From: Shakeel Butt <shakeelb@google.com>
To: Yafang Shao <laoar.shao@gmail.com>
Cc: Alexei Starovoitov <ast@kernel.org>,
Daniel Borkmann <daniel@iogearbox.net>,
Andrii Nakryiko <andrii@kernel.org>, Martin Lau <kafai@fb.com>,
Song Liu <songliubraving@fb.com>, Yonghong Song <yhs@fb.com>,
john fastabend <john.fastabend@gmail.com>,
KP Singh <kpsingh@kernel.org>,
Stanislav Fomichev <sdf@google.com>, Hao Luo <haoluo@google.com>,
jolsa@kernel.org, Johannes Weiner <hannes@cmpxchg.org>,
Michal Hocko <mhocko@kernel.org>,
Roman Gushchin <roman.gushchin@linux.dev>,
Muchun Song <songmuchun@bytedance.com>,
Andrew Morton <akpm@linux-foundation.org>,
netdev <netdev@vger.kernel.org>, bpf <bpf@vger.kernel.org>,
Linux MM <linux-mm@kvack.org>
Subject: Re: [PATCH bpf-next 05/15] bpf: Fix incorrect mem_cgroup_put
Date: Thu, 11 Aug 2022 15:47:31 +0000 [thread overview]
Message-ID: <20220811154731.3smhom6v4qy2u6rd@google.com> (raw)
In-Reply-To: <CALOAHbBk+komswLqs0KBg8FeFAYpC20HjXrUeZA-=7cWf6nRUw@mail.gmail.com>
On Thu, Aug 11, 2022 at 10:49:13AM +0800, Yafang Shao wrote:
> On Thu, Aug 11, 2022 at 1:07 AM Shakeel Butt <shakeelb@google.com> wrote:
> >
> > On Wed, Aug 10, 2022 at 03:18:30PM +0000, Yafang Shao wrote:
> > > The memcg may be the root_mem_cgroup, in which case we shouldn't put it.
> >
> > No, it is ok to put root_mem_cgroup. css_put already handles the root
> > cgroups.
> >
>
> Ah, this commit log doesn't describe the issue clearly. I should improve it.
> The issue is that in bpf_map_get_memcg() it doesn't get the objcg if
> map->objcg is NULL (that can happen if the map belongs to the root
> memcg), so we shouldn't put the objcg if map->objcg is NULL neither in
> bpf_map_put_memcg().
Sorry I am still not understanding. We are not 'getting' objcg in
bpf_map_get_memcg(). We are 'getting' memcg from map->objcg and if that
is NULL the function is returning root memcg and putting root memcg is
totally fine. Or are you saying that root_mem_cgroup is NULL?
> Maybe the change below would be more reasonable ?
>
> +static void bpf_map_put_memcg(const struct bpf_map *map, struct
> mem_cgroup *memcg)
> +{
> + if (map->objcg)
> + mem_cgroup_put(memcg);
> +}
>
> --
> Regards
> Yafang
next prev parent reply other threads:[~2022-08-11 15:57 UTC|newest]
Thread overview: 33+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-08-10 15:18 [PATCH bpf-next 00/15] bpf: Introduce selectable memcg for bpf map Yafang Shao
2022-08-10 15:18 ` [PATCH bpf-next 01/15] bpf: Remove unneeded memset in queue_stack_map creation Yafang Shao
2022-08-10 15:18 ` [PATCH bpf-next 02/15] bpf: Use bpf_map_area_free instread of kvfree Yafang Shao
2022-08-10 15:18 ` [PATCH bpf-next 03/15] bpf: Make __GFP_NOWARN consistent in bpf map creation Yafang Shao
2022-08-10 15:18 ` [PATCH bpf-next 04/15] bpf: Use bpf_map_area_alloc consistently on " Yafang Shao
2022-08-10 15:18 ` [PATCH bpf-next 05/15] bpf: Fix incorrect mem_cgroup_put Yafang Shao
2022-08-10 17:07 ` Shakeel Butt
2022-08-11 2:49 ` Yafang Shao
2022-08-11 15:47 ` Shakeel Butt [this message]
2022-08-12 0:27 ` Yafang Shao
2022-08-12 5:33 ` Muchun Song
2022-08-12 11:25 ` Yafang Shao
2022-08-11 16:48 ` Roman Gushchin
2022-08-12 0:31 ` Yafang Shao
2022-08-10 15:18 ` [PATCH bpf-next 06/15] bpf: Define bpf_map_{get,put}_memcg for !CONFIG_MEMCG_KMEM Yafang Shao
2022-08-10 15:18 ` [PATCH bpf-next 07/15] bpf: Call bpf_map_init_from_attr() immediately after map creation Yafang Shao
2022-08-10 15:18 ` [PATCH bpf-next 08/15] bpf: Save memcg in bpf_map_init_from_attr() Yafang Shao
2022-08-10 15:18 ` [PATCH bpf-next 09/15] bpf: Use scoped-based charge in bpf_map_area_alloc Yafang Shao
2022-08-10 15:18 ` [PATCH bpf-next 10/15] bpf: Introduce new helpers bpf_ringbuf_pages_{alloc,free} Yafang Shao
2022-08-10 15:18 ` [PATCH bpf-next 11/15] bpf: Use bpf_map_kzalloc in arraymap Yafang Shao
2022-08-10 15:18 ` [PATCH bpf-next 12/15] bpf: Use bpf_map_kvcalloc in bpf_local_storage Yafang Shao
2022-08-10 15:18 ` [PATCH bpf-next 13/15] mm, memcg: Add new helper get_obj_cgroup_from_cgroup Yafang Shao
2022-08-11 16:16 ` Roman Gushchin
2022-08-12 0:35 ` Yafang Shao
2022-08-12 17:40 ` Roman Gushchin
2022-08-12 23:56 ` Yafang Shao
2022-08-13 18:30 ` Roman Gushchin
2022-08-14 2:35 ` Yafang Shao
2022-08-12 16:57 ` Shakeel Butt
2022-08-13 0:07 ` Yafang Shao
2022-08-10 15:18 ` [PATCH bpf-next 14/15] bpf: Add return value for bpf_map_init_from_attr Yafang Shao
2022-08-10 15:18 ` [PATCH bpf-next 15/15] bpf: Introduce selectable memcg for bpf map Yafang Shao
2022-08-10 19:00 ` [PATCH bpf-next 00/15] " patchwork-bot+netdevbpf
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