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[37.48.50.18]) by smtp.gmail.com with ESMTPSA id ffacd0b85a97d-36e4cfefe71sm12788383f8f.62.2024.08.14.05.16.36 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 14 Aug 2024 05:16:36 -0700 (PDT) Date: Wed, 14 Aug 2024 14:16:35 +0200 From: Jiri Pirko To: Marek Szyprowski Cc: netdev@vger.kernel.org, davem@davemloft.net, edumazet@google.com, kuba@kernel.org, pabeni@redhat.com, mst@redhat.com, jasowang@redhat.com, xuanzhuo@linux.alibaba.com, virtualization@lists.linux.dev, ast@kernel.org, daniel@iogearbox.net, hawk@kernel.org, john.fastabend@gmail.com, dave.taht@gmail.com, kerneljasonxing@gmail.com, hengqi@linux.alibaba.com Subject: Re: [PATCH net-next v3] virtio_net: add support for Byte Queue Limits Message-ID: References: <20240618144456.1688998-1-jiri@resnulli.us> <2d98cdcb-19c6-4a70-b8c6-b978b40663ee@samsung.com> Precedence: bulk X-Mailing-List: virtualization@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <2d98cdcb-19c6-4a70-b8c6-b978b40663ee@samsung.com> Wed, Aug 14, 2024 at 11:17:35AM CEST, m.szyprowski@samsung.com wrote: >On 14.08.2024 09:49, Jiri Pirko wrote: >> Mon, Aug 12, 2024 at 06:55:26PM CEST, m.szyprowski@samsung.com wrote: >>> On 12.08.2024 18:47, Jiri Pirko wrote: >>>> Mon, Aug 12, 2024 at 04:57:24PM CEST, m.szyprowski@samsung.com wrote: >>>>> On 18.06.2024 16:44, Jiri Pirko wrote: >>>>>> From: Jiri Pirko >>>>>> >>>>>> Add support for Byte Queue Limits (BQL). >>>>>> >>>>>> Tested on qemu emulated virtio_net device with 1, 2 and 4 queues. >>>>>> Tested with fq_codel and pfifo_fast. Super netperf with 50 threads is >>>>>> running in background. Netperf TCP_RR results: >>>>>> >>>>>> NOBQL FQC 1q: 159.56 159.33 158.50 154.31 agv: 157.925 >>>>>> NOBQL FQC 2q: 184.64 184.96 174.73 174.15 agv: 179.62 >>>>>> NOBQL FQC 4q: 994.46 441.96 416.50 499.56 agv: 588.12 >>>>>> NOBQL PFF 1q: 148.68 148.92 145.95 149.48 agv: 148.2575 >>>>>> NOBQL PFF 2q: 171.86 171.20 170.42 169.42 agv: 170.725 >>>>>> NOBQL PFF 4q: 1505.23 1137.23 2488.70 3507.99 agv: 2159.7875 >>>>>> BQL FQC 1q: 1332.80 1297.97 1351.41 1147.57 agv: 1282.4375 >>>>>> BQL FQC 2q: 768.30 817.72 864.43 974.40 agv: 856.2125 >>>>>> BQL FQC 4q: 945.66 942.68 878.51 822.82 agv: 897.4175 >>>>>> BQL PFF 1q: 149.69 151.49 149.40 147.47 agv: 149.5125 >>>>>> BQL PFF 2q: 2059.32 798.74 1844.12 381.80 agv: 1270.995 >>>>>> BQL PFF 4q: 1871.98 4420.02 4916.59 13268.16 agv: 6119.1875 >>>>>> >>>>>> Signed-off-by: Jiri Pirko >>>>>> --- >>>>>> v2->v3: >>>>>> - fixed the switch from/to orphan mode while skbs are yet to be >>>>>> completed by using the second least significant bit in virtqueue >>>>>> token pointer to indicate skb is orphan. Don't account orphan >>>>>> skbs in completion. >>>>>> - reorganized parallel skb/xdp free stats accounting to napi/others. >>>>>> - fixed kick condition check in orphan mode >>>>>> v1->v2: >>>>>> - moved netdev_tx_completed_queue() call into __free_old_xmit(), >>>>>> propagate use_napi flag to __free_old_xmit() and only call >>>>>> netdev_tx_completed_queue() in case it is true >>>>>> - added forgotten call to netdev_tx_reset_queue() >>>>>> - fixed stats for xdp packets >>>>>> - fixed bql accounting when __free_old_xmit() is called from xdp path >>>>>> - handle the !use_napi case in start_xmit() kick section >>>>>> --- >>>>>> drivers/net/virtio_net.c | 81 ++++++++++++++++++++++++++++------------ >>>>>> 1 file changed, 57 insertions(+), 24 deletions(-) >>>>> I've recently found an issue with virtio-net driver and system >>>>> suspend/resume. Bisecting pointed to the c8bd1f7f3e61 ("virtio_net: add >>>>> support for Byte Queue Limits") commit and this patch. Once it got >>>>> merged to linux-next and then Linus trees, the driver occasionally >>>>> crashes with the following log (captured on QEMU's ARM 32bit 'virt' >>>>> machine): >>>>> >>>>> root@target:~# time rtcwake -s10 -mmem >>>>> rtcwake: wakeup from "mem" using /dev/rtc0 at Sat Aug 10 12:40:26 2024 >>>>> PM: suspend entry (s2idle) >>>>> Filesystems sync: 0.000 