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[Bug 1811515] Re: pyroute2.NetNS don't work properly with concurrency in oslo.privsep

To: yahoo-eng-team@xxxxxxxxxxxxxxxxxxx
From: OpenStack Infra <1811515@xxxxxxxxxxxxxxxxxx>
Date: Thu, 17 Jan 2019 20:06:27 -0000
Reply-to: Bug 1811515 <1811515@xxxxxxxxxxxxxxxxxx>
Sender: bounces@xxxxxxxxxxxxx
Reviewed:  https://review.openstack.org/631275
Committed: https://git.openstack.org/cgit/openstack/neutron/commit/?id=284afcf24f2dfd3af20a803ada79c69205249f25
Submitter: Zuul
Branch:    master

commit 284afcf24f2dfd3af20a803ada79c69205249f25
Author: Slawek Kaplonski <skaplons@xxxxxxxxxx>
Date:   Wed Jan 16 17:13:08 2019 +0100

    Lock privileged.agent.linux.ip_lib functions
    
    It is workaround of bug in pyroute2 library which, when
    running in multithread environment, sometimes have issues
    with NetNS class.
    When NetNS.__init__() is called, it uses os.pipe() function to
    create 2 file descriptors which are used to communicated between
    2 processes.
    In some cases when multiple threads are running it might happen
    that in two instances of NetNS() class there will be same file
    descriptors used and that leads to problems when one thread
    closes file descriptor and second still wants to use it.
    
    With this patch functions which uses instance of pyroute2.NetNS class
    are locked thus there shouldn't be risk of using same file descriptors
    in 2 separate threads.
    
    Co-Authored-By: Rodolfo Alonso Hernandez <ralonsoh@xxxxxxxxxx>
    
    Change-Id: Id5e6f2f8e9c31a7138da9cd6792e9d75845b81c5
    Closes-Bug: #1811515


** Changed in: neutron
       Status: In Progress => Fix Released

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https://bugs.launchpad.net/bugs/1811515

Title:
  pyroute2.NetNS don't work properly with concurrency in oslo.privsep

Status in neutron:
  Fix Released

Bug description:
  It is quite common case that tempest/scenario test jobs are failing because SSH to VM through floating IP fails.
  It looks that in many (I'm not sure if all) case there are some errors from pyroute2 library in L3 agent logs and that looks like reason of many of such SSH failures.

  Example of such fail in logs is e.g. in
  http://logs.openstack.org/43/628943/2/check/tempest-
  full/b955419/controller/logs/screen-q-l3.txt.gz#_Jan_11_23_41_31_955036

  Stacktrace looks like below:

