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[66.187.233.206]) by smtp.gmail.com with ESMTPSA id j85sm12186207qke.20.2020.03.12.07.03.32 (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Thu, 12 Mar 2020 07:03:33 -0700 (PDT) Message-ID: <1584021811.7365.180.camel@lca.pw> Subject: Re: [PATCH v4 2/2] net: memcg: late association of sock to memcg From: Qian Cai To: Shakeel Butt , Eric Dumazet , Roman Gushchin Cc: Johannes Weiner , Michal Hocko , Greg Thelen , Andrew Morton , "David S . Miller" , Alexey Kuznetsov , Hideaki YOSHIFUJI , netdev@vger.kernel.org, linux-mm@kvack.org, cgroups@vger.kernel.org, linux-kernel@vger.kernel.org Date: Thu, 12 Mar 2020 10:03:31 -0400 In-Reply-To: <20200310051606.33121-2-shakeelb@google.com> References: <20200310051606.33121-1-shakeelb@google.com> <20200310051606.33121-2-shakeelb@google.com> Content-Type: text/plain; charset="UTF-8" X-Mailer: Evolution 3.22.6 (3.22.6-10.el7) Mime-Version: 1.0 Content-Transfer-Encoding: quoted-printable 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: On Mon, 2020-03-09 at 22:16 -0700, Shakeel Butt wrote: > diff --git a/net/ipv4/inet_connection_sock.c b/net/ipv4/inet_connection= _sock.c > index a4db79b1b643..65a3b2565102 100644 > --- a/net/ipv4/inet_connection_sock.c > +++ b/net/ipv4/inet_connection_sock.c > @@ -482,6 +482,26 @@ struct sock *inet_csk_accept(struct sock *sk, int = flags, int *err, bool kern) > } > spin_unlock_bh(&queue->fastopenq.lock); > } > + > + if (mem_cgroup_sockets_enabled) { > + int amt; > + > + /* atomically get the memory usage, set and charge the > + * sk->sk_memcg. > + */ > + lock_sock(newsk); Here we have a deadlock, [=C2=A0=C2=A0362.620977][ T4106] WARNING: possible recursive locking dete= cted [=C2=A0=C2=A0362.626983][ T4106] 5.6.0-rc5-next-20200312+ #5 Tainted: G=C2= =A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0= L=C2=A0=C2=A0=C2=A0 [=C2=A0=C2=A0362.633941][ T4106] ----------------------------------------= ---- [=C2=A0=C2=A0362.639944][ T4106] sshd/4106 is trying to acquire lock: [=C2=A0=C2=A0362.645251][ T4106] 7bff008a2eae6330 (sk_lock-AF_INET){+.+.}= , at: inet_csk_accept+0x370/0x45c inet_csk_accept at net/ipv4/inet_connection_sock.c:497 [=C2=A0=C2=A0362.653791][ T4106]=C2=A0 [=C2=A0=C2=A0362.653791][ T4106] but task is already holding lock: [=C2=A0=C2=A0362.661007][ T4106] c0ff008a2eae9430 (sk_lock-AF_INET){+.+.