From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 37C9DC433F5 for ; Tue, 26 Apr 2022 02:51:01 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S242646AbiDZCyE (ORCPT ); Mon, 25 Apr 2022 22:54:04 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:39372 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230491AbiDZCyE (ORCPT ); Mon, 25 Apr 2022 22:54:04 -0400 Received: from out0.migadu.com (out0.migadu.com [IPv6:2001:41d0:2:267::]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 356A910FD6; Mon, 25 Apr 2022 19:50:58 -0700 (PDT) Date: Mon, 25 Apr 2022 19:50:50 -0700 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux.dev; s=key1; t=1650941456; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=GXBsNESQZfIaAKadUYOa+SDoc+85t8RLisih8+qEL90=; b=BZEJVGSQbQna5YPVt/zgZb1xcavzGypztWiz7oSNbvFlNBt5UIGE3dm8UcDmm+ONRC98Zj tHzuasQXAuszKFYJ/KRekAxhj5LA/p6kbS+3o1nWoqjCepWBpyZavGJuUW3nqOhABMOI7v Dq9s7knx7Mfj6cTS9Z3wqQuxF5PHLDA= X-Report-Abuse: Please report any abuse attempt to abuse@migadu.com and include these headers. From: Roman Gushchin To: Vasily Averin Cc: Vlastimil Babka , Shakeel Butt , kernel@openvz.org, Florian Westphal , linux-kernel@vger.kernel.org, Michal Hocko , cgroups@vger.kernel.org, netdev@vger.kernel.org, "David S. Miller" , Jakub Kicinski , Paolo Abeni Subject: Re: [PATCH memcg v3] net: set proper memcg for net_init hooks allocations Message-ID: References: <20220424144627.GB13403@xsang-OptiPlex-9020> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: X-Migadu-Flow: FLOW_OUT X-Migadu-Auth-User: linux.dev Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org On Mon, Apr 25, 2022 at 01:56:02PM +0300, Vasily Averin wrote: Hello, Vasily! > __register_pernet_operations() executes init hook of registered > pernet_operation structure in all existing net namespaces. > > Typically, these hooks are called by a process associated with > the specified net namespace, and all __GFP_ACCOUNTING marked > allocation are accounted for corresponding container/memcg. __GFP_ACCOUNT > > However __register_pernet_operations() calls the hooks in the same > context, and as a result all marked allocations are accounted > to one memcg for all processed net namespaces. > > This patch adjusts active memcg for each net namespace and helps > to account memory allocated inside ops_init() into the proper memcg. > > Signed-off-by: Vasily Averin > --- > v3: put_net_memcg() replaced by an alreay existing mem_cgroup_put() > It checks memcg before accessing it, this is required for > __register_pernet_operations() called before memcg initialization. > Additionally fixed leading whitespaces in non-memcg_kmem version > of mem_cgroup_from_obj(). > > v2: introduced get/put_net_memcg(), > new functions are moved under CONFIG_MEMCG_KMEM > to fix compilation issues reported by Intel's kernel test robot > > v1: introduced get_mem_cgroup_from_kmem(), which takes the refcount > for the found memcg, suggested by Shakeel > --- > include/linux/memcontrol.h | 29 ++++++++++++++++++++++++++++- > net/core/net_namespace.c | 7 +++++++ > 2 files changed, 35 insertions(+), 1 deletion(-) > > diff --git a/include/linux/memcontrol.h b/include/linux/memcontrol.h > index 0abbd685703b..cfb68a3f7015 100644 > --- a/include/linux/memcontrol.h > +++ b/include/linux/memcontrol.h > @@ -1714,6 +1714,29 @@ static inline int memcg_cache_id(struct mem_cgroup *memcg) > > struct mem_cgroup *mem_cgroup_from_obj(void *p); > > +static inline struct mem_cgroup *get_mem_cgroup_from_kmem(void *p) > +{ > + struct mem_cgroup *memcg; > + > + rcu_read_lock(); > + do { > + memcg = mem_cgroup_from_obj(p); > + } while (memcg && !css_tryget(&memcg->css)); > + rcu_read_unlock(); > + return memcg; > +} Please, rename it to get_mem_cgroup_from_obj() for consistency. > + > +static inline struct mem_cgroup *get_net_memcg(void *p) > +{ > + struct mem_cgroup *memcg; > + > + memcg = get_mem_cgroup_from_kmem(p); > + > + if (!memcg) > + memcg = root_mem_cgroup; > + > + return memcg; > +} I'm not a fan of this helper: it has nothing to do with the networking, actually it's a wrapper of get_mem_cgroup_from_kmem() replacing NULL with root_mem_cgroup. Overall the handling of root_mem_cgroup is very messy, I don't blame this patch. But I wonder if it's better to simple move this code to the call site without introducing a new function? Alternatively, you can introduce something like: struct mem_cgroup *mem_cgroup_or_root(struct mem_cgroup *memcg) { return memcg ? memcg : root_mem_cgroup; } > #else > static inline bool mem_cgroup_kmem_disabled(void) > { > @@ -1763,9 +1786,13 @@ static inline void memcg_put_cache_ids(void) > > static inline struct mem_cgroup *mem_cgroup_from_obj(void *p) > { > - return NULL; > + return NULL; > } > > +static inline struct mem_cgroup *get_net_memcg(void *p) > +{ > + return NULL; > +} > #endif /* CONFIG_MEMCG_KMEM */ > > #endif /* _LINUX_MEMCONTROL_H */ > diff --git a/net/core/net_namespace.c b/net/core/net_namespace.c > index a5b5bb99c644..3093b4d5b2b9 100644 > --- a/net/core/net_namespace.c > +++ b/net/core/net_namespace.c > @@ -26,6 +26,7 @@ > #include > #include > > +#include > /* > * Our network namespace constructor/destructor lists > */ > @@ -1147,7 +1148,13 @@ static int __register_pernet_operations(struct list_head *list, > * setup_net() and cleanup_net() are not possible. > */ > for_each_net(net) { > + struct mem_cgroup *old, *memcg; > + > + memcg = get_net_memcg(net); > + old = set_active_memcg(memcg); > error = ops_init(ops, net); > + set_active_memcg(old); > + mem_cgroup_put(memcg); > if (error) > goto out_undo; > list_add_tail(&net->exit_list, &net_exit_list); > -- > 2.31.1 >