  Jan 11 23:41:31.954562 ubuntu-bionic-rax-iad-0001661199 neutron-l3-agent[5600]: ERROR pyroute2.netns.nslink [-] forced shutdown procedure, clean up netns manually
  Jan 11 23:41:31.955036 ubuntu-bionic-rax-iad-0001661199 neutron-l3-agent[5600]: DEBUG oslo.privsep.daemon [-] privsep: Exception during request[139718939505360]: [Errno 9] Bad file descriptor {{(pid=6501) _process_cmd /usr/local/lib/python2.7/dist-packages/oslo_privsep/daemon.py:452}}
  Jan 11 23:41:31.955036 ubuntu-bionic-rax-iad-0001661199 neutron-l3-agent[5600]: Traceback (most recent call last):
  Jan 11 23:41:31.955036 ubuntu-bionic-rax-iad-0001661199 neutron-l3-agent[5600]:   File "/usr/local/lib/python2.7/dist-packages/oslo_privsep/daemon.py", line 447, in _process_cmd
  Jan 11 23:41:31.955036 ubuntu-bionic-rax-iad-0001661199 neutron-l3-agent[5600]:     ret = func(*f_args, **f_kwargs)
  Jan 11 23:41:31.955036 ubuntu-bionic-rax-iad-0001661199 neutron-l3-agent[5600]:   File "/usr/local/lib/python2.7/dist-packages/oslo_privsep/priv_context.py", line 216, in _wrap
  Jan 11 23:41:31.955036 ubuntu-bionic-rax-iad-0001661199 neutron-l3-agent[5600]:     return func(*args, **kwargs)
  Jan 11 23:41:31.955036 ubuntu-bionic-rax-iad-0001661199 neutron-l3-agent[5600]:   File "/opt/stack/neutron/neutron/privileged/agent/linux/ip_lib.py", line 244, in add_ip_address
  Jan 11 23:41:31.955036 ubuntu-bionic-rax-iad-0001661199 neutron-l3-agent[5600]:     scope=_get_scope_name(scope))
  Jan 11 23:41:31.955036 ubuntu-bionic-rax-iad-0001661199 neutron-l3-agent[5600]:   File "/opt/stack/neutron/neutron/privileged/agent/linux/ip_lib.py", line 220, in _run_iproute_addr
  Jan 11 23:41:31.955036 ubuntu-bionic-rax-iad-0001661199 neutron-l3-agent[5600]:     with _get_iproute(namespace) as ip:
  Jan 11 23:41:31.955036 ubuntu-bionic-rax-iad-0001661199 neutron-l3-agent[5600]:   File "/opt/stack/neutron/neutron/privileged/agent/linux/ip_lib.py", line 169, in _get_iproute
  Jan 11 23:41:31.955036 ubuntu-bionic-rax-iad-0001661199 neutron-l3-agent[5600]:     return pyroute2.NetNS(namespace, flags=0)
  Jan 11 23:41:31.955036 ubuntu-bionic-rax-iad-0001661199 neutron-l3-agent[5600]:   File "/usr/local/lib/python2.7/dist-packages/pyroute2/netns/nslink.py", line 170, in __init__
  Jan 11 23:41:31.955036 ubuntu-bionic-rax-iad-0001661199 neutron-l3-agent[5600]:     super(NetNS, self).__init__(trnsp_in, trnsp_out)
  Jan 11 23:41:31.955036 ubuntu-bionic-rax-iad-0001661199 neutron-l3-agent[5600]:   File "/usr/local/lib/python2.7/dist-packages/pyroute2/iproute/linux.py", line 127, in __init__
  Jan 11 23:41:31.955036 ubuntu-bionic-rax-iad-0001661199 neutron-l3-agent[5600]:     super(RTNL_API, self).__init__(*argv, **kwarg)
  Jan 11 23:41:31.955036 ubuntu-bionic-rax-iad-0001661199 neutron-l3-agent[5600]:   File "/usr/local/lib/python2.7/dist-packages/pyroute2/remote/__init__.py", line 196, in __init__
  Jan 11 23:41:31.955036 ubuntu-bionic-rax-iad-0001661199 neutron-l3-agent[5600]:     init = self.trnsp_in.recv_cmd()
  Jan 11 23:41:31.955036 ubuntu-bionic-rax-iad-0001661199 neutron-l3-agent[5600]:   File "/usr/local/lib/python2.7/dist-packages/pyroute2/remote/__init__.py", line 77, in recv_cmd
  Jan 11 23:41:31.955036 ubuntu-bionic-rax-iad-0001661199 neutron-l3-agent[5600]:     ret = self.__recv()
