slub: explicit list_lock taking
The allocator fastpath rework does change the usage of the list_lock.
Remove the list_lock processing from the functions that hide them from the
critical sections and move them into those critical sections.
This in turn simplifies the support functions (no __ variant needed anymore)
and simplifies the lock handling on bootstrap.
Inline add_partial since it becomes pretty simple.
Signed-off-by: Christoph Lameter <cl@linux.com>
Signed-off-by: Pekka Enberg <penberg@kernel.org>
diff --git a/mm/slub.c b/mm/slub.c
index be6715d..e39be09 100644
--- a/mm/slub.c
+++ b/mm/slub.c
@@ -916,26 +916,27 @@
/*
* 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);
- list_add(&page->lru, &n->full);
- spin_unlock(&n->list_lock);
-}
-
-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));
+ list_add(&page->lru, &n->full);
+}
- spin_lock(&n->list_lock);
+/*
+ * list_lock must be held.
+ */
+static void remove_full(struct kmem_cache *s, struct page *page)
+{
+ if (!(s->flags & SLAB_STORE_USER))
+ return;
+
list_del(&page->lru);
- spin_unlock(&n->list_lock);
}
/* Tracking of the number of slabs for debugging purposes */
@@ -1060,8 +1061,13 @@
}
/* Special debug activities for freeing objects */
- if (!page->frozen && !page->freelist)
+ if (!page->frozen && !page->freelist) {
+ struct kmem_cache_node *n = get_node(s, page_to_nid(page));
+
+ spin_lock(&n->list_lock);
remove_full(s, page);
+ spin_unlock(&n->list_lock);
+ }
if (s->flags & SLAB_STORE_USER)
set_track(s, object, TRACK_FREE, addr);
trace(s, page, object, 0);
@@ -1170,7 +1176,8 @@
{ 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 unsigned long kmem_cache_flags(unsigned long objsize,
unsigned long flags, const char *name,
void (*ctor)(void *))
@@ -1420,38 +1427,33 @@
}
/*
- * 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.
*/
@@ -1459,7 +1461,7 @@
struct page *page)
{
if (slab_trylock(page)) {
- __remove_partial(n, page);
+ remove_partial(n, page);
return 1;
}
return 0;
@@ -1576,12 +1578,17 @@
if (page->inuse) {
if (page->freelist) {
+ spin_lock(&n->list_lock);
add_partial(n, page, tail);
+ spin_unlock(&n->list_lock);
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);
+ if (kmem_cache_debug(s) && (s->flags & SLAB_STORE_USER)) {
+ spin_lock(&n->list_lock);
+ add_full(s, n, page);
+ spin_unlock(&n->list_lock);
+ }
}
slab_unlock(page);
} else {
@@ -1597,7 +1604,9 @@
* kmem_cache_shrink can reclaim any empty slabs from
* the partial list.
*/
+ spin_lock(&n->list_lock);
add_partial(n, page, 1);
+ spin_unlock(&n->list_lock);
slab_unlock(page);
} else {
slab_unlock(page);
@@ -2099,7 +2108,11 @@
* then add it.
*/
if (unlikely(!prior)) {
+ struct kmem_cache_node *n = get_node(s, page_to_nid(page));
+
+ spin_lock(&n->list_lock);
add_partial(get_node(s, page_to_nid(page)), page, 1);
+ spin_unlock(&n->list_lock);
stat(s, FREE_ADD_PARTIAL);
}
@@ -2113,7 +2126,11 @@
/*
* Slab still on the partial list.
*/
- remove_partial(s, 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);
stat(s, FREE_REMOVE_PARTIAL);
}
slab_unlock(page);
@@ -2391,7 +2408,6 @@
{
struct page *page;
struct kmem_cache_node *n;
- unsigned long flags;
BUG_ON(kmem_cache_node->size < sizeof(struct kmem_cache_node));
@@ -2418,14 +2434,7 @@
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)
@@ -2709,7 +2718,7 @@
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,
@@ -3047,7 +3056,7 @@
* may have freed the last object and be
* waiting to release the slab.
*/
- __remove_partial(n, page);
+ remove_partial(n, page);
slab_unlock(page);
discard_slab(s, page);
} else {