__memmove_avx_unaligned segfault

[luisremis]

Thread 71 "main" received signal SIGSEGV, Segmentation fault.
[Switching to Thread 0x7fff4be2d700 (LWP 87175)]
__memmove_avx_unaligned () at ../sysdeps/x86_64/multiarch/memcpy-avx-unaligned.S:238
238 ../sysdeps/x86_64/multiarch/memcpy-avx-unaligned.S: No such file or directory.
(gdb) bt
#0 __memmove_avx_unaligned () at ../sysdeps/x86_64/multiarch/memcpy-avx-unaligned.S:238
#1 0x00007fffeffd17fe in std::__copy_move<false, true, std::random_access_iterator_tag>::__copy_m (__result=, __last=, __first=) at /usr/include/c++/5/bits/stl_algobase.h:384
#2 std::__copy_move_a<false, float const*, float*> (__result=, __last=, __first=) at /usr/include