Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932259Ab2J2Ku7 (ORCPT ); Mon, 29 Oct 2012 06:50:59 -0400 Received: from mailhub.sw.ru ([195.214.232.25]:32295 "EHLO relay.sw.ru" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755738Ab2J2Ku5 (ORCPT ); Mon, 29 Oct 2012 06:50:57 -0400 From: Glauber Costa To: Cc: , Glauber Costa , Christoph Lameter , Pekka Enberg , David Rientjes , JoonSoo Kim Subject: [PATCH] slab: annotate on-slab caches nodelist locks Date: Mon, 29 Oct 2012 14:49:39 +0400 Message-Id: <1351507779-26847-1-git-send-email-glommer@parallels.com> X-Mailer: git-send-email 1.7.11.7 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 3195 Lines: 100 We currently provide lockdep annotation for kmalloc caches, and also caches that have SLAB_DEBUG_OBJECTS enabled. The reason for this is that we can quite frequently nest in the l3->list_lock lock, which is not something trivial to avoid. My proposal with this patch, is to extend this to caches whose slab management object lives within the slab as well ("on_slab"). The need for this arose in the context of testing kmemcg-slab patches. With such patchset, we can have per-memcg kmalloc caches. So the same path that led to nesting between kmalloc caches will could then lead to in-memcg nesting. Because they are not annotated, lockdep will trigger. Signed-off-by: Glauber Costa CC: Christoph Lameter CC: Pekka Enberg CC: David Rientjes CC: JoonSoo Kim --- Instead of "on_slab", I considered checking the memcg cache's root cache, and annotating that only in case this is a kmalloc cache. I ended up annotating on_slab caches, because given how frequently those locks can nest, it seemed like a safe choice to go. I was a little bit inspired by the key's name as well, that indicated this could work for all on_slab caches. Let me know if you guys want a different test condition for this. --- mm/slab.c | 30 +++++++++++++++++++++++++++++- 1 file changed, 29 insertions(+), 1 deletion(-) diff --git a/mm/slab.c b/mm/slab.c index 9b7f6b63..ef1c8b3 100644 --- a/mm/slab.c +++ b/mm/slab.c @@ -654,6 +654,26 @@ static void init_node_lock_keys(int q) } } +static void on_slab_lock_classes_node(struct kmem_cache *cachep, int q) +{ + struct kmem_list3 *l3; + l3 = cachep->nodelists[q]; + if (!l3) + return; + + slab_set_lock_classes(cachep, &on_slab_l3_key, + &on_slab_alc_key, q); +} + +static inline void on_slab_lock_classes(struct kmem_cache *cachep) +{ + int node; + + VM_BUG_ON(OFF_SLAB(cachep)); + for_each_node(node) + on_slab_lock_classes_node(cachep, node); +} + static inline void init_lock_keys(void) { int node; @@ -670,6 +690,10 @@ static inline void init_lock_keys(void) { } +static inline void on_slab_lock_classes(struct kmem_cache *cachep) +{ +} + static void slab_set_debugobj_lock_classes_node(struct kmem_cache *cachep, int node) { } @@ -1397,6 +1421,9 @@ static int __cpuinit cpuup_prepare(long cpu) free_alien_cache(alien); if (cachep->flags & SLAB_DEBUG_OBJECTS) slab_set_debugobj_lock_classes_node(cachep, node); + else if (!OFF_SLAB(cachep) && + !(cachep->flags & SLAB_DESTROY_BY_RCU)) + on_slab_lock_classes_node(cachep, node); } init_node_lock_keys(node); @@ -2554,7 +2581,8 @@ __kmem_cache_create (struct kmem_cache *cachep, unsigned long flags) WARN_ON_ONCE(flags & SLAB_DESTROY_BY_RCU); slab_set_debugobj_lock_classes(cachep); - } + } else if (!OFF_SLAB(cachep) && !(flags & SLAB_DESTROY_BY_RCU)) + on_slab_lock_classes(cachep); return 0; } -- 1.7.11.7 -- 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/