Re: [PATCH bpf-next 0/5] bpf, mm: introduce cgroup.memory=nobpf

[Roman Gushchin <roman.gushchin@linux.dev>]

On Sun, Feb 05, 2023 at 06:58:00AM +0000, Yafang Shao wrote:
> The bpf memory accouting has some known problems in contianer
> environment,
> 
> - The container memory usage is not consistent if there's pinned bpf
>   program
>   After the container restart, the leftover bpf programs won't account
>   to the new generation, so the memory usage of the container is not
>   consistent. This issue can be resolved by introducing selectable
>   memcg, but we don't have an agreement on the solution yet. See also
>   the discussions at https://lwn.net/Articles/905150/ .
> 
> - The leftover non-preallocated bpf map can't be limited
>   The leftover bpf map will be reparented, and thus it will be limited by 
>   the parent, rather than the container itself. Furthermore, if the
>   parent is destroyed, it be will limited by its parent's parent, and so
>   on. It can also be resolved by introducing selectable memcg.
> 
> - The memory dynamically allocated in bpf prog is charged into root memcg
>   only
>   Nowdays the bpf prog can dynamically allocate memory, for example via
>   bpf_obj_new(), but it only allocate from the global bpf_mem_alloc
>   pool, so it will charge into root memcg only. That needs to be
>   addressed by a new proposal.
> 
> So let's give the user an option to disable bpf memory accouting.
> 
> The idea of "cgroup.memory=nobpf" is originally by Tejun[1].
> 
> [1]. https://lwn.net/ml/linux-mm/YxjOawzlgE458ezL@slm.duckdns.org/
> 
> Yafang Shao (5):
>   mm: memcontrol: add new kernel parameter cgroup.memory=nobpf
>   bpf: use bpf_map_kvcalloc in bpf_local_storage
>   bpf: introduce bpf_memcg_flags()
>   bpf: allow to disable bpf map memory accounting
>   bpf: allow to disable bpf prog memory accounting

Hello Yafang!

Overall the patch looks good to me, please, feel free to add
Acked-by: Roman Gushchin <roman.gushchin@linux.dev>

I'd squash patch (3) into (4), but up to you.

Thanks!