Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752925AbaACSB4 (ORCPT ); Fri, 3 Jan 2014 13:01:56 -0500 Received: from mga02.intel.com ([134.134.136.20]:42439 "EHLO mga02.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751125AbaACSBz (ORCPT ); Fri, 3 Jan 2014 13:01:55 -0500 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="4.95,599,1384329600"; d="scan'208";a="433584698" Subject: [PATCH 1/9] mm: slab/slub: use page->list consistently instead of page->lru To: linux-mm@kvack.org Cc: linux-kernel@vger.kernel.org, akpm@linux-foundation.org, penberg@kernel.org, cl@linux-foundation.org, Dave Hansen From: Dave Hansen Date: Fri, 03 Jan 2014 10:01:48 -0800 References: <20140103180147.6566F7C1@viggo.jf.intel.com> In-Reply-To: <20140103180147.6566F7C1@viggo.jf.intel.com> Message-Id: <20140103180148.A61B8590@viggo.jf.intel.com> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 8032 Lines: 246 From: Dave Hansen 'struct page' has two list_head fields: 'lru' and 'list'. Conveniently, they are unioned together. This means that code can use them interchangably, which gets horribly confusing like with this nugget from slab.c: > list_del(&page->lru); > if (page->active == cachep->num) > list_add(&page->list, &n->slabs_full); This patch makes the slab and slub code use page->list universally instead of mixing ->list and ->lru. It also adds some comments to attempt to keep new users from picking up uses of ->list. So, the new rule is: page->list is what the slabs use. page->lru is for everybody else. This is a pretty arbitrary rule, but we need _something_. Maybe we should just axe the ->list one and make the sl?bs use ->lru. Signed-off-by: Dave Hansen --- linux.git-davehans/include/linux/mm_types.h | 5 ++ linux.git-davehans/mm/slab.c | 50 ++++++++++++++-------------- 2 files changed, 29 insertions(+), 26 deletions(-) diff -puN include/linux/mm_types.h~make-slab-use-page-lru-vs-list-consistently include/linux/mm_types.h --- linux.git/include/linux/mm_types.h~make-slab-use-page-lru-vs-list-consistently 2014-01-02 13:40:29.087256768 -0800 +++ linux.git-davehans/include/linux/mm_types.h 2014-01-02 13:40:29.093257038 -0800 @@ -124,6 +124,8 @@ struct page { union { struct list_head lru; /* Pageout list, eg. active_list * protected by zone->lru_lock ! + * Can be used as a generic list + * by the page owner. */ struct { /* slub per cpu partial pages */ struct page *next; /* Next partial slab */ @@ -136,7 +138,8 @@ struct page { #endif }; - struct list_head list; /* slobs list of pages */ + struct list_head list; /* sl[aou]bs list of pages. + * do not use outside of slabs */ struct slab *slab_page; /* slab fields */ struct rcu_head rcu_head; /* Used by SLAB * when destroying via RCU diff -puN mm/slab.c~make-slab-use-page-lru-vs-list-consistently mm/slab.c --- linux.git/mm/slab.c~make-slab-use-page-lru-vs-list-consistently 2014-01-02 13:40:29.090256903 -0800 +++ linux.git-davehans/mm/slab.c 2014-01-02 13:40:29.095257128 -0800 @@ -765,15 +765,15 @@ static void recheck_pfmemalloc_active(st return; spin_lock_irqsave(&n->list_lock, flags); - list_for_each_entry(page, &n->slabs_full, lru) + list_for_each_entry(page, &n->slabs_full, list) if (is_slab_pfmemalloc(page)) goto out; - list_for_each_entry(page, &n->slabs_partial, lru) + list_for_each_entry(page, &n->slabs_partial, list) if (is_slab_pfmemalloc(page)) goto out; - list_for_each_entry(page, &n->slabs_free, lru) + list_for_each_entry(page, &n->slabs_free, list) if (is_slab_pfmemalloc(page)) goto out; @@ -1428,7 +1428,7 @@ void __init kmem_cache_init(void) { int i; - BUILD_BUG_ON(sizeof(((struct page *)NULL)->lru) < + BUILD_BUG_ON(sizeof(((struct page *)NULL)->list) < sizeof(struct rcu_head)); kmem_cache = &kmem_cache_boot; setup_node_pointer(kmem_cache); @@ -1624,15 +1624,15 @@ slab_out_of_memory(struct kmem_cache *ca continue; spin_lock_irqsave(&n->list_lock, flags); - list_for_each_entry(page, &n->slabs_full, lru) { + list_for_each_entry(page, &n->slabs_full, list) { active_objs += cachep->num; active_slabs++; } - list_for_each_entry(page, &n->slabs_partial, lru) { + list_for_each_entry(page, &n->slabs_partial, list) { active_objs += page->active; active_slabs++; } - list_for_each_entry(page, &n->slabs_free, lru) + list_for_each_entry(page, &n->slabs_free, list) num_slabs++; free_objects += n->free_objects; @@ -2424,11 +2424,11 @@ static int drain_freelist(struct kmem_ca goto out; } - page = list_entry(p, struct page, lru); + page = list_entry(p, struct page, list); #if DEBUG BUG_ON(page->active); #endif - list_del(&page->lru); + list_del(&page->list); /* * Safe to drop the lock. The slab is no longer linked * to the cache. @@ -2721,7 +2721,7 @@ static int cache_grow(struct kmem_cache spin_lock(&n->list_lock); /* Make slab active. */ - list_add_tail(&page->lru, &(n->slabs_free)); + list_add_tail(&page->list, &(n->slabs_free)); STATS_INC_GROWN(cachep); n->free_objects += cachep->num; spin_unlock(&n->list_lock); @@ -2864,7 +2864,7 @@ retry: goto must_grow; } - page = list_entry(entry, struct page, lru); + page = list_entry(entry, struct page, list); check_spinlock_acquired(cachep); /* @@ -2884,7 +2884,7 @@ retry: } /* move slabp to correct slabp list: */ - list_del(&page->lru); + list_del(&page->list); if (page->active == cachep->num) list_add(&page->list, &n->slabs_full); else @@ -3163,7 +3163,7 @@ retry: goto must_grow; } - page = list_entry(entry, struct page, lru); + page = list_entry(entry, struct page, list); check_spinlock_acquired_node(cachep, nodeid); STATS_INC_NODEALLOCS(cachep); @@ -3175,12 +3175,12 @@ retry: obj = slab_get_obj(cachep, page, nodeid); n->free_objects--; /* move slabp to correct slabp list: */ - list_del(&page->lru); + list_del(&page->list); if (page->active == cachep->num) - list_add(&page->lru, &n->slabs_full); + list_add(&page->list, &n->slabs_full); else - list_add(&page->lru, &n->slabs_partial); + list_add(&page->list, &n->slabs_partial); spin_unlock(&n->list_lock); goto done; @@ -3337,7 +3337,7 @@ static void free_block(struct kmem_cache page = virt_to_head_page(objp); n = cachep->node[node]; - list_del(&page->lru); + list_del(&page->list); check_spinlock_acquired_node(cachep, node); slab_put_obj(cachep, page, objp, node); STATS_DEC_ACTIVE(cachep); @@ -3355,14 +3355,14 @@ static void free_block(struct kmem_cache */ slab_destroy(cachep, page); } else { - list_add(&page->lru, &n->slabs_free); + list_add(&page->list, &n->slabs_free); } } else { /* Unconditionally move a slab to the end of the * partial list on free - maximum time for the * other objects to be freed, too. */ - list_add_tail(&page->lru, &n->slabs_partial); + list_add_tail(&page->list, &n->slabs_partial); } } } @@ -3404,7 +3404,7 @@ free_done: while (p != &(n->slabs_free)) { struct page *page; - page = list_entry(p, struct page, lru); + page = list_entry(p, struct page, list); BUG_ON(page->active); i++; @@ -4029,13 +4029,13 @@ void get_slabinfo(struct kmem_cache *cac check_irq_on(); spin_lock_irq(&n->list_lock); - list_for_each_entry(page, &n->slabs_full, lru) { + list_for_each_entry(page, &n->slabs_full, list) { if (page->active != cachep->num && !error) error = "slabs_full accounting error"; active_objs += cachep->num; active_slabs++; } - list_for_each_entry(page, &n->slabs_partial, lru) { + list_for_each_entry(page, &n->slabs_partial, list) { if (page->active == cachep->num && !error) error = "slabs_partial accounting error"; if (!page->active && !error) @@ -4043,7 +4043,7 @@ void get_slabinfo(struct kmem_cache *cac active_objs += page->active; active_slabs++; } - list_for_each_entry(page, &n->slabs_free, lru) { + list_for_each_entry(page, &n->slabs_free, list) { if (page->active && !error) error = "slabs_free accounting error"; num_slabs++; @@ -4266,9 +4266,9 @@ static int leaks_show(struct seq_file *m check_irq_on(); spin_lock_irq(&n->list_lock); - list_for_each_entry(page, &n->slabs_full, lru) + list_for_each_entry(page, &n->slabs_full, list) handle_slab(x, cachep, page); - list_for_each_entry(page, &n->slabs_partial, lru) + list_for_each_entry(page, &n->slabs_partial, list) handle_slab(x, cachep, page); spin_unlock_irq(&n->list_lock); } _ -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/