  Jan 11 23:41:31.955036 ubuntu-bionic-rax-iad-0001661199 neutron-l3-agent[5600]:   File "/usr/local/lib/python2.7/dist-packages/pyroute2/remote/__init__.py", line 51, in __recv
  Jan 11 23:41:31.955036 ubuntu-bionic-rax-iad-0001661199 neutron-l3-agent[5600]:     dump.write(self.file_obj.read(length - 8))
  Jan 11 23:41:31.955036 ubuntu-bionic-rax-iad-0001661199 neutron-l3-agent[5600]: OSError: [Errno 9] Bad file descriptor
  Jan 11 23:41:31.957344 ubuntu-bionic-rax-iad-0001661199 neutron-l3-agent[5600]: DEBUG oslo.privsep.daemon [-] privsep: reply[139718939505360]: (5, 'exceptions.OSError', (9, 'Bad file descriptor')) {{(pid=6501) _call_back /usr/local/lib/python2.7/dist-packages/oslo_privsep/daemon.py:473}}
  Jan 11 23:41:31.966453 ubuntu-bionic-rax-iad-0001661199 neutron-l3-agent[5600]: ERROR neutron.agent.l3.router_info [-] [Errno 88] Socket operation on non-socket: error: [Errno 88] Socket operation on non-socket
  Jan 11 23:41:31.966453 ubuntu-bionic-rax-iad-0001661199 neutron-l3-agent[5600]: ERROR neutron.agent.l3.router_info Traceback (most recent call last):
  Jan 11 23:41:31.966453 ubuntu-bionic-rax-iad-0001661199 neutron-l3-agent[5600]: ERROR neutron.agent.l3.router_info   File "/opt/stack/neutron/neutron/common/utils.py", line 158, in call
  Jan 11 23:41:31.966453 ubuntu-bionic-rax-iad-0001661199 neutron-l3-agent[5600]: ERROR neutron.agent.l3.router_info     return func(*args, **kwargs)
  Jan 11 23:41:31.966453 ubuntu-bionic-rax-iad-0001661199 neutron-l3-agent[5600]: ERROR neutron.agent.l3.router_info   File "/opt/stack/neutron/neutron/agent/l3/router_info.py", line 1175, in process
  Jan 11 23:41:31.966453 ubuntu-bionic-rax-iad-0001661199 neutron-l3-agent[5600]: ERROR neutron.agent.l3.router_info     self._process_internal_ports()
  Jan 11 23:41:31.966453 ubuntu-bionic-rax-iad-0001661199 neutron-l3-agent[5600]: ERROR neutron.agent.l3.router_info   File "/opt/stack/neutron/neutron/agent/l3/router_info.py", line 560, in _process_internal_ports
  Jan 11 23:41:31.966453 ubuntu-bionic-rax-iad-0001661199 neutron-l3-agent[5600]: ERROR neutron.agent.l3.router_info     self.internal_network_added(p)
  Jan 11 23:41:31.966453 ubuntu-bionic-rax-iad-0001661199 neutron-l3-agent[5600]: ERROR neutron.agent.l3.router_info   File "/opt/stack/neutron/neutron/agent/l3/router_info.py", line 477, in internal_network_added
  Jan 11 23:41:31.966453 ubuntu-bionic-rax-iad-0001661199 neutron-l3-agent[5600]: ERROR neutron.agent.l3.router_info     mtu=port.get('mtu'))
  Jan 11 23:41:31.966453 ubuntu-bionic-rax-iad-0001661199 neutron-l3-agent[5600]: ERROR neutron.agent.l3.router_info   File "/opt/stack/neutron/neutron/agent/l3/router_info.py", line 452, in _internal_network_added
  Jan 11 23:41:31.966453 ubuntu-bionic-rax-iad-0001661199 neutron-l3-agent[5600]: ERROR neutron.agent.l3.router_info     prefix=prefix, mtu=mtu)
  Jan 11 23:41:31.966453 ubuntu-bionic-rax-iad-0001661199 neutron-l3-agent[5600]: ERROR neutron.agent.l3.router_info   File "/opt/stack/neutron/neutron/agent/linux/interface.py", line 276, in plug
  Jan 11 23:41:31.966453 ubuntu-bionic-rax-iad-0001661199 neutron-l3-agent[5600]: ERROR neutron.agent.l3.router_info     bridge, namespace, prefix, mtu)
