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From: Shakeel Butt To: Yafang Shao Cc: akpm@linux-foundation.org, david@redhat.com, ziy@nvidia.com, baolin.wang@linux.alibaba.com, lorenzo.stoakes@oracle.com, Liam.Howlett@oracle.com, npache@redhat.com, ryan.roberts@arm.com, dev.jain@arm.com, hannes@cmpxchg.org, usamaarif642@gmail.com, gutierrez.asier@huawei-partners.com, willy@infradead.org, ast@kernel.org, daniel@iogearbox.net, andrii@kernel.org, ameryhung@gmail.com, rientjes@google.com, corbet@lwn.net, bpf@vger.kernel.org, linux-mm@kvack.org, linux-doc@vger.kernel.org Subject: Re: [PATCH v6 mm-new 02/10] mm: thp: add a new kfunc bpf_mm_get_mem_cgroup() Message-ID: References: <20250826071948.2618-1-laoar.shao@gmail.com> <20250826071948.2618-3-laoar.shao@gmail.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20250826071948.2618-3-laoar.shao@gmail.com> X-Migadu-Flow: FLOW_OUT X-Rspamd-Server: rspam12 X-Rspamd-Queue-Id: 192B48000C X-Stat-Signature: qj9x3ojass8a487carw4kixqcnd7oxbp X-Rspam-User: X-HE-Tag: 1756327571-995003 X-HE-Meta: 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 g0SEMBQh tOCDXhnTy9A3sf6rek9F0NthuxY8fI/zEYgbAdQCqL17YBxA= X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On Tue, Aug 26, 2025 at 03:19:40PM +0800, Yafang Shao wrote: > We will utilize this new kfunc bpf_mm_get_mem_cgroup() to retrieve the > associated mem_cgroup from the given @mm. The obtained mem_cgroup must > be released by calling bpf_put_mem_cgroup() as a paired operation. > > Signed-off-by: Yafang Shao > --- > mm/bpf_thp.c | 51 ++++++++++++++++++++++++++++++++++++++++++++++++++- > 1 file changed, 50 insertions(+), 1 deletion(-) > > diff --git a/mm/bpf_thp.c b/mm/bpf_thp.c > index fbff3b1bb988..b757e8f425fd 100644 > --- a/mm/bpf_thp.c > +++ b/mm/bpf_thp.c > @@ -175,10 +175,59 @@ static struct bpf_struct_ops bpf_bpf_thp_ops = { > .name = "bpf_thp_ops", > }; > > +__bpf_kfunc_start_defs(); > + > +/** > + * bpf_mm_get_mem_cgroup - Get the memory cgroup associated with a mm_struct. > + * @mm: The mm_struct to query > + * > + * The obtained mem_cgroup must be released by calling bpf_put_mem_cgroup(). > + * > + * Return: The associated mem_cgroup on success, or NULL on failure. Note that > + * this function depends on CONFIG_MEMCG being enabled - it will always return > + * NULL if CONFIG_MEMCG is not configured. > + */ > +__bpf_kfunc struct mem_cgroup *bpf_mm_get_mem_cgroup(struct mm_struct *mm) > +{ > + return get_mem_cgroup_from_mm(mm); > +} > + > +/** > + * bpf_put_mem_cgroup - Release a memory cgroup obtained from bpf_mm_get_mem_cgroup() > + * @memcg: The memory cgroup to release > + */ > +__bpf_kfunc void bpf_put_mem_cgroup(struct mem_cgroup *memcg) > +{ > +#ifdef CONFIG_MEMCG > + if (!memcg) > + return; > + css_put(&memcg->css); > +#endif Just use mem_cgroup_put() here. > +} > + > +__bpf_kfunc_end_defs(); > + > +BTF_KFUNCS_START(bpf_thp_ids) > +BTF_ID_FLAGS(func, bpf_mm_get_mem_cgroup, KF_TRUSTED_ARGS | KF_ACQUIRE | KF_RET_NULL) > +BTF_ID_FLAGS(func, bpf_put_mem_cgroup, KF_RELEASE) > +BTF_KFUNCS_END(bpf_thp_ids) > + > +static const struct btf_kfunc_id_set bpf_thp_set = { > + .owner = THIS_MODULE, > + .set = &bpf_thp_ids, > +}; > + > static int __init bpf_thp_ops_init(void) > { > - int err = register_bpf_struct_ops(&bpf_bpf_thp_ops, bpf_thp_ops); > + int err; > + > + err = register_btf_kfunc_id_set(BPF_PROG_TYPE_STRUCT_OPS, &bpf_thp_set); > + if (err) { > + pr_err("bpf_thp: Failed to register kfunc sets (%d)\n", err); > + return err; > + } > > + err = register_bpf_struct_ops(&bpf_bpf_thp_ops, bpf_thp_ops); > if (err) > pr_err("bpf_thp: Failed to register struct_ops (%d)\n", err); > return err; > -- > 2.47.3 >