From 5cc6eee8a8c1aefe9c86fe7345a2aa1c4ca70dc6 Mon Sep 17 00:00:00 2001 From: Christoph Lameter Date: Wed, 1 Jun 2011 12:25:50 -0500 Subject: 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 Signed-off-by: Pekka Enberg --- mm/slub.c | 89 +++++++++++++++++++++++++++++++++++---------------------------- 1 file changed, 49 insertions(+), 40 deletions(-) (limited to 'mm/slub.c') diff --git a/mm/slub.c b/mm/slub.c index be6715dd0ee8..e39be0928a22 100644 --- a/mm/slub.c +++ b/mm/slub.c @@ -916,26 +916,27 @@ static inline void slab_free_hook(struct kmem_cache *s, void *x) /* * 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 */ @@ -1060,8 +1061,13 @@ static noinline int free_debug_processing(struct kmem_cache *s, } /* 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 @@ static inline int slab_pad_check(struct kmem_cache *s, struct page *page) { 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 @@ static __always_inline int slab_trylock(struct page *page) } /* - * 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 @@ static inline int lock_and_freeze_slab(struct kmem_cache_node *n, struct page *page) { if (slab_trylock(page)) { - __remove_partial(n, page); + remove_partial(n, page); return 1; } return 0; @@ -1576,12 +1578,17 @@ static void unfreeze_slab(struct kmem_cache *s, struct page *page, int tail) 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 @@ static void unfreeze_slab(struct kmem_cache *s, struct page *page, int tail) * 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 @@ static void __slab_free(struct kmem_cache *s, struct page *page, * 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_empty: /* * 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 @@ static void early_kmem_cache_node_alloc(int node) { 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 @@ static void early_kmem_cache_node_alloc(int node) 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 @@ static void free_partial(struct kmem_cache *s, struct kmem_cache_node *n) 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 @@ int kmem_cache_shrink(struct kmem_cache *s) * 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 { -- cgit v1.2.3