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Miller" , Paolo Abeni , David Wei , netdev@vger.kernel.org, linux-kernel@vger.kernel.org, paulmck@kernel.org, kernel-team@meta.com, stable@vger.kernel.org Subject: Re: [PATCH net] netdevsim: disable local BH when scheduling NAPI Message-ID: References: <20250212-netdevsim-v1-1-20ece94daae8@debian.org> Precedence: bulk X-Mailing-List: netdev@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: On 02/12, Eric Dumazet wrote: > On Wed, Feb 12, 2025 at 7:34 PM Breno Leitao wrote: > > > > The netdevsim driver was getting NOHZ tick-stop errors during packet > > transmission due to pending softirq work when calling napi_schedule(). > > > > This is showing the following message when running netconsole selftest. > > > > NOHZ tick-stop error: local softirq work is pending, handler #08!!! > > > > Add local_bh_disable()/enable() around the napi_schedule() call to > > prevent softirqs from being handled during this xmit. > > > > Cc: stable@vger.kernel.org > > Fixes: 3762ec05a9fb ("netdevsim: add NAPI support") > > Suggested-by: Jakub Kicinski > > Signed-off-by: Breno Leitao > > --- > > drivers/net/netdevsim/netdev.c | 2 ++ > > 1 file changed, 2 insertions(+) > > > > diff --git a/drivers/net/netdevsim/netdev.c b/drivers/net/netdevsim/netdev.c > > index 42f247cbdceecbadf27f7090c030aa5bd240c18a..6aeb081b06da226ab91c49f53d08f465570877ae 100644 > > --- a/drivers/net/netdevsim/netdev.c > > +++ b/drivers/net/netdevsim/netdev.c > > @@ -87,7 +87,9 @@ static netdev_tx_t nsim_start_xmit(struct sk_buff *skb, struct net_device *dev) > > if (unlikely(nsim_forward_skb(peer_dev, skb, rq) == NET_RX_DROP)) > > goto out_drop_cnt; > > > > + local_bh_disable(); > > napi_schedule(&rq->napi); > > + local_bh_enable(); > > > > I thought all ndo_start_xmit() were done under local_bh_disable() > > Could you give more details ? Not 100% sure this patch is the culprit, but looks related: https://netdev-3.bots.linux.dev/vmksft-net-drv-dbg/results/989901/5-netcons-fragmented-msg-sh/stderr --- pw-bot: cr