seconds >>>>> Freezing user space processes >>>>> Freezing user space processes completed (elapsed 0.006 seconds) >>>>> OOM killer disabled. >>>>> Freezing remaining freezable tasks >>>>> Freezing remaining freezable tasks completed (elapsed 0.001 seconds) >>>>> ------------[ cut here ]------------ >>>>> kernel BUG at lib/dynamic_queue_limits.c:99! >>>>> Internal error: Oops - BUG: 0 [#1] SMP ARM >>>>> Modules linked in: bluetooth ecdh_generic ecc libaes >>>>> CPU: 1 PID: 1282 Comm: rtcwake Not tainted >>>>> 6.10.0-rc3-00732-gc8bd1f7f3e61 #15240 >>>>> Hardware name: Generic DT based system >>>>> PC is at dql_completed+0x270/0x2cc >>>>> LR is at __free_old_xmit+0x120/0x198 >>>>> pc : []    lr : []    psr: 80000013 >>>>> ... >>>>> Flags: Nzcv  IRQs on  FIQs on  Mode SVC_32  ISA ARM  Segment none >>>>> Control: 10c5387d  Table: 43a4406a  DAC: 00000051 >>>>> ... >>>>> Process rtcwake (pid: 1282, stack limit = 0xfbc21278) >>>>> Stack: (0xe0805e80 to 0xe0806000) >>>>> ... >>>>> Call trace: >>>>>  dql_completed from __free_old_xmit+0x120/0x198 >>>>>  __free_old_xmit from free_old_xmit+0x44/0xe4 >>>>>  free_old_xmit from virtnet_poll_tx+0x88/0x1b4 >>>>>  virtnet_poll_tx from __napi_poll+0x2c/0x1d4 >>>>>  __napi_poll from net_rx_action+0x140/0x2b4 >>>>>  net_rx_action from handle_softirqs+0x11c/0x350 >>>>>  handle_softirqs from call_with_stack+0x18/0x20 >>>>>  call_with_stack from do_softirq+0x48/0x50 >>>>>  do_softirq from __local_bh_enable_ip+0xa0/0xa4 >>>>>  __local_bh_enable_ip from virtnet_open+0xd4/0x21c >>>>>  virtnet_open from virtnet_restore+0x94/0x120 >>>>>  virtnet_restore from virtio_device_restore+0x110/0x1f4 >>>>>  virtio_device_restore from dpm_run_callback+0x3c/0x100 >>>>>  dpm_run_callback from device_resume+0x12c/0x2a8 >>>>>  device_resume from dpm_resume+0x12c/0x1e0 >>>>>  dpm_resume from dpm_resume_end+0xc/0x18 >>>>>  dpm_resume_end from suspend_devices_and_enter+0x1f0/0x72c >>>>>  suspend_devices_and_enter from pm_suspend+0x270/0x2a0 >>>>>  pm_suspend from state_store+0x68/0xc8 >>>>>  state_store from kernfs_fop_write_iter+0x10c/0x1cc >>>>>  kernfs_fop_write_iter from vfs_write+0x2b0/0x3dc >>>>>  vfs_write from ksys_write+0x5c/0xd4 >>>>>  ksys_write from ret_fast_syscall+0x0/0x54 >>>>> Exception stack(0xe8bf1fa8 to 0xe8bf1ff0) >>>>> ... >>>>> ---[ end trace 0000000000000000 ]--- >>>>> Kernel panic - not syncing: Fatal exception in interrupt >>>>> ---[ end Kernel panic - not syncing: Fatal exception in interrupt ]--- >>>>> >>>>> I have fully reproducible setup for this issue. Reverting it together >>>>> with f8321fa75102 ("virtio_net: Fix napi_skb_cache_put warning") (due to >>>>> some code dependencies) fixes this issue on top of Linux v6.11-rc1 and >>>>> recent linux-next releases. Let me know if I can help debugging this >>>>> issue further and help fixing. >>>> Will fix this tomorrow. In the meantime, could you provide full >>>> reproduce steps? >>> Well, it is easy to reproduce it simply by calling >>> >>> # time rtcwake -s10 -mmem >>> >>> a few times and sooner or later it will cause a kernel panic. >> I found the problem. Following patch will help: >> >> >> diff --git a/drivers/net/virtio_net.c b/drivers/net/virtio_net.c >> index 3f10c72743e9..c6af18948092 100644 >> --- a/drivers/net/virtio_net.c >> +++ b/drivers/net/virtio_net.c >> @@ -2867,8 +2867,8 @@ static int virtnet_enable_queue_pair(struct virtnet_info *vi, int qp_index) >> if (err < 0) >> goto err_xdp_reg_mem_model; >> >> - virtnet_napi_enable(vi->rq[qp_index].vq, &vi->rq[qp_index].napi); >> netdev_tx_reset_queue(netdev_get_tx_queue(vi->dev, qp_index)); >> + virtnet_napi_enable(vi->rq[qp_index].vq, &vi->rq[qp_index].napi); >> virtnet_napi_tx_enable(vi, vi->sq[qp_index].vq, &vi->sq[qp_index].napi); >> >> return 0; >> >> >> Will submit the patch in a jiff. Thanks! > >Confirmed. The above change fixed this issue in my tests. > >Feel free to add: > >Reported-by: Marek Szyprowski >Tested-by: Marek Szyprowski Thanks! > >Best regards >-- >Marek Szyprowski, PhD >Samsung R&D Institute Poland >