  Jan 11 23:41:31.966453 ubuntu-bionic-rax-iad-0001661199 neutron-l3-agent[5600]: ERROR neutron.agent.l3.router_info   File "/opt/stack/neutron/neutron/agent/linux/interface.py", line 359, in plug_new
  Jan 11 23:41:31.966453 ubuntu-bionic-rax-iad-0001661199 neutron-l3-agent[5600]: ERROR neutron.agent.l3.router_info     self.check_bridge_exists(bridge)
  Jan 11 23:41:31.966453 ubuntu-bionic-rax-iad-0001661199 neutron-l3-agent[5600]: ERROR neutron.agent.l3.router_info   File "/opt/stack/neutron/neutron/agent/linux/interface.py", line 233, in check_bridge_exists
  Jan 11 23:41:31.966453 ubuntu-bionic-rax-iad-0001661199 neutron-l3-agent[5600]: ERROR neutron.agent.l3.router_info     if not ip_lib.device_exists(bridge):
  Jan 11 23:41:31.966453 ubuntu-bionic-rax-iad-0001661199 neutron-l3-agent[5600]: ERROR neutron.agent.l3.router_info   File "/opt/stack/neutron/neutron/agent/linux/ip_lib.py", line 799, in device_exists
  Jan 11 23:41:31.966453 ubuntu-bionic-rax-iad-0001661199 neutron-l3-agent[5600]: ERROR neutron.agent.l3.router_info     return IPDevice(device_name, namespace=namespace).exists()
  Jan 11 23:41:31.966453 ubuntu-bionic-rax-iad-0001661199 neutron-l3-agent[5600]: ERROR neutron.agent.l3.router_info   File "/opt/stack/neutron/neutron/agent/linux/ip_lib.py", line 305, in exists
  Jan 11 23:41:31.966453 ubuntu-bionic-rax-iad-0001661199 neutron-l3-agent[5600]: ERROR neutron.agent.l3.router_info     return privileged.interface_exists(self.name, self.namespace)
  Jan 11 23:41:31.966453 ubuntu-bionic-rax-iad-0001661199 neutron-l3-agent[5600]: ERROR neutron.agent.l3.router_info   File "/usr/local/lib/python2.7/dist-packages/oslo_privsep/priv_context.py", line 214, in _wrap
  Jan 11 23:41:31.966453 ubuntu-bionic-rax-iad-0001661199 neutron-l3-agent[5600]: ERROR neutron.agent.l3.router_info     return self.channel.remote_call(name, args, kwargs)
  Jan 11 23:41:31.966453 ubuntu-bionic-rax-iad-0001661199 neutron-l3-agent[5600]: ERROR neutron.agent.l3.router_info   File "/usr/local/lib/python2.7/dist-packages/oslo_privsep/daemon.py", line 204, in remote_call
  Jan 11 23:41:31.966453 ubuntu-bionic-rax-iad-0001661199 neutron-l3-agent[5600]: ERROR neutron.agent.l3.router_info     raise exc_type(*result[2])
  Jan 11 23:41:31.966453 ubuntu-bionic-rax-iad-0001661199 neutron-l3-agent[5600]: ERROR neutron.agent.l3.router_info error: [Errno 88] Socket operation on non-socket
  Jan 11 23:41:31.966453 ubuntu-bionic-rax-iad-0001661199 neutron-l3-agent[5600]: ERROR neutron.agent.l3.router_info 
  Jan 11 23:41:31.973050 ubuntu-bionic-rax-iad-0001661199 neutron-l3-agent[5600]: ERROR neutron.agent.l3.agent [-] Failed to process compatible router: a4f60f08-8daa-4361-8b85-1a9b770ee03c: error: [Errno 88] Socket operation on non-socket
  Jan 11 23:41:31.973050 ubuntu-bionic-rax-iad-0001661199 neutron-l3-agent[5600]: ERROR neutron.agent.l3.agent Traceback (most recent call last):
  Jan 11 23:41:31.973050 ubuntu-bionic-rax-iad-0001661199 neutron-l3-agent[5600]: ERROR neutron.agent.l3.agent   File "/opt/stack/neutron/neutron/agent/l3/agent.py", line 623, in _process_routers_if_compatible
  Jan 11 23:41:31.973050 ubuntu-bionic-rax-iad-0001661199 neutron-l3-agent[5600]: ERROR neutron.agent.l3.agent     self._process_router_if_compatible(router)
