Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932934AbbFCMgm (ORCPT ); Wed, 3 Jun 2015 08:36:42 -0400 Received: from mail.linuxfoundation.org ([140.211.169.12]:58405 "EHLO mail.linuxfoundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756283AbbFCMVE (ORCPT ); Wed, 3 Jun 2015 08:21:04 -0400 From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Vladimir Davydov , Tejun Heo , Johannes Weiner , Michal Hocko , Christoph Lameter , Pekka Enberg , David Rientjes , Joonsoo Kim , Greg Thelen , Andrew Morton , Linus Torvalds Subject: [PATCH 4.0 111/148] kernfs: do not account ino_ida allocations to memcg Date: Wed, 3 Jun 2015 21:09:41 +0900 Message-Id: <20150603114210.208305815@linuxfoundation.org> X-Mailer: git-send-email 2.4.2 In-Reply-To: <20150603114205.337615117@linuxfoundation.org> References: <20150603114205.337615117@linuxfoundation.org> User-Agent: quilt/0.64 MIME-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-15 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2722 Lines: 68 4.0-stable review patch. If anyone has any objections, please let me know. ------------------ From: Vladimir Davydov commit 499611ed451508a42d1d7d1faff10177827755d5 upstream. root->ino_ida is used for kernfs inode number allocations. Since IDA has a layered structure, different IDs can reside on the same layer, which is currently accounted to some memory cgroup. The problem is that each kmem cache of a memory cgroup has its own directory on sysfs (under /sys/fs/kernel//cgroup). If the inode number of such a directory or any file in it gets allocated from a layer accounted to the cgroup which the cache is created for, the cgroup will get pinned for good, because one has to free all kmem allocations accounted to a cgroup in order to release it and destroy all its kmem caches. That said we must not account layers of ino_ida to any memory cgroup. Since per net init operations may create new sysfs entries directly (e.g. lo device) or indirectly (nf_conntrack creates a new kmem cache per each namespace, which, in turn, creates new sysfs entries), an easy way to reproduce this issue is by creating network namespace(s) from inside a kmem-active memory cgroup. Signed-off-by: Vladimir Davydov Acked-by: Tejun Heo Cc: Johannes Weiner Cc: Michal Hocko Cc: Christoph Lameter Cc: Pekka Enberg Cc: David Rientjes Cc: Joonsoo Kim Cc: Greg Thelen Cc: Greg Kroah-Hartman Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds Signed-off-by: Greg Kroah-Hartman --- fs/kernfs/dir.c | 9 ++++++++- 1 file changed, 8 insertions(+), 1 deletion(-) --- a/fs/kernfs/dir.c +++ b/fs/kernfs/dir.c @@ -518,7 +518,14 @@ static struct kernfs_node *__kernfs_new_ if (!kn) goto err_out1; - ret = ida_simple_get(&root->ino_ida, 1, 0, GFP_KERNEL); + /* + * If the ino of the sysfs entry created for a kmem cache gets + * allocated from an ida layer, which is accounted to the memcg that + * owns the cache, the memcg will get pinned forever. So do not account + * ino ida allocations. + */ + ret = ida_simple_get(&root->ino_ida, 1, 0, + GFP_KERNEL | __GFP_NOACCOUNT); if (ret < 0) goto err_out2; kn->ino = ret; -- 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/