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([2601:282:800:fd80:f02b:2058:cbd0:634d]) by smtp.googlemail.com with ESMTPSA id a6sm39374586pgd.67.2019.04.24.10.13.44 (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Wed, 24 Apr 2019 10:13:46 -0700 (PDT) To: makita.toshiaki@lab.ntt.co.jp, "Michael S. Tsirkin" , Jesper Dangaard Brouer , =?UTF-8?Q?Toke_H=c3=b8iland-J=c3=b8rgensen?= , "netdev@vger.kernel.org" From: David Ahern Subject: virtio_net: suspicious RCU usage with xdp Message-ID: Date: Wed, 24 Apr 2019 11:13:42 -0600 User-Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.14; rv:52.0) Gecko/20100101 Thunderbird/52.9.1 MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit Sender: netdev-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org seeing an RCU warning testing xdp with virtio net. net-next as of commit b2f97f7de2f6a4df8e431330cf467576486651c5. No obvious changes so hoping this rings a bell with someone else. [ 121.990304] ============================= [ 121.991488] WARNING: suspicious RCU usage [ 121.992392] 5.1.0-rc5+ #60 Not tainted [ 121.993220] ----------------------------- [ 121.994158] /home/dsa/kernel-3.git/drivers/net/virtio_net.c:516 suspicious rcu_dereference_check() usage! [ 121.996284] other info that might help us debug this: [ 121.997988] rcu_scheduler_active = 2, debug_locks = 1 [ 121.999321] no locks held by swapper/1/0. [ 122.000328] stack backtrace: [ 122.001253] CPU: 1 PID: 0 Comm: swapper/1 Not tainted 5.1.0-rc5+ #60 [ 122.002474] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.11.1-1 04/01/2014 [ 122.004141] Call Trace: [ 122.004651] [ 122.005082] dump_stack+0x7e/0xbb [ 122.005757] lockdep_rcu_suspicious+0x102/0x10b [ 122.006654] virtnet_xdp_xmit+0x104/0x4fe [ 122.007447] ? kasan_check_read+0x11/0x13 [ 122.008267] ? mergeable_rx_buffer_size_show+0x163/0x163 [ 122.009299] ? __asan_loadN+0xf/0x11 [ 122.010010] ? pvclock_clocksource_read+0xfa/0x189 [ 122.010975] bq_xmit_all+0xdc/0x358 [ 122.011699] __dev_map_flush+0xc2/0xef [ 122.012472] xdp_do_flush_map+0x5b/0x74 [ 122.013238] virtnet_poll+0x58f/0x679