Ceph

  <kind>InvalidRead</kind>
  <what>Invalid read of size 4</what>
  <stack>
    <frame>
      <ip>0xBB9F164</ip>
      <obj>/lib/x86_64-linux-gnu/libpthread-2.19.so</obj>
      <fn>__pthread_mutex_cond_lock</fn>
      <dir>/build/buildd/eglibc-2.19/nptl/../nptl</dir>
      <file>pthread_mutex_lock.c</file>
      <line>66</line>
    </frame>
    <frame>
      <ip>0xBB994A3</ip>
      <obj>/lib/x86_64-linux-gnu/libpthread-2.19.so</obj>
      <fn>pthread_cond_wait@@GLIBC_2.3.2</fn>
      <dir>/build/buildd/eglibc-2.19/nptl/../nptl/sysdeps/unix/sysv/linux/x86_64</dir>
      <file>pthread_cond_wait.S</file>
      <line>259</line>
    </frame>
    <frame>
      <ip>0xBD5F3E</ip>
      <obj>/usr/bin/ceph-osd</obj>
      <fn>Pipe::accept()</fn>
      <dir>/srv/autobuild-ceph/gitbuilder.git/build/out~/ceph-10.1.0-571-g3611e39/src/./common</dir>
      <file>Cond.h</file>
      <line>56</line>
    </frame>
    <frame>
      <ip>0xBDAD3E</ip>
      <obj>/usr/bin/ceph-osd</obj>
      <fn>Pipe::reader()</fn>
      <dir>/srv/autobuild-ceph/gitbuilder.git/build/out~/ceph-10.1.0-571-g3611e39/src/msg/simple</dir>
      <file>Pipe.cc</file>
      <line>1499</line>
    </frame>

Can't tell exactly which cond, but my guess is that here the existing Pipe * goes away...

      if (existing->reader_dispatching) {
    /** we need to wait, or we can deadlock if downstream
     *  fast_dispatchers are (naughtily!) waiting on resources
     *  held by somebody trying to make use of the SimpleMessenger lock.
     *  So drop locks, wait, and retry. It just looks like a slow network
     *  to everybody else.
     */
    pipe_lock.Unlock();
    msgr->lock.Unlock();
    existing->notify_on_dispatch_done = true;
    while (existing->reader_dispatching)
      existing->cond.Wait(existing->pipe_lock);
    existing->pipe_lock.Unlock();
    goto retry_existing_lookup;
      }

/a/sage-2016-04-06_19:36:52-rados-wip-sage-testing-distro-basic-smithi/112920