From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-pf0-f176.google.com (mail-pf0-f176.google.com [209.85.192.176]) by kanga.kvack.org (Postfix) with ESMTP id 341824403D8 for ; Fri, 5 Feb 2016 10:44:49 -0500 (EST) Received: by mail-pf0-f176.google.com with SMTP id n128so70100670pfn.3 for ; Fri, 05 Feb 2016 07:44:49 -0800 (PST) Received: from mx2.parallels.com (mx2.parallels.com. [199.115.105.18]) by mx.google.com with ESMTPS id b10si24662214pas.7.2016.02.05.07.44.48 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Fri, 05 Feb 2016 07:44:48 -0800 (PST) Subject: Re: [PATCHv5] mm: slab: free kmem_cache_node after destroy sysfs file References: <1454686692-18939-1-git-send-email-dsafonov@virtuozzo.com> From: Dmitry Safonov Message-ID: <56B4C369.3090709@virtuozzo.com> Date: Fri, 5 Feb 2016 18:44:41 +0300 MIME-Version: 1.0 In-Reply-To: <1454686692-18939-1-git-send-email-dsafonov@virtuozzo.com> Content-Type: text/plain; charset="windows-1252"; format=flowed Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org List-ID: To: akpm@linux-foundation.org Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org, 0x7f454c46@gmail.com, Vladimir Davydov , Christoph Lameter , Pekka Enberg , David Rientjes , Joonsoo Kim On 02/05/2016 06:38 PM, Dmitry Safonov wrote: > With enabled slub_debug alloc_calls_show will try to track location and > user of slab object on each online node, kmem_cache_node structure > shouldn't be freed till there is the last reference to sysfs file. Oh, scratch this, friday evening, will resent update just now. > > Fixes the following panic: > [43963.463055] BUG: unable to handle kernel > [43963.463090] NULL pointer dereference at 0000000000000020 > [43963.463146] IP: [] list_locations+0x169/0x4e0 > [43963.463185] PGD 257304067 PUD 438456067 PMD 0 > [43963.463220] Oops: 0000 [#1] SMP > [43963.463850] CPU: 3 PID: 973074 Comm: cat ve: 0 Not tainted 3.10.0-229.7.2.ovz.9.30-00007-japdoll-dirty #2 9.30 > [43963.463913] Hardware name: DEPO Computers To Be Filled By O.E.M./H67DE3, BIOS L1.60c 07/14/2011 > [43963.463976] task: ffff88042a5dc5b0 ti: ffff88037f8d8000 task.ti: ffff88037f8d8000 > [43963.464036] RIP: 0010:[] [] list_locations+0x169/0x4e0 > [43963.464725] Call Trace: > [43963.464756] [] alloc_calls_show+0x1d/0x30 > [43963.464793] [] slab_attr_show+0x1b/0x30 > [43963.464829] [] sysfs_read_file+0x9a/0x1a0 > [43963.464865] [] vfs_read+0x9c/0x170 > [43963.464900] [] SyS_read+0x58/0xb0 > [43963.464936] [] system_call_fastpath+0x16/0x1b > [43963.464970] Code: 5e 07 12 00 b9 00 04 00 00 3d 00 04 00 00 0f 4f c1 3d 00 04 00 00 89 45 b0 0f 84 c3 00 00 00 48 63 45 b0 49 8b 9c c4 f8 00 00 00 <48> 8b 43 20 48 85 c0 74 b6 48 89 df e8 46 37 44 00 48 8b 53 10 > [43963.465119] RIP [] list_locations+0x169/0x4e0 > [43963.465155] RSP > [43963.465185] CR2: 0000000000000020 > > Separated nodes structures freeing into __kmem_cache_free_nodes and use > it at kmem_cache_release. > > Cc: Vladimir Davydov > Cc: Christoph Lameter > Cc: Pekka Enberg > Cc: David Rientjes > Cc: Joonsoo Kim > Signed-off-by: Dmitry Safonov > --- > v2: Down with SLAB_SUPPORTS_SYSFS thing. > v3: Moved sysfs_slab_remove inside shutdown_cache > v4: Reworked all to shutdown & free caches on object->release() > v5: Made separate __kmem_cache_free_nodes function and call it on release. > > mm/slab.c | 12 +++++++++--- > mm/slab.h | 1 + > mm/slab_common.c | 1 + > mm/slob.c | 4 ++++ > mm/slub.c | 8 ++++---- > 5 files changed, 19 insertions(+), 7 deletions(-) > > diff --git a/mm/slab.c