I realize now we had a second issue on arm64 on Ubuntu 20.04 a bit before that resulted from the same patch, we got around that one without looking deeply by changing kernels. At the time we declined to investigate.
So, I have a further question: so, I suspect the reason this slipped through Ubuntu's QA process is it probably only uses qemu, which must work at least somewhat well enough. I don't know how the author (Jason) found he had introduced a defect so quickly upstream, but the issue existed in upstream linux only briefly, and got magnified by the Ubuntu release process. A simple answer would be: I will run proposed kernels and write in if anything weird happens. But I imagine Ubuntu has a more involved test suite to qualify kernels. Can an alternative vmm somehow get into the testing matrix? It's also possible that Firecracker and Crosvm would have suffered this issue, as they all share Rust crates to do some of the implementation. Secondly, are there frequently refreshed upstream packages of kernels (vanilla, ubuntu modified both) in apt repositories I could add to this testing matrix, to catch bugs as close to the source and as early as possible, including in linux upstream? As an administrative matter, I could somewhat easily test boot and some workload on kernels a, b, c, etcetera if the packaging is there. It's no doubt worth our while to check basic functionality working regularly, but I don't think we can build up Ubuntu's full acceptance infrastructure, which would be the next level of sophistication. There may also be some intermediate methods, e.g. if there's some Ubuntu tests we can run in a VM, even if it is not all of them. Let me know if this is the place to discuss this. It's obviously not *exactly* the right place...perhaps a mailing list? But maybe the answers are simple enough. -- You received this bug notification because you are a member of Kernel Packages, which is subscribed to linux in Ubuntu. https://bugs.launchpad.net/bugs/2045443 Title: Ubuntu-5.15.0-89.99 breaks virtio-net spec and doesn't boot Status in linux package in Ubuntu: Fix Released Status in linux source package in Jammy: Fix Committed Bug description: I use a non-qemu VMM, cloud-hypervisor. It looks like a patch was applied, that introduced a bug, a week later another patch got written to fix that bug, and that second patch was not applied in Ubuntu's release, but is seen in Greg KH's 5.15 branch. The result of the bug is the kernel will not boot. Cumulative diff: ``` > git diff Ubuntu-5.15.0-86.96 Ubuntu-5.15.0-89.99 drivers/net/virtio_net.c diff --git a/drivers/net/virtio_net.c b/drivers/net/virtio_net.c index 0351f86494f1..af335f8266c2 100644 --- a/drivers/net/virtio_net.c +++ b/drivers/net/virtio_net.c @@ -3319,6 +3319,8 @@ static int virtnet_probe(struct virtio_device *vdev) } } + _virtnet_set_queues(vi, vi->curr_queue_pairs); + /* serialize netdev register + virtio_device_ready() with ndo_open() */ rtnl_lock(); @@ -3339,8 +3341,6 @@ static int virtnet_probe(struct virtio_device *vdev) goto free_unregister_netdev; } - virtnet_set_queues(vi, vi->curr_queue_pairs); - /* Assume link up if device can't report link status, otherwise get link status from config. */ netif_carrier_off(dev); ``` Blamed Commit: ``` commit 5e0545ef5682562ffef072138d9340ea36a2ebc9 Author: Jason Wang <jasow...@redhat.com> Date: Tue Jul 25 03:20:49 2023 -0400 virtio-net: fix race between set queues and probe BugLink: https://bugs.launchpad.net/bugs/2035400 commit 25266128fe16d5632d43ada34c847d7b8daba539 upstream. A race were found where set_channels could be called after registering but before virtnet_set_queues() in virtnet_probe(). Fixing this by moving the virtnet_set_queues() before netdevice registering. While at it, use _virtnet_set_queues() to avoid holding rtnl as the device is not even registered at that time. Cc: sta...