Re: [PATCH memcg v4] net: set proper memcg for net_init hooks allocations

[Roman Gushchin]

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@xxxxxxxxxx>
> ---
> 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@xxxxxxxxx>

Thanks!