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Tue, 26 Aug 2025 00:20:42 -0700 (PDT) Received: from localhost.localdomain ([101.82.213.56]) by smtp.gmail.com with ESMTPSA id d2e1a72fcca58-770401ecc51sm9686052b3a.75.2025.08.26.00.20.29 (version=TLS1_3 cipher=TLS_CHACHA20_POLY1305_SHA256 bits=256/256); Tue, 26 Aug 2025 00:20:42 -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, corbet@lwn.net Cc: bpf@vger.kernel.org, linux-mm@kvack.org, linux-doc@vger.kernel.org, Yafang Shao Subject: [PATCH v6 mm-new 03/10] mm: thp: add a new kfunc bpf_mm_get_task() Date: Tue, 26 Aug 2025 15:19:41 +0800 Message-Id: <20250826071948.2618-4-laoar.shao@gmail.com> X-Mailer: git-send-email 2.37.1 (Apple Git-137.1) In-Reply-To: <20250826071948.2618-1-laoar.shao@gmail.com> References: <20250826071948.2618-1-laoar.shao@gmail.com> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Rspamd-Server: rspam02 X-Rspamd-Queue-Id: CB4E310000D X-Stat-Signature: 16bh4fdsno9d6jneot7dwweofpuqh3bu X-Rspam-User: X-HE-Tag: 1756192843-606728 X-HE-Meta: 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 5sJ+fl8E zNkzCV47zUDcyeFj7/riYR0CMuOphmZ/MyDN41dOzxAr35QO3+sGFRicqYz5/qVyK0dRhYwTbYz8xjaW4CZNQa/vYne3g3rxzFgkJaz9Q6iLL9MWwEhktxtIptLJQ0VTk+3oiyiCzOVb8Q0ZBVyStDpFg9XXuwxQ1pIbsKKsLQ9hCBJcLFI/r6AHSsr+WcuV6oUCTIhHZNqWM3v4MMPXAs7nHLLnHurT7+s14fyoKGVbcUX5yfC8AupvKevUj9ukQlDuYBB8kGduEbxdLiejHEtbH+XZfaJMka6oEa8okOHjeMSL5Yf4+O2asyBInbBqO6LNF2tjA7RLbjyn6D5ierf24aYrwO6W5x0++HMPTV14W8GA+Aj97x0eZXOPR6nE+y5f0gNvPj/EXtC45slvtgJoJG1yXZQ0kGbqPJAbOcEDhnlKq9p+t1DpCCP3K9Eh6gR2gU7WoZh/8Z84Em9gGkLmUBK/oI1fFLeutxeQaQwaOF6Cm/IeXtRqCNo8AGHM0j3l6lETqYRGcBLXymGyZ/BMHeV2baSjoAPYDDGb6ewke6TYl5QL+SAKTW8ET5H7b7Aq7JFo+O/0PAYne+SlomkY+xw== 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 b757e8f425fd..46b3bc96359e 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