From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-la0-f42.google.com (mail-la0-f42.google.com [209.85.215.42]) by kanga.kvack.org (Postfix) with ESMTP id C67CA6B0035 for ; Fri, 31 Jan 2014 01:53:55 -0500 (EST) Received: by mail-la0-f42.google.com with SMTP id hr13so3234362lab.1 for ; Thu, 30 Jan 2014 22:53:54 -0800 (PST) Received: from relay.parallels.com (relay.parallels.com. [195.214.232.42]) by mx.google.com with ESMTPS id e6si4242038lam.144.2014.01.30.22.53.53 for (version=TLSv1.2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Thu, 30 Jan 2014 22:53:53 -0800 (PST) Message-ID: <52EB487B.6040701@parallels.com> Date: Fri, 31 Jan 2014 10:53:47 +0400 From: Vladimir Davydov MIME-Version: 1.0 Subject: Re: [PATCH] memcg: fix mutex not unlocked on memcg_create_kmem_cache fail path References: <1391097693-31401-1-git-send-email-vdavydov@parallels.com> <20140130130129.6f8bd7fd9da55d17a9338443@linux-foundation.org> <20140130132939.96a25a37016a12f9a0093a90@linux-foundation.org> <20140130135002.22ce1c12b7136f75e5985df6@linux-foundation.org> <20140130140902.93d35d866f9ea1c697811f6e@linux-foundation.org> <20140130141538.a9e3977b5e7b76bdcf59a15f@linux-foundation.org> In-Reply-To: Content-Type: text/plain; charset="ISO-8859-1" Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org List-ID: To: David Rientjes Cc: Andrew Morton , mhocko@suse.cz, linux-mm@kvack.org, linux-kernel@vger.kernel.org Hi, David Thank you for taking look at this and adding the missing patch description. WRT your patch, please see the comment inline. On 01/31/2014 02:39 AM, David Rientjes wrote: > On Thu, 30 Jan 2014, Andrew Morton wrote: > >>> It always was. >> eh? kmem_cache_create_memcg()'s kstrdup() will allocate the minimum >> needed amount of memory. >> > Ah, good point. We could this incrementally on my patch: > > diff --git a/mm/memcontrol.c b/mm/memcontrol.c > --- a/mm/memcontrol.c > +++ b/mm/memcontrol.c > @@ -637,6 +637,9 @@ int memcg_limited_groups_array_size; > * better kept as an internal representation in cgroup.c. In any case, the > * cgrp_id space is not getting any smaller, and we don't have to necessarily > * increase ours as well if it increases. > + * > + * Updates to MAX_SIZE should update the space for the memcg name in > + * memcg_create_kmem_cache(). > */ > #define MEMCG_CACHES_MIN_SIZE 4 > #define MEMCG_CACHES_MAX_SIZE MEM_CGROUP_ID_MAX > @@ -3400,8 +3403,10 @@ void mem_cgroup_destroy_cache(struct kmem_cache *cachep) > static struct kmem_cache *memcg_create_kmem_cache(struct mem_cgroup *memcg, > struct kmem_cache *s) > { > - char *name = NULL; > struct kmem_cache *new; > + const char *cgrp_name; > + char *name = NULL; > + size_t len; > > BUG_ON(!memcg_can_account_kmem(memcg)); > > @@ -3409,9 +3414,22 @@ static struct kmem_cache *memcg_create_kmem_cache(struct mem_cgroup *memcg, > if (unlikely(!name)) > return NULL; > > + /* > + * Format of a memcg's kmem cache name: > + * (:) > + */ > + len = strlen(s->name); > + /* Space for parentheses, colon, terminator */ > + len += 4; > + /* MEMCG_CACHES_MAX_SIZE is USHRT_MAX */ > + len += 5; > + BUILD_BUG_ON(MEMCG_CACHES_MAX_SIZE > USHRT_MAX); > + This looks cumbersome, IMO. Let's leave it as is for now. AFAIK, cgroup_name() will be reworked soon so that it won't require RCU-context (https://lkml.org/lkml/2014/1/28/530). Therefore, it will be possible to get rid of this pointless tmp_name allocation by making kmem_cache_create_memcg() take not just name, but printf-like format + vargs. Thanks. -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org