  Jan 11 23:41:31.973050 ubuntu-bionic-rax-iad-0001661199 neutron-l3-agent[5600]: ERROR neutron.agent.l3.agent   File "/opt/stack/neutron/neutron/agent/l3/agent.py", line 498, in _process_router_if_compatible
  Jan 11 23:41:31.973050 ubuntu-bionic-rax-iad-0001661199 neutron-l3-agent[5600]: ERROR neutron.agent.l3.agent     self._process_added_router(router)
  Jan 11 23:41:31.973050 ubuntu-bionic-rax-iad-0001661199 neutron-l3-agent[5600]: ERROR neutron.agent.l3.agent   File "/opt/stack/neutron/neutron/agent/l3/agent.py", line 506, in _process_added_router
  Jan 11 23:41:31.973050 ubuntu-bionic-rax-iad-0001661199 neutron-l3-agent[5600]: ERROR neutron.agent.l3.agent     ri.process()
  Jan 11 23:41:31.973050 ubuntu-bionic-rax-iad-0001661199 neutron-l3-agent[5600]: ERROR neutron.agent.l3.agent   File "/opt/stack/neutron/neutron/common/utils.py", line 161, in call
  Jan 11 23:41:31.973050 ubuntu-bionic-rax-iad-0001661199 neutron-l3-agent[5600]: ERROR neutron.agent.l3.agent     self.logger(e)
  Jan 11 23:41:31.973050 ubuntu-bionic-rax-iad-0001661199 neutron-l3-agent[5600]: ERROR neutron.agent.l3.agent   File "/usr/local/lib/python2.7/dist-packages/oslo_utils/excutils.py", line 220, in __exit__
  Jan 11 23:41:31.973050 ubuntu-bionic-rax-iad-0001661199 neutron-l3-agent[5600]: ERROR neutron.agent.l3.agent     self.force_reraise()
  Jan 11 23:41:31.973050 ubuntu-bionic-rax-iad-0001661199 neutron-l3-agent[5600]: ERROR neutron.agent.l3.agent   File "/usr/local/lib/python2.7/dist-packages/oslo_utils/excutils.py", line 196, in force_reraise
  Jan 11 23:41:31.973050 ubuntu-bionic-rax-iad-0001661199 neutron-l3-agent[5600]: ERROR neutron.agent.l3.agent     six.reraise(self.type_, self.value, self.tb)
  Jan 11 23:41:31.973050 ubuntu-bionic-rax-iad-0001661199 neutron-l3-agent[5600]: ERROR neutron.agent.l3.agent   File "/opt/stack/neutron/neutron/common/utils.py", line 158, in call
  Jan 11 23:41:31.973050 ubuntu-bionic-rax-iad-0001661199 neutron-l3-agent[5600]: ERROR neutron.agent.l3.agent     return func(*args, **kwargs)
  Jan 11 23:41:31.973050 ubuntu-bionic-rax-iad-0001661199 neutron-l3-agent[5600]: ERROR neutron.agent.l3.agent   File "/opt/stack/neutron/neutron/agent/l3/router_info.py", line 1175, in process
  Jan 11 23:41:31.973050 ubuntu-bionic-rax-iad-0001661199 neutron-l3-agent[5600]: ERROR neutron.agent.l3.agent     self._process_internal_ports()
  Jan 11 23:41:31.973050 ubuntu-bionic-rax-iad-0001661199 neutron-l3-agent[5600]: ERROR neutron.agent.l3.agent   File "/opt/stack/neutron/neutron/agent/l3/router_info.py", line 560, in _process_internal_ports
  Jan 11 23:41:31.973050 ubuntu-bionic-rax-iad-0001661199 neutron-l3-agent[5600]: ERROR neutron.agent.l3.agent     self.internal_network_added(p)
  Jan 11 23:41:31.973050 ubuntu-bionic-rax-iad-0001661199 neutron-l3-agent[5600]: ERROR neutron.agent.l3.agent   File "/opt/stack/neutron/neutron/agent/l3/router_info.py", line 477, in internal_network_added
  Jan 11 23:41:31.973050 ubuntu-bionic-rax-iad-0001661199 neutron-l3-agent[5600]: ERROR neutron.agent.l3.agent     mtu=port.get('mtu'))
  Jan 11 23:41:31.973050 ubuntu-bionic-rax-iad-0001661199 neutron-l3-agent[5600]: ERROR neutron.agent.l3.agent   File "/opt/stack/neutron/neutron/agent/l3/router_info.py", line 452, in _internal_network_added
  Jan 11 23:41:31.973050 ubuntu-bionic-rax-iad-0001661199 neutron-l3-agent[5600]: ERROR neutron.agent.l3.agent     prefix=prefix, mtu=mtu)
