[Bug 1736390] Re: openvswitch: kernel oops destroying interfaces on i386

[Joseph Salisbury]

I'm still working on the bisect.  It looks like two commits may have
introduced the bug, which is slowing the bisect process.

I found that the following commit causes a kernel trace with rtmsg_ifa
as the EIP:

120645513f55 ("openvswitch: Add eventmask support to CT action.")

Reverting this commit allows the tests to work just fine in v4.12, which
freeze without the revert.  This is allowing me to bisect into newer
kernel versions now.

I'm bisecting further now to identify the commit that is causing the
trace with igmp_group_dropped as the EIP.

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https://bugs.launchpad.net/bugs/1736390

Title:
  openvswitch: kernel oops destroying interfaces on i386

Status in linux package in Ubuntu:
  In Progress
Status in openvswitch package in Ubuntu:
  Invalid
Status in linux source package in Artful:
  In Progress
Status in openvswitch source package in Artful:
  Invalid
Status in linux source package in Bionic:
  In Progress
Status in openvswitch source package in Bionic:
  Invalid

Bug description:
  Reproducable on bionic using the autopkgtest's from openvswitch on
  i386:

  [   41.420568] BUG: unable to handle kernel NULL pointer dereference at   (null)
  [   41.421000] IP: igmp_group_dropped+0x21/0x220
  [   41.421246] *pdpt = 000000001d62c001 *pde = 0000000000000000 

  [   41.421659] Oops: 0000 [#1] SMP
  [   41.421852] Modules linked in: veth openvswitch nf_conntrack_ipv6 nf_nat_ipv6 nf_conntrack_ipv4 nf_defrag_ipv4 nf_nat_ipv4 nf_defrag_ipv6 nf_nat nf_conntrack libcrc32c 9p fscache ppdev kvm_intel kvm 9pnet_virtio irqbypass input_leds joydev 9pnet parport_pc serio_raw parport i2c_piix4 qemu_fw_cfg mac_hid sch_fq_codel ip_tables x_tables autofs4 btrfs xor raid6_pq psmouse virtio_blk virtio_net pata_acpi floppy
  [   41.423855] CPU: 0 PID: 5 Comm: kworker/u2:0 Tainted: G        W       4.13.0-18-generic #21-Ubuntu
  [   41.424355] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.10.2-1ubuntu1 04/01/2014
  [   41.424849] Workqueue: netns cleanup_net
  [   41.425071] task: db8fba80 task.stack: dba10000
  [   41.425346] EIP: igmp_group_dropped+0x21/0x220
  [   41.425656] EFLAGS: 00010202 CPU: 0
  [   41.425864] EAX: 00000000 EBX: dd726360 ECX: dba11e6c EDX: 00000002
  [   41.426335] ESI: 00000000 EDI: dd4db500 EBP: dba11dcc ESP: dba11d94
  [   41.426687]  DS: 007b ES: 007b FS: 00d8 GS: 00e0 SS: 0068
  [   41.426990] CR0: 80050033 CR2: 00000000 CR3: 1e6d6d60 CR4: 000006f0
  [   41.427340] Call Trace:
  [   41.427485]  ? __wake_up+0x36/0x40
  [   41.427680]  ip_mc_down+0x27/0x90
  [   41.427869]  inetdev_event+0x398/0x4e0
  [   41.428082]  ? skb_dequeue+0x5b/0x70
  [   41.428286]  ? wireless_nlevent_flush+0x4c/0x90
  [   41.428541]  notifier_call_chain+0x4e/0x70
  [   41.428772]  raw_notifier_call_chain+0x11/0x20
  [   41.429023]  call_netdevice_notifiers_info+0x2a/0x60
  [   41.429301]  dev_close_many+0x9d/0xe0
  [   41.429509]  rollback_registered_many+0xd7/0x380
  [   41.429768]  unregister_netdevice_many.part.102+0x10/0x80
  [   41.430075]  default_device_exit_batch+0x134/0x160
  [   41.430344]  ? do_wait_intr_irq+0x80/0x80
  [   41.430650]  ops_exit_list.isra.8+0x4d/0x60
  [   41.430886]  cleanup_net+0x18e/0x260
  [   41.431090]  process_one_work+0x1a0/0x390
  [   41.431317]  worker_thread+0x37/0x450
  [   41.431525]  kthread+0xf3/0x110
  [   41.431714]  ? process_one_work+0x390/0x390
  [   41.431941]  ? kthread_create_on_node+0x20/0x20
  [   41.432187]  ret_from_fork+0x19/0x24
  [   41.432382] Code: 90 90 90 90 90 90 90 90 90 90 3e 8d 74 26 00 55 89 e5 57 56 53 89 c3 83 ec 2c 8b 33 65 a1 14 00 00 00 89 45 f0 31 c0 80 7b 4b 00 <8b> 06 8b b8 20 03 00 00 8b 43 04 0f 85 5e 01 00 00 3d e0 00 00
  [   41.433405] EIP: igmp_group_dropped+0x21/0x220 SS:ESP: 0068:dba11d94
  [   41.433750] CR2: 0000000000000000
  [   41.433961] ---[ end trace 595db54cab84070c ]---

  
  system then becomes unresponsive; no further interfaces can be created.

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