}= , at: inet_csk_accept+0x48/0x45c inet_csk_accept at net/ipv4/inet_connection_sock.c:451 [=C2=A0=C2=A0362.669452][ T4106]=C2=A0 [=C2=A0=C2=A0362.669452][ T4106] other info that might help us debug this= : [=C2=A0=C2=A0362.677364][ T4106]=C2=A0=C2=A0Possible unsafe locking scena= rio: [=C2=A0=C2=A0362.677364][ T4106]=C2=A0 [=C2=A0=C2=A0362.684666][ T4106]=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0= =C2=A0CPU0 [=C2=A0=C2=A0362.687801][ T4106]=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0= =C2=A0---- [=C2=A0=C2=A0362.690937][ T4106]=C2=A0=C2=A0=C2=A0lock(sk_lock-AF_INET); [=C2=A0=C2=A0362.695204][ T4106]=C2=A0=C2=A0=C2=A0lock(sk_lock-AF_INET); [=C2=A0=C2=A0362.699472][ T4106]=C2=A0 [=C2=A0=C2=A0362.699472][ T4106]=C2=A0=C2=A0*** DEADLOCK *** [=C2=A0=C2=A0362.699472][ T4106]=C2=A0 [=C2=A0=C2=A0362.707469][ T4106]=C2=A0=C2=A0May be due to missing lock ne= sting notation [=C2=A0=C2=A0362.707469][ T4106]=C2=A0 [=C2=A0=C2=A0362.715643][ T4106] 1 lock held by sshd/4106: [=C2=A0=C2=A0362.719993][ T4106]=C2=A0=C2=A0#0: c0ff008a2eae9430 (sk_lock= -AF_INET){+.+.}, at: inet_csk_accept+0x48/0x45c [=C2=A0=C2=A0362.728874][ T4106]=C2=A0 [=C2=A0=C2=A0362.728874][ T4106] stack backtrace: [=C2=A0=C2=A0362.734622][ T4106] CPU: 22 PID: 4106 Comm: sshd Tainted: G=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0= =C2=A0L=C2=A0=C2=A0=C2=A0=C2=A05.6.0-rc5-next-20200312+ #5 [=C2=A0=C2=A0362.744096][ T4106] Hardware name: HPE Apollo 70=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0= =C2=A0/C01_APACHE_MB=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0= , BIOS L50_5.13_1.11 06/18/2019 [=C2=A0=C2=A0362.754525][ T4106] Call trace: [=C2=A0=C2=A0362.757667][ T4106]=C2=A0=C2=A0dump_backtrace+0x0/0x2c8 [=C2=A0=C2=A0362.762022][ T4106]=C2=A0=C2=A0show_stack+0x20/0x2c [=C2=A0=C2=A0362.766032][ T4106]=C2=A0=C2=A0dump_stack+0xe8/0x150 [=C2=A0=C2=A0362.770128][ T4106]=C2=A0=C2=A0validate_chain+0x2f08/0x35e0 [=C2=A0=C2=A0362.774830][ T4106]=C2=A0=C2=A0__lock_acquire+0x868/0xc2c [=C2=A0=C2=A0362.779358][ T4106]=C2=A0=C2=A0lock_acquire+0x320/0x360 [=C2=A0=C2=A0362.783715][ T4106]=C2=A0=C2=A0lock_sock_nested+0x9c/0xd8 [=C2=A0=C2=A0362.788243][ T4106]=C2=A0=C2=A0inet_csk_accept+0x370/0x45c [=C2=A0=C2=A0362.792861][ T4106]=C2=A0=C2=A0inet_accept+0x80/0x1cc [=C2=A0=C2=A0362.797045][ T4106]=C2=A0=C2=A0__sys_accept4_file+0x1b0/0x2b= c [=C2=A0=C2=A0362.801921][ T4106]=C2=A0=C2=A0__arm64_sys_accept+0x74/0xc8 [=C2=A0=C2=A0362.806625][ T4106]=C2=A0=C2=A0do_el0_svc+0x170/0x240 [=C2=A0=C2=A0362.810807][ T4106]=C2=A0=C2=A0el0_sync_handler+0x150/0x250 [=C2=A0=C2=A0362.815509][ T4106]=C2=A0=C2=A0el0_sync+0x164/0x180 > + > + /* The sk has not been accepted yet, no need to look at > + * sk->sk_wmem_queued. > + */ > + amt =3D sk_mem_pages(newsk->sk_forward_alloc + > + atomic_read(&sk->sk_rmem_alloc)); > + mem_cgroup_sk_alloc(newsk); > + if (newsk->sk_memcg && amt) > + mem_cgroup_charge_skmem(newsk->sk_memcg, amt); > + > + release_sock(newsk); > + } > out: > release_sock(sk); > if (req)