@vger.kernel.org Fixes: a220871be66f ("virtio-net: correctly enable multiqueue") Signed-off-by: Jason Wang <jasow...@redhat.com> Acked-by: Michael S. Tsirkin <m...@redhat.com> Reviewed-by: Xuan Zhuo <xuanz...@linux.alibaba.com> Link: https://lore.kernel.org/r/20230725072049.617289-1-jasow...@redhat.com Signed-off-by: Jakub Kicinski <k...@kernel.org> Signed-off-by: Greg Kroah-Hartman <gre...@linuxfoundation.org> Signed-off-by: Kamal Mostafa <ka...@canonical.com> Signed-off-by: Stefan Bader <stefan.ba...@canonical.com> ``` Investigation into Greg KH's 5.15 branch shows the (unapplied?) followup as: ``` commit 431db3f48c286462ad7453ccdf284f590aafa949 Author: Jason Wang <jasow...@redhat.com> Date: Wed Aug 9 23:12:56 2023 -0400 virtio-net: set queues after driver_ok commit 51b813176f098ff61bd2833f627f5319ead098a5 upstream. Commit 25266128fe16 ("virtio-net: fix race between set queues and probe") tries to fix the race between set queues and probe by calling _virtnet_set_queues() before DRIVER_OK is set. This violates virtio spec. Fixing this by setting queues after virtio_device_ready(). Note that rtnl needs to be held for userspace requests to change the number of queues. So we are serialized in this way. Fixes: 25266128fe16 ("virtio-net: fix race between set queues and probe") Reported-by: Dragos Tatulea <dtatu...@nvidia.com> Acked-by: Michael S. Tsirkin <m...@redhat.com> Signed-off-by: Jason Wang <jasow...@redhat.com> Signed-off-by: David S. Miller <da...@davemloft.net> Signed-off-by: Greg Kroah-Hartman <gre...@linuxfoundation.org> ``` Boot stack trace: ``` [ 28.129660] watchdog: BUG: soft lockup - CPU#1 stuck for 26s! [systemd-udevd:165] [ 28.130265] Modules linked in: crct10dif_pclmul crc32_pclmul ghash_clmulni_intel aesni_intel crypto_simd cryptd virtio_net(+) net_failover virtio_rng failover virtio_blk [ 28.131396] CPU: 1 PID: 165 Comm: systemd-udevd Not tainted 5.15.0-89-generic https://github.com/ubicloud/ubicloud/pull/99-Ubuntu [ 28.131997] Hardware name: Cloud Hypervisor cloud-hypervisor, BIOS 0 [ 28.132479] RIP: 0010:virtnet_send_command+0x10b/0x170 [virtio_net] [ 28.132951] Code: 0b 83 c1 d8 85 c0 0f 88 d2 6e 00 00 48 8b 7b 08 e8 6a 72 c1 d8 84 c0 75 11 eb 56 48 8b 7b 08 e8 6b 5e c1 d8 84 c0 75 17 f3 90 <48> 8b 7b 08 48 8d b5 6c ff ff ff e8 f5 71 c1 d8 48 85 c0 74 dc 48 [ 28.134326] RSP: 0018:ffff9b0c4064f9b8 EFLAGS: 00000246 [ 28.134720] RAX: 0000000000000000 RBX: ffff89dfc0d13980 RCX: 0000000000000a20 [ 28.135252] RDX: 0000000000000000 RSI: ffff9b0c4064f9bc RDI: ffff89dfc7cc00c0 [ 28.135787] RBP: ffff9b0c4064fa50 R08: 0000000000000001 R09: 0000000000000003 [ 28.136316] R10: 0000000000000003 R11: 0000000000000002 R12: ffff9b0c4064f9e0 [ 28.136851] R13: 0000000000000002 R14: 0000000000000004 R15: ffff89dfc0c49400 [ 28.137381] FS: 00007feeba10e8c0(0000) GS:ffff89e0f7d00000(0000) knlGS:0000000000000000 [ 28.137981] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [ 28.138408] CR2: 00007feeba90a0f8 CR3: 0000000100258000 CR4: 0000000000350ee0 [ 28.138940] Call Trace: [ 28.139129] <IRQ> [ 28.139291] ? show_trace_log_lvl+0x1d6/0x2ea [ 28.139627] ? show_trace_log_lvl+0x1d6/0x2ea [ 28.139957] ? _virtnet_set_queues+0xbb/0x100 [virtio_net] [ 28.140369] ? show_regs.part.0+0x23/0x29 [ 28.140672] ? show_regs.cold+0x8/0xd [ 28.140950] ? watchdog_timer_fn+0x1be/0x220 [ 28.141273] ? lockup_detector_update_enable+0x60/0x60 [ 28.141657] ? __hrtimer_run_queues+0x107/0x230 [ 28.142011] ? clockevents_program_event+0xad/0x130 [ 28.142377] ? hrtimer_interrupt+0x101/0x220 [ 28.142698] ? __sysvec_apic_timer_interrupt+0x61/0xe0 [ 28.143084] ? sysvec_apic_timer_interrupt+0x7b/0x90 [ 28.143460] </IRQ> ``` To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/linux/+bug/2045443/+subscriptions -- Mailing list: https://launchpad.net/~kernel-packages Post to : kernel-packages@lists.launchpad.net Unsubscribe : https://launchpad.net/~kernel-packages More help : https://help.launchpad.net/ListHelp
