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charset=iso-8859-1 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: 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! > >Best regards >-- >Marek Szyprowski, PhD >Samsung R&D Institute Poland >