hi ALL,
I accidentally got following crash stack when I used VCL with hoststack and memfd. But corresponding invalid rx_fifo address (0x2f42e2480) is valid in VPP process and also can be found in /proc/map. That is, shared memfd segment memory is not consistent between hoststack app and VPP.
Generally, VPP allocate/dealloc the memfd segment and then notify hoststack app to attach/detach. But If just after VPP dealloc memfd segment and notify hoststack app, and then VPP allocate same memfd segment at once because of session connected, and then what happened now? Because hoststack app process dealloc message and connected message with diffrent threads, maybe rx_thread_fn just detach the memfd segment and not attach the same memfd segment, then unfortunately worker thread get the connected message.
These are just my guess, maybe I misunderstand.
(gdb) bt
#0 0x00007f7cde21ffbf in raise () from /lib/x86_64-linux-gnu/libpthread.so.0
#1 0x0000000001190a64 in Envoy::SignalAction::sigHandler (sig=11, info=<optimized out>, context=<optimized out>) at source/common/signal/signal_action.cc:73
#2 <signal handler called>
#3 0x00007f7cddc2e85e in vcl_session_connected_handler (wrk=0x7f7ccd4bad00, mp=0x224052f4a) at /home/wanghanlin/vpp-new/src/vcl/vppcom.c:471
#4 0x00007f7cddc37fec in vcl_epoll_wait_handle_mq_event (wrk=0x7f7ccd4bad00, e=0x224052f48, events=0x395000c, num_ev=0x7f7cca49e5e8)
at /home/wanghanlin/vpp-new/src/vcl/vppcom.c:2658
#5 0x00007f7cddc3860d in vcl_epoll_wait_handle_mq (wrk=0x7f7ccd4bad00, mq=0x224042480, events=0x395000c, maxevents=63, wait_for_time=0, num_ev=0x7f7cca49e5e8)
at /home/wanghanlin/vpp-new/src/vcl/vppcom.c:2762
#6 0x00007f7cddc38c74 in vppcom_epoll_wait_eventfd (wrk=0x7f7ccd4bad00, events=0x395000c, maxevents=63, n_evts=0, wait_for_time=0)
at /home/wanghanlin/vpp-new/src/vcl/vppcom.c:2823
#7 0x00007f7cddc393a0 in vppcom_epoll_wait (vep_handle=33554435, events=0x395000c, maxevents=63, wait_for_time=0) at /home/wanghanlin/vpp-new/src/vcl/vppcom.c:2880
#8 0x00007f7cddc5d659 in vls_epoll_wait (ep_vlsh=3, events=0x395000c, maxevents=63, wait_for_time=0) at /home/wanghanlin/vpp-new/src/vcl/vcl_locked.c:895
#9 0x00007f7cdeb4c252 in ldp_epoll_pwait (epfd=67, events=0x3950000, maxevents=64, timeout=32, sigmask=0x0) at /home/wanghanlin/vpp-new/src/vcl/ldp.c:2334
#10 0x00007f7cdeb4c334 in epoll_wait (epfd=67, events=0x3950000, maxevents=64, timeout=32) at /home/wanghanlin/vpp-new/src/vcl/ldp.c:2389
#11 0x0000000000fc9458 in epoll_dispatch ()
#12 0x0000000000fc363c in event_base_loop ()
#13 0x0000000000c09b1c in Envoy::Server::WorkerImpl::threadRoutine (this=0x357d8c0, guard_dog=...) at source/server/worker_impl.cc:104
#14 0x0000000001193485 in std::function<void ()>::operator()() const (this=0x7f7ccd4b8544)
at /usr/lib/gcc/x86_64-linux-gnu/7.4.0/../../../../include/c++/7.4.0/bits/std_function.h:706
#15 Envoy::Thread::ThreadImplPosix::ThreadImplPosix(std::function<void ()>)::$_0::operator()(void*) const (this=<optimized out>, arg=0x2f42e2480)
at source/common/common/posix/thread_impl.cc:33
#16 Envoy::Thread::ThreadImplPosix::ThreadImplPosix(std::function<void ()>)::$_0::__invoke(void*) (arg=0x2f42e2480) at source/common/common/posix/thread_impl.cc:32
#17 0x00007f7cde2164a4 in start_thread () from /lib/x86_64-linux-gnu/libpthread.so.0
#18 0x00007f7cddf58d0f in clone () from /lib/x86_64-linux-gnu/libc.so.6
(gdb) f 3
#3 0x00007f7cddc2e85e in vcl_session_connected_handler (wrk=0x7f7ccd4bad00, mp=0x224052f4a) at /home/wanghanlin/vpp-new/src/vcl/vppcom.c:471
471 rx_fifo->client_session_index = session_index;
(gdb) p rx_fifo
$1 = (svm_fifo_t *) 0x2f42e2480
(gdb) p *rx_fifo
Cannot access memory at address 0x2f42e2480
(gdb)
Regards,
Hanlin
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