From: Shakeel Butt <shakeel.butt@linux.dev>
To: Roman Gushchin <roman.gushchin@linux.dev>
Cc: bpf@vger.kernel.org, linux-mm@kvack.org,
linux-kernel@vger.kernel.org, JP Kobryn <inwardvessel@gmail.com>,
Alexei Starovoitov <ast@kernel.org>,
Daniel Borkmann <daniel@iogearbox.net>,
Michal Hocko <mhocko@kernel.org>,
Johannes Weiner <hannes@cmpxchg.org>
Subject: Re: [PATCH bpf-next v2 2/7] mm: introduce BPF kfuncs to deal with memcg pointers
Date: Fri, 19 Dec 2025 21:20:48 -0800 [thread overview]
Message-ID: <z77od372jts3d73n77v3o7dk4ro7hizuj2zn235vmbltwjnwfy@zkamyu7gf5jj> (raw)
In-Reply-To: <20251220041250.372179-3-roman.gushchin@linux.dev>
On Fri, Dec 19, 2025 at 08:12:45PM -0800, Roman Gushchin wrote:
> To effectively operate with memory cgroups in BPF there is a need
> to convert css pointers to memcg pointers. A simple container_of
> cast which is used in the kernel code can't be used in BPF because
> from the verifier's point of view that's a out-of-bounds memory access.
>
> Introduce helper get/put kfuncs which can be used to get
> a refcounted memcg pointer from the css pointer:
> - bpf_get_mem_cgroup,
> - bpf_put_mem_cgroup.
>
> bpf_get_mem_cgroup() can take both memcg's css and the corresponding
> cgroup's "self" css. It allows it to be used with the existing cgroup
> iterator which iterates over cgroup tree, not memcg tree.
>
> Signed-off-by: Roman Gushchin <roman.gushchin@linux.dev>
Acked-by: Shakeel Butt <shakeel.butt@linux.dev>
next prev parent reply other threads:[~2025-12-20 5:21 UTC|newest]
Thread overview: 25+ messages / expand[flat|nested] mbox.gz Atom feed top
2025-12-20 4:12 [PATCH bpf-next v2 0/7] mm: bpf kfuncs to access memcg data Roman Gushchin
2025-12-20 4:12 ` [PATCH bpf-next v2 1/7] mm: declare memcg_page_state_output() in memcontrol.h Roman Gushchin
2025-12-20 4:12 ` [PATCH bpf-next v2 2/7] mm: introduce BPF kfuncs to deal with memcg pointers Roman Gushchin
2025-12-20 5:20 ` Shakeel Butt [this message]
2025-12-22 0:39 ` Alexei Starovoitov
2025-12-20 4:12 ` [PATCH bpf-next v2 3/7] mm: introduce bpf_get_root_mem_cgroup() BPF kfunc Roman Gushchin
2025-12-20 5:21 ` Shakeel Butt
2025-12-20 4:12 ` [PATCH bpf-next v2 4/7] mm: introduce BPF kfuncs to access memcg statistics and events Roman Gushchin
2025-12-20 4:29 ` bot+bpf-ci
2025-12-20 4:39 ` Roman Gushchin
2025-12-20 5:22 ` Shakeel Butt
2025-12-20 4:12 ` [PATCH bpf-next v2 5/7] mm: introduce BPF kfunc to access memory events Roman Gushchin
2025-12-20 4:29 ` bot+bpf-ci
2025-12-20 4:41 ` Roman Gushchin
2025-12-20 13:19 ` Chris Mason
2025-12-20 18:43 ` Roman Gushchin
2025-12-20 19:59 ` Chris Mason
2025-12-22 22:23 ` Roman Gushchin
2025-12-23 14:09 ` Chris Mason
2025-12-22 0:49 ` Alexei Starovoitov
2025-12-22 0:51 ` Alexei Starovoitov
2025-12-20 4:12 ` [PATCH bpf-next v2 6/7] bpf: selftests: selftests for memcg stat kfuncs Roman Gushchin
2025-12-20 5:23 ` Shakeel Butt
2025-12-20 4:12 ` [PATCH bpf-next v2 7/7] MAINTAINERS: add an entry for MM BPF extensions Roman Gushchin
2025-12-20 5:26 ` Shakeel Butt
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