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Miller" , Eric Dumazet , Jakub Kicinski , Paolo Abeni , Jiri Pirko , Simon Horman , Daniel Borkmann , Lorenzo Bianconi , Coco Li , Wei Wang , Alexander Duyck , Hannes Frederic Sowa , linux-kernel@vger.kernel.org, rcu@vger.kernel.org, bpf@vger.kernel.org, kernel-team@cloudflare.com, Joel Fernandes , "Paul E. McKenney" , Toke =?utf-8?Q?H=C3=B8iland-J=C3=B8rgensen?= , Alexei Starovoitov , Steven Rostedt , mark.rutland@arm.com, Jesper Dangaard Brouer Subject: [PATCH v4 net 3/3] bpf: report RCU QS in cpumap kthread Message-ID: References: Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" When there are heavy load, cpumap kernel threads can be busy polling packets from redirect queues and block out RCU tasks from reaching quiescent states. It is insufficient to just call cond_resched() in such context. Periodically raise a consolidated RCU QS before cond_resched fixes the problem. Fixes: 6710e1126934 ("bpf: introduce new bpf cpu map type BPF_MAP_TYPE_CPUM= AP") Reviewed-by: Jesper Dangaard Brouer Signed-off-by: Yan Zhai --- kernel/bpf/cpumap.c | 3 +++ 1 file changed, 3 insertions(+) diff --git a/kernel/bpf/cpumap.c b/kernel/bpf/cpumap.c index ef82ffc90cbe..8f1d390bcbde 100644 --- a/kernel/bpf/cpumap.c +++ b/kernel/bpf/cpumap.c @@ -262,6 +262,7 @@ static int cpu_map_bpf_prog_run(struct bpf_cpu_map_entr= y *rcpu, void **frames, static int cpu_map_kthread_run(void *data) { struct bpf_cpu_map_entry *rcpu =3D data; + unsigned long last_qs =3D jiffies; =20 complete(&rcpu->kthread_running); set_current_state(TASK_INTERRUPTIBLE); @@ -287,10 +288,12 @@ static int cpu_map_kthread_run(void *data) if (__ptr_ring_empty(rcpu->queue)) { schedule(); sched =3D 1; + last_qs =3D jiffies; } else { __set_current_state(TASK_RUNNING); } } else { + rcu_softirq_qs_periodic(last_qs); sched =3D cond_resched(); } =20 --=20 2.30.2