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Date:   Tue, 26 Apr 2022 15:13:13 -0700
From:   Roman Gushchin <roman.gushchin@linux.dev>
To:     Vasily Averin <vvs@openvz.org>
Cc:     Vlastimil Babka <vbabka@suse.cz>,
        Shakeel Butt <shakeelb@google.com>, kernel@openvz.org,
        Florian Westphal <fw@strlen.de>, linux-kernel@vger.kernel.org,
        Michal Hocko <mhocko@suse.com>, cgroups@vger.kernel.org,
        netdev@vger.kernel.org, "David S. Miller" <davem@davemloft.net>,
        Jakub Kicinski <kuba@kernel.org>,
        Paolo Abeni <pabeni@redhat.com>
Subject: Re: [PATCH memcg v4] net: set proper memcg for net_init hooks
 allocations
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References: <YmdeCqi6wmgiSiWh@carbon>
 <33085523-a8b9-1bf6-2726-f456f59015ef@openvz.org>
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On Tue, Apr 26, 2022 at 09:43:43AM +0300, Vasily Averin wrote:
> __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_ACCOUNT marked
> allocation are accounted for corresponding container/memcg.
> 
> 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 <vvs@openvz.org>
> ---
> v4: get_mem_cgroup_from_kmem() renamed to get_mem_cgroup_from_obj(),
>     get_net_memcg() replaced by mem_cgroup_or_root(), suggested by Roman.
> 
> 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 | 27 ++++++++++++++++++++++++++-
>  net/core/net_namespace.c   |  7 +++++++
>  2 files changed, 33 insertions(+), 1 deletion(-)

Acked-by: Roman Gushchin <roman.gushchin@linux.dev>

Thanks!