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Wed, 10 Aug 2022 08:18:53 -0700 (PDT) From: Yafang Shao To: ast@kernel.org, daniel@iogearbox.net, andrii@kernel.org, kafai@fb.com, songliubraving@fb.com, yhs@fb.com, john.fastabend@gmail.com, kpsingh@kernel.org, sdf@google.com, haoluo@google.com, jolsa@kernel.org, hannes@cmpxchg.org, mhocko@kernel.org, roman.gushchin@linux.dev, shakeelb@google.com, songmuchun@bytedance.com, akpm@linux-foundation.org Cc: netdev@vger.kernel.org, bpf@vger.kernel.org, linux-mm@kvack.org, Yafang Shao Subject: [PATCH bpf-next 05/15] bpf: Fix incorrect mem_cgroup_put Date: Wed, 10 Aug 2022 15:18:30 +0000 Message-Id: <20220810151840.16394-6-laoar.shao@gmail.com> X-Mailer: git-send-email 2.31.1 In-Reply-To: <20220810151840.16394-1-laoar.shao@gmail.com> References: <20220810151840.16394-1-laoar.shao@gmail.com> MIME-Version: 1.0 ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1660144735; a=rsa-sha256; cv=none; b=RXlclK2+6n58a+m94WmQqXe5E2N9UcgmPbLcoolXYZmurHXHWQd2VzF+pNAekU4u/YYUZz T//LdvtkE3phE/tIcQFtBiaJPgkIN7g33ovHgUDzp6J5rCxP70Ot4ORyrzC1mU5gZghkO7 Asl1K5Fb8ZkWM23SLMfl9+zBTWrgCMk= ARC-Authentication-Results: i=1; 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spf=pass (imf25.hostedemail.com: domain of laoar.shao@gmail.com designates 209.85.216.47 as permitted sender) smtp.mailfrom=laoar.shao@gmail.com; dmarc=pass (policy=none) header.from=gmail.com X-Rspam-User: X-Stat-Signature: ubkgg1n5fgy7inqmkfzozfas3ai4xoae X-Rspamd-Server: rspam05 X-HE-Tag: 1660144734-900506 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: The memcg may be the root_mem_cgroup, in which case we shouldn't put it. So a new helper bpf_map_put_memcg() is introduced to pair with bpf_map_get_memcg(). Fixes: 4201d9ab3e42 ("bpf: reparent bpf maps on memcg offlining") Cc: Roman Gushchin Cc: Shakeel Butt Signed-off-by: Yafang Shao --- kernel/bpf/syscall.c | 14 +++++++++++--- 1 file changed, 11 insertions(+), 3 deletions(-) diff --git a/kernel/bpf/syscall.c b/kernel/bpf/syscall.c index 83c7136..51ab8b1 100644 --- a/kernel/bpf/syscall.c +++ b/kernel/bpf/syscall.c @@ -441,6 +441,14 @@ static struct mem_cgroup *bpf_map_get_memcg(const struct bpf_map *map) return root_mem_cgroup; } +static void bpf_map_put_memcg(struct mem_cgroup *memcg) +{ + if (mem_cgroup_is_root(memcg)) + return; + + mem_cgroup_put(memcg); +} + void *bpf_map_kmalloc_node(const struct bpf_map *map, size_t size, gfp_t flags, int node) { @@ -451,7 +459,7 @@ void *bpf_map_kmalloc_node(const struct bpf_map *map, size_t size, gfp_t flags, old_memcg = set_active_memcg(memcg); ptr = kmalloc_node(size, flags | __GFP_ACCOUNT, node); set_active_memcg(old_memcg); - mem_cgroup_put(memcg); + bpf_map_put_memcg(memcg); return ptr; } @@ -465,7 +473,7 @@ void *bpf_map_kzalloc(const struct bpf_map *map, size_t size, gfp_t flags) old_memcg = set_active_memcg(memcg); ptr = kzalloc(size, flags | __GFP_ACCOUNT); set_active_memcg(old_memcg); - mem_cgroup_put(memcg); + bpf_map_put_memcg(memcg); return ptr; } @@ -480,7 +488,7 @@ void __percpu *bpf_map_alloc_percpu(const struct bpf_map *map, size_t size, old_memcg = set_active_memcg(memcg); ptr = __alloc_percpu_gfp(size, align, flags | __GFP_ACCOUNT); set_active_memcg(old_memcg); - mem_cgroup_put(memcg); + bpf_map_put_memcg(memcg); return ptr; }