  Jan 11 23:41:31.973050 ubuntu-bionic-rax-iad-0001661199 neutron-l3-agent[5600]: ERROR neutron.agent.l3.agent   File "/opt/stack/neutron/neutron/agent/linux/interface.py", line 276, in plug
  Jan 11 23:41:31.973050 ubuntu-bionic-rax-iad-0001661199 neutron-l3-agent[5600]: ERROR neutron.agent.l3.agent     bridge, namespace, prefix, mtu)
  Jan 11 23:41:31.973050 ubuntu-bionic-rax-iad-0001661199 neutron-l3-agent[5600]: ERROR neutron.agent.l3.agent   File "/opt/stack/neutron/neutron/agent/linux/interface.py", line 359, in plug_new
  Jan 11 23:41:31.973050 ubuntu-bionic-rax-iad-0001661199 neutron-l3-agent[5600]: ERROR neutron.agent.l3.agent     self.check_bridge_exists(bridge)
  Jan 11 23:41:31.973050 ubuntu-bionic-rax-iad-0001661199 neutron-l3-agent[5600]: ERROR neutron.agent.l3.agent   File "/opt/stack/neutron/neutron/agent/linux/interface.py", line 233, in check_bridge_exists
  Jan 11 23:41:31.973050 ubuntu-bionic-rax-iad-0001661199 neutron-l3-agent[5600]: ERROR neutron.agent.l3.agent     if not ip_lib.device_exists(bridge):
  Jan 11 23:41:31.973050 ubuntu-bionic-rax-iad-0001661199 neutron-l3-agent[5600]: ERROR neutron.agent.l3.agent   File "/opt/stack/neutron/neutron/agent/linux/ip_lib.py", line 799, in device_exists
  Jan 11 23:41:31.973050 ubuntu-bionic-rax-iad-0001661199 neutron-l3-agent[5600]: ERROR neutron.agent.l3.agent     return IPDevice(device_name, namespace=namespace).exists()
  Jan 11 23:41:31.973050 ubuntu-bionic-rax-iad-0001661199 neutron-l3-agent[5600]: ERROR neutron.agent.l3.agent   File "/opt/stack/neutron/neutron/agent/linux/ip_lib.py", line 305, in exists
  Jan 11 23:41:31.973050 ubuntu-bionic-rax-iad-0001661199 neutron-l3-agent[5600]: ERROR neutron.agent.l3.agent     return privileged.interface_exists(self.name, self.namespace)
  Jan 11 23:41:31.973050 ubuntu-bionic-rax-iad-0001661199 neutron-l3-agent[5600]: ERROR neutron.agent.l3.agent   File "/usr/local/lib/python2.7/dist-packages/oslo_privsep/priv_context.py", line 214, in _wrap
  Jan 11 23:41:31.973050 ubuntu-bionic-rax-iad-0001661199 neutron-l3-agent[5600]: ERROR neutron.agent.l3.agent     return self.channel.remote_call(name, args, kwargs)
  Jan 11 23:41:31.973050 ubuntu-bionic-rax-iad-0001661199 neutron-l3-agent[5600]: ERROR neutron.agent.l3.agent   File "/usr/local/lib/python2.7/dist-packages/oslo_privsep/daemon.py", line 204, in remote_call
  Jan 11 23:41:31.973050 ubuntu-bionic-rax-iad-0001661199 neutron-l3-agent[5600]: ERROR neutron.agent.l3.agent     raise exc_type(*result[2])
  Jan 11 23:41:31.977173 ubuntu-bionic-rax-iad-0001661199 neutron-l3-agent[5600]: ERROR neutron.agent.l3.agent error: [Errno 88] Socket operation on non-socket

  
  It don't look like related to recent Oslo.privsep update as according to logstash it happened also before oslo.privsep 1.31.0.
  I don't know since when it is like that but looks that recently it started to happens more often than in the past.
  It looks for me like some race between threads/workers that one tries to read (or write sometimes) something from opened file descriptor but something else already closed it.

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References

[Bug 1811515] [NEW] SSH to FIP fails in CI jobs
From: Slawek Kaplonski, 2019-01-12