PageActive

Use inline functions to access the per cpu bit.  Intoduce the notion of
"freezing" a slab to make things more understandable.

Signed-off-by: default avatarChristoph Lameter <>
Signed-off-by: default avatarAndrew Morton <>
Signed-off-by: default avatarLinus Torvalds <>
parent 3ca12ee5
......@@ -78,10 +78,18 @@
* Overloading of page flags that are otherwise used for LRU management.
* PageActive The slab is used as a cpu cache. Allocations
* may be performed from the slab. The slab is not
* on any slab list and cannot be moved onto one.
* The cpu slab may be equipped with an additioanl
* PageActive The slab is frozen and exempt from list processing.
* This means that the slab is dedicated to a purpose
* such as satisfying allocations for a specific
* processor. Objects may be freed in the slab while
* it is frozen but slab_free will then skip the usual
* list operations. It is up to the processor holding
* the slab to integrate the slab into the slab lists
* when the slab is no longer needed.
* One use of this flag is to mark slabs that are
* used for allocations. Then such a slab becomes a cpu
* slab. The cpu slab may be equipped with an additional
* lockless_freelist that allows lockless access to
* free objects in addition to the regular freelist
* that requires the slab lock.
......@@ -91,6 +99,21 @@
* the fast path and disables lockless freelists.
static inline int SlabFrozen(struct page *page)
return PageActive(page);
static inline void SetSlabFrozen(struct page *page)
static inline void ClearSlabFrozen(struct page *page)
static inline int SlabDebug(struct page *page)
......@@ -1135,11 +1158,12 @@ static void remove_partial(struct kmem_cache *s,
* Must hold list_lock.
static int lock_and_del_slab(struct kmem_cache_node *n, struct page *page)
static inline int lock_and_freeze_slab(struct kmem_cache_node *n, struct page *page)
if (slab_trylock(page)) {
return 1;
return 0;
......@@ -1163,7 +1187,7 @@ static struct page *get_partial_node(struct kmem_cache_node *n)
list_for_each_entry(page, &n->partial, lru)
if (lock_and_del_slab(n, page))
if (lock_and_freeze_slab(n, page))
goto out;
page = NULL;
......@@ -1242,10 +1266,11 @@ static struct page *get_partial(struct kmem_cache *s, gfp_t flags, int node)
* On exit the slab lock will have been dropped.
static void putback_slab(struct kmem_cache *s, struct page *page)
static void unfreeze_slab(struct kmem_cache *s, struct page *page)
struct kmem_cache_node *n = get_node(s, page_to_nid(page));
if (page->inuse) {
if (page->freelist)
......@@ -1296,9 +1321,7 @@ static void deactivate_slab(struct kmem_cache *s, struct page *page, int cpu)
s->cpu_slab[cpu] = NULL;
putback_slab(s, page);
unfreeze_slab(s, page);
static void flush_slab(struct kmem_cache *s, struct page *page, int cpu)
......@@ -1389,9 +1412,7 @@ another_slab:
page = get_partial(s, gfpflags, node);
if (page) {
s->cpu_slab[cpu] = page;
goto load_freelist;
......@@ -1421,7 +1442,9 @@ have_slab:
flush_slab(s, s->cpu_slab[cpu], cpu);
goto have_slab;
s->cpu_slab[cpu] = page;
goto load_freelist;
return NULL;
......@@ -1508,11 +1531,7 @@ checks_ok:
page->freelist = object;
if (unlikely(PageActive(page)))
* Cpu slabs are never on partial lists and are
* never freed.
if (unlikely(SlabFrozen(page)))
goto out_unlock;
if (unlikely(!page->inuse))
......@@ -1544,7 +1563,7 @@ slab_empty:
if (!free_object_checks(s, page, x))
goto out_unlock;
if (!PageActive(page) && !page->freelist)
if (!SlabFrozen(page) && !page->freelist)
remove_full(s, page);
if (s->flags & SLAB_STORE_USER)
set_track(s, x, TRACK_FREE, addr);
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