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Sun, 17 Aug 2025 22:55:44 -0700 (PDT) Received: from localhost.localdomain ([39.144.105.14]) by smtp.gmail.com with ESMTPSA id 98e67ed59e1d1-323439961c9sm7003413a91.13.2025.08.17.22.55.38 (version=TLS1_3 cipher=TLS_CHACHA20_POLY1305_SHA256 bits=256/256); Sun, 17 Aug 2025 22:55:44 -0700 (PDT) From: Yafang Shao To: 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 Cc: bpf@vger.kernel.org, linux-mm@kvack.org, Yafang Shao Subject: [RFC PATCH v5 mm-new 3/5] mm: thp: add a new kfunc bpf_mm_get_task() Date: Mon, 18 Aug 2025 13:55:08 +0800 Message-Id: <20250818055510.968-4-laoar.shao@gmail.com> X-Mailer: git-send-email 2.37.1 (Apple Git-137.1) In-Reply-To: <20250818055510.968-1-laoar.shao@gmail.com> References: <20250818055510.968-1-laoar.shao@gmail.com> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Stat-Signature: u39f9unta6sz469gcz611ia6djjm6eww X-Rspam-User: X-Rspamd-Queue-Id: E60C28000B X-Rspamd-Server: rspam01 X-HE-Tag: 1755496545-555396 X-HE-Meta: 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 0uKKaDj1 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 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: We will utilize this new kfunc bpf_mm_get_task() to retrieve the associated task_struct from the given @mm. The obtained task_struct must be released by calling bpf_task_release() as a paired operation. Signed-off-by: Yafang Shao --- mm/bpf_thp.c | 34 ++++++++++++++++++++++++++++++++++ 1 file changed, 34 insertions(+) diff --git a/mm/bpf_thp.c b/mm/bpf_thp.c index bdcf6f6af99b..8ed1bf0d7f4d 100644 --- a/mm/bpf_thp.c +++ b/mm/bpf_thp.c @@ -205,11 +205,45 @@ __bpf_kfunc void bpf_put_mem_cgroup(struct mem_cgroup *memcg) #endif } +/** + * bpf_mm_get_task - Get the task struct associated with a mm_struct. + * @mm: The mm_struct to query + * + * The obtained task_struct must be released by calling bpf_task_release(). + * + * Return: The associated task_struct 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 task_struct *bpf_mm_get_task(struct mm_struct *mm) +{ +#ifdef CONFIG_MEMCG + struct task_struct *task; + + if (!mm) + return NULL; + rcu_read_lock(); + task = rcu_dereference(mm->owner); + if (!task) + goto out; + if (!refcount_inc_not_zero(&task->rcu_users)) + goto out; + + rcu_read_unlock(); + return task; + +out: + rcu_read_unlock(); +#endif + return NULL; +} + __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_ID_FLAGS(func, bpf_mm_get_task, KF_TRUSTED_ARGS | KF_ACQUIRE | KF_RET_NULL) BTF_KFUNCS_END(bpf_thp_ids) static const struct btf_kfunc_id_set bpf_thp_set = { -- 2.47.3