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Tue, 29 Jul 2025 02:18:53 -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 Cc: bpf@vger.kernel.org, linux-mm@kvack.org, Yafang Shao Subject: [RFC PATCH v4 3/4] mm: thp: add a new kfunc bpf_mm_get_task() Date: Tue, 29 Jul 2025 17:18:06 +0800 Message-Id: <20250729091807.84310-4-laoar.shao@gmail.com> X-Mailer: git-send-email 2.37.1 (Apple Git-137.1) In-Reply-To: <20250729091807.84310-1-laoar.shao@gmail.com> References: <20250729091807.84310-1-laoar.shao@gmail.com> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Rspamd-Queue-Id: BF5B5C0006 X-Stat-Signature: qs9s7ehyd9mxszodgdw1mrmjqhbt9gzk X-Rspam-User: X-Rspamd-Server: rspam07 X-HE-Tag: 1753780735-49853 X-HE-Meta: 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 yO4GXy4X 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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 040f988dbdbd..3b10a97acc31 100644 --- a/mm/bpf_thp.c +++ b/mm/bpf_thp.c @@ -191,11 +191,45 @@ __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 = { -- 2.43.5