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Wed, 11 Mar 2026 06:03:22 -0700 (PDT) From: Kumar Kartikeya Dwivedi To: martin.lau@linux.dev Cc: ameryhung@gmail.com, andrii@kernel.org, ast@kernel.org, bpf@vger.kernel.org, daniel@iogearbox.net, eddyz87@gmail.com, grbell@redhat.com, haoluo@google.com, john.fastabend@gmail.com, jolsa@kernel.org, kpsingh@kernel.org, memxor@gmail.com, sdf@fomichev.me, song@kernel.org, yonghong.song@linux.dev Subject: [PATCH] bpf: Release module BTF IDR before module unload Date: Wed, 11 Mar 2026 06:03:21 -0700 Message-ID: <20260311130321.1055808-1-memxor@gmail.com> X-Mailer: git-send-email 2.52.0 In-Reply-To: References: Precedence: bulk X-Mailing-List: bpf@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Signed-off-by: Kumar Kartikeya Dwivedi --- kernel/bpf/btf.c | 15 ++++++++++++++- 1 file changed, 14 insertions(+), 1 deletion(-) diff --git a/kernel/bpf/btf.c b/kernel/bpf/btf.c index 09fcbb125155..d18e218049ed 100644 --- a/kernel/bpf/btf.c +++ b/kernel/bpf/btf.c @@ -1883,10 +1883,17 @@ void btf_get(struct btf *btf) refcount_inc(&btf->refcnt); } +static bool btf_is_module(const struct btf *btf); + void btf_put(struct btf *btf) { if (btf && refcount_dec_and_test(&btf->refcnt)) { - btf_free_id(btf); + /* + * IDR for module BTFs is freed when module's BTF reference is + * dropped, which may happen before the final put. + */ + if (!btf_is_module(btf)) + btf_free_id(btf); call_rcu(&btf->rcu, btf_free_rcu); } } @@ -8383,6 +8390,12 @@ static int btf_module_notify(struct notifier_block *nb, unsigned long op, if (btf_mod->module != module) continue; + /* + * For modules, we do the freeing of BTF IDR as soon as + * module goes away to disable BTF discovery, since the + * btf_try_get_module() on such BTFs will fail. + */ + btf_free_id(btf_mod->btf); list_del(&btf_mod->list); if (btf_mod->sysfs_attr) sysfs_remove_bin_file(btf_kobj, btf_mod->sysfs_attr); -- 2.52.0