b/mm/slab.c > index 6ecc697..3ccdf3c 100644 > --- a/mm/slab.c > +++ b/mm/slab.c > @@ -2276,6 +2276,7 @@ __kmem_cache_create (struct kmem_cache *cachep, unsigned long flags) > err = setup_cpu_cache(cachep, gfp); > if (err) { > __kmem_cache_shutdown(cachep); > + __kmem_cache_free_nodes(cachep); > return err; > } > > @@ -2414,8 +2415,6 @@ int __kmem_cache_shrink(struct kmem_cache *cachep, bool deactivate) > > int __kmem_cache_shutdown(struct kmem_cache *cachep) > { > - int i; > - struct kmem_cache_node *n; > int rc = __kmem_cache_shrink(cachep, false); > > if (rc) > @@ -2423,6 +2422,14 @@ int __kmem_cache_shutdown(struct kmem_cache *cachep) > > free_percpu(cachep->cpu_cache); > > + return 0; > +} > + > +void __kmem_cache_free_nodes(struct kmem_cache *cachep) > +{ > + int i; > + struct kmem_cache_node *n; > + > /* NUMA: free the node structures */ > for_each_kmem_cache_node(cachep, i, n) { > kfree(n->shared); > @@ -2430,7 +2437,6 @@ int __kmem_cache_shutdown(struct kmem_cache *cachep) > kfree(n); > cachep->node[i] = NULL; > } > - return 0; > } > > /* > diff --git a/mm/slab.h b/mm/slab.h > index 834ad24..b1a6576 100644 > --- a/mm/slab.h > +++ b/mm/slab.h > @@ -140,6 +140,7 @@ static inline unsigned long kmem_cache_flags(unsigned long object_size, > #define CACHE_CREATE_MASK (SLAB_CORE_FLAGS | SLAB_DEBUG_FLAGS | SLAB_CACHE_FLAGS) > > int __kmem_cache_shutdown(struct kmem_cache *); > +void __kmem_cache_free_nodes(struct kmem_cache *); > int __kmem_cache_shrink(struct kmem_cache *, bool); > void slab_kmem_cache_release(struct kmem_cache *); > > diff --git a/mm/slab_common.c b/mm/slab_common.c > index b50aef0..0bc2da3 100644 > --- a/mm/slab_common.c > +++ b/mm/slab_common.c > @@ -693,6 +693,7 @@ static inline int shutdown_memcg_caches(struct kmem_cache *s, > > void slab_kmem_cache_release(struct kmem_cache *s) > { > + __kmem_cache_free_nodes(s); > destroy_memcg_params(s); > kfree_const(s->name); > kmem_cache_free(kmem_cache, s); > diff --git a/mm/slob.c b/mm/slob.c > index 17e8f8c..242d77d 100644 > --- a/mm/slob.c > +++ b/mm/slob.c > @@ -630,6 +630,10 @@ int __kmem_cache_shutdown(struct kmem_cache *c) > return 0; > } > > +void __kmem_cache_free_nodes(struct kmem_cache *c) > +{ > +} > + > int __kmem_cache_shrink(struct kmem_cache *d, bool deactivate) > { > return 0; > diff --git a/mm/slub.c b/mm/slub.c > index 2e1355a..d05bcea 100644 > --- a/mm/slub.c > +++ b/mm/slub.c > @@ -3173,7 +3173,7 @@ static void early_kmem_cache_node_alloc(int node) > __add_partial(n, page, DEACTIVATE_TO_HEAD); > } > > -static void free_kmem_cache_nodes(struct kmem_cache *s) > +void __kmem_cache_free_nodes(struct kmem_cache *s) > { > int node; > struct kmem_cache_node *n; > @@ -3199,7 +3199,7 @@ static int init_kmem_cache_nodes(struct kmem_cache *s) > GFP_KERNEL, node); > > if (!n) { > - free_kmem_cache_nodes(s); > + __kmem_cache_free_nodes(s); > return 0; > } > > @@ -3405,7 +3405,7 @@ static int kmem_cache_open(struct kmem_cache *s, unsigned long flags) > if (alloc_kmem_cache_cpus(s)) > return 0; > > - free_kmem_cache_nodes(s); > + __kmem_cache_free_nodes(s); > error: > if (flags & SLAB_PANIC) > panic("Cannot create slab %s size=%lu realsize=%u " > @@ -3477,7 +3477,7 @@ static inline int kmem_cache_close(struct kmem_cache *s) > return 1; > } > free_percpu(s->cpu_slab); > - free_kmem_cache_nodes(s); > + __kmem_cache_free_nodes(s); > return 0; > } > -- Regards, Dmitry Safonov -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. 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