From mboxrd@z Thu Jan  1 00:00:00 1970
From: Roman Gushchin <roman.gushchin-fxUVXftIFDnyG1zEObXtfA@public.gmane.org>
Subject: Re: [PATCH memcg v4] net: set proper memcg for net_init hooks
 allocations
Date: Tue, 26 Apr 2022 15:13:13 -0700
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To: Vasily Averin <vvs-GEFAQzZX7r8dnm+yROfE0A@public.gmane.org>
Cc: Vlastimil Babka <vbabka-AlSwsSmVLrQ@public.gmane.org>, Shakeel Butt <shakeelb-hpIqsD4AKlfQT0dZR+AlfA@public.gmane.org>, kernel-GEFAQzZX7r8dnm+yROfE0A@public.gmane.org, Florian Westphal <fw-HFFVJYpyMKqzQB+pC5nmwQ@public.gmane.org>, linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, Michal Hocko <mhocko-IBi9RG/b67k@public.gmane.org>, cgroups-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, netdev-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, "David S. Miller" <davem-fT/PcQaiUtIeIZ0/mPfg9Q@public.gmane.org>, Jakub Kicinski <kuba-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org>, Paolo Abeni <pabeni-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>

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-GEFAQzZX7r8dnm+yROfE0A@public.gmane.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-fxUVXftIFDnyG1zEObXtfA@public.gmane.org>

Thanks!