test_memopt_fit_a_line fails sometimes

[luotao1]

test_memopt_fit_a_line fails sometimes in TeamCity:

[20:22:10] :	 [Step 1/1] 210/212 Test #212: test_memopt_fit_a_line ..........................***Exception: SegFault  4.48 sec
[20:22:10] :	 [Step 1/1] Hit Cache !!!! cache pool index is 0, var name is tmp_0, cached var name is mean_1.tmp_0@GRAD, var shape is [1L] 
[20:22:10] :	 [Step 1/1] Hit Cache !!!! cache pool index is 0, var name is tmp_2, cached var name is fc_0.b_0@GRAD, var shape is [1L] 
[20:22:10] :	 [Step 1/1] Hit Cache !!!! cache pool index is 0, var name is tmp_3, cached var name is tmp_1, var shape is [1L] 
[20:22:10] :	 [Step 1/1] Hit Cache !!!! cache pool index is 1, var name is y@GRAD, cached var name is square_error_cost_0.tmp_1@GRAD, var shape is [-1L, 1L] 
[20:22:10] :	 [Step 1/1] Hit Cache !!!! cache pool index is 1, var name is fc_0.tmp_1@GRAD, cached var name is square_error_cost_0.tmp_1, var shape is [-1L, 1L] 
[20:22:10] :	 [Step 1/1] Hit Cache !!!! cache pool index is 1, var name is fc_0.tmp_0@GRAD, cached var name is y, var shape is [-1L, 1L] 
[20:22:10] :	 [Step 1/1] Hit Cache !!!! cache pool index is 0, var name is fc_0.b_0@GRAD__nccl_all_reduce__, cached var name is mean_0.tmp_0@GRAD, var shape is [1L] 
[20:22:10] :	 [Step 1/1] Unexpected end of /proc/mounts line `overlay / overlay rw,relatime,lowerdir=/var/local/osd0/docker/overlay2/l/57UUJRTVYZZJSGEPFQTZIQT566:/var/local/osd0/docker/overlay2/l/4GTILHVASP77BF3RBT5SX56QVM:/var/local/osd0/docker/overlay2/l/S2BPF2AZ4RTVXCDUEOJAEHE3OU:/var/local/osd0/docker/overlay2/l/T5XD5VFB7I27WNADWAUUE37YOJ:/var/local/osd0/docker/overlay2/l/X2PYK5OI4RNGYCPU3466VDUQUE:/var/local/osd0/docker/overlay2/l/OWW3JCBEPHGSYF5B5IYGERLVZR:/var/local/osd0/docker/overlay2/l/FYPR6LFDNWX2Y6OAHIZSG4RYDJ:/var/local/osd0/docker/overlay2/l/4NEBWKXEANB'
[20:22:10] :	 [Step 1/1] Unexpected end of /proc/mounts line `7RJYJ5CT67CIWWN:/var/local/osd0/docker/overlay2/l/5J7FEOMK62OCVTOVC5WCHP3GUJ:/var/local/osd0/docker/overlay2/l/QXC4XLCM6NCWHTYT3GXQOM3JL7:/var/local/osd0/docker/overlay2/l/637Q3XP6EF7Z2XM3WFRVKI4D7M:/var/local/osd0/docker/overlay2/l/2CLIZII3MP36UCBCAUYSB6Q2PY:/var/local/osd0/docker/overlay2/l/G7Y4IOQ53HYUYIN4ZXFJCD3XZJ:/var/local/osd0/docker/overlay2/l/U4NJ4AYO2MMWSKYOQIYRGBDP2F:/var/local/osd0/docker/overlay2/l/ZSN3FHLUTFGQLLPDXA3V4YEZUU:/var/local/osd0/docker/overlay2/l/BDENEWPLH4KXFWMYCADAVYVVB2:/var/lo'
[20:22:10] :	 [Step 1/1] Unexpected end of /proc/mounts line `cal/osd0/docker/overlay2/l/CGTT62IBWXDUQYINZ42QNYTON2:/var/local/osd0/docker/overlay2/l/OXGGPNLIB6G4FG4FMPHRKO4KRI:/var/local/osd0/docker/overlay2/l/JAJBAWPNEO3NGU3QBPPLQDFQD6:/var/local/osd0/docker/overlay2/l/CUDU55SQDNKM3JEXH6FQMC4RVA:/var/local/osd0/docker/overlay2/l/HMVNJ6MXZNSTAPURADYRHKS7G2:/var/local/osd0/docker/overlay2/l/6BHH3DD42JPHKCBISOCGZ6O4IU:/var/local/osd0/docker/overlay2/l/HTKK6BPZ2DVGNTVZIC4TNXGMSS:/var/local/osd0/docker/overlay2/l/VDAQQFSLU34AYOONXFMWC3ZBVR:/var/local/osd0/docker/overlay'
[20:22:10] :	 [Step 1/1] Unexpected end of /proc/mounts line `2/l/5WOXCTHWCLFPB2LMPN543BNON3:/var/local/osd0/docker/overlay2/l/5SQBC2PC3M7AXGZONOXQN2ZXEI:/var/local/osd0/docker/overlay2/l/6HPK6CT4QNWRQFB6RHM6DZ3B4T:/var/local/osd0/docker/overlay2/l/AYKRGLPOTKQ3HG2OCQUUNXXJDV:/var/local/osd0/docker/overlay2/l/JMTOMIQFIBBS65D5AQA4AYXZ2J:/var/local/osd0/docker/overlay2/l/AMBVE24EBLT3UNYZN7QKDEXQEX,upperdir=/var/local/osd0/docker/overlay2/fcdab3ea871d6a5179eca7471e27a5477eb18804f7b443b30642e6cc260ce18f/diff,workdir=/var/local/osd0/docker/overlay2/fcdab3ea871d6a5179eca747'
[20:22:10] :	 [Step 1/1] 603.817
[20:22:10] :	 [Step 1/1] 726.9469
[20:22:10] :	 [Step 1/1] 67.22336
[20:22:10] :	 [Step 1/1] 551.19086
[20:22:10] :	 [Step 1/1] 671.1267
[20:22:10] :	 [Step 1/1] 52.88642
[20:22:10] :	 [Step 1/1] 503.82404
[20:22:10] :	 [Step 1/1] *** Aborted at 1520252529 (unix time) try "date -d @1520252529" if you are using GNU date ***
[20:22:10] :	 [Step 1/1] PC: @                0x0 (unknown)
[20:22:10] :	 [Step 1/1] *** SIGSEGV (@0x30) received by PID 14642 (TID 0x7f495ef1e700) from PID 48; stack trace: ***
[20:22:10] :	 [Step 1/1]     @     0x7f495eaf9390 (unknown)
[20:22:10] :	 [Step 1/1]     @     0x7f480fe01078 (unknown)
[20:22:10] :	 [Step 1/1]     @     0x7f480fe05405 ncclCommInitAll
[20:22:10] :	 [Step 1/1]     @     0x7f4919802d04 paddle::operators::NCCLInitOp::RunImpl()
[20:22:10] :	 [Step 1/1]     @     0x7f4918da502a paddle::framework::Executor::Run()
[20:22:10] :	 [Step 1/1]     @     0x7f4918d1c993 _ZZN8pybind1112cpp_function10initializeIZNS0_C4IvN6paddle9framework8ExecutorEIRKNS4_11ProgramDescEPNS4_5ScopeEibbEINS_4nameENS_9is_methodENS_7siblingEEEEMT0_FT_DpT1_EDpRKT2_EUlPS5_S8_SA_ibbE_vISO_S8_SA_ibbEISB_SC_SD_EEEvOSF_PFSE_SH_ESN_ENUlRNS_6detail13function_callEE1_4_FUNESV_
[20:22:10] :	 [Step 1/1]     @     0x7f4918d1a6d4 pybind11::cpp_function::dispatcher()
[20:22:10] :	 [Step 1/1]     @           0x4c37ed PyEval_EvalFrameEx
[20:22:10] :	 [Step 1/1]     @           0x4b9ab6 PyEval_EvalCodeEx
[20:22:10] :	 [Step 1/1]     @           0x4c16e7 PyEval_EvalFrameEx
[20:22:10] :	 [Step 1/1]     @           0x4b9ab6 PyEval_EvalCodeEx
[20:22:10] :	 [Step 1/1]     @           0x4eb30f (unknown)
[20:22:10] :	 [Step 1/1]     @           0x4e5422 PyRun_FileExFlags
[20:22:10] :	 [Step 1/1]     @           0x4e3cd6 PyRun_SimpleFileExFlags
[20:22:10] :	 [Step 1/1]     @           0x493ae2 Py_Main
[20:22:10] :	 [Step 1/1]     @     0x7f495e73e830 __libc_start_main
[20:22:10] :	 [Step 1/1]     @           0x4933e9 _start
[20:22:10] :	 [Step 1/1]     @                0x0 (unknown)
[20:22:10] :	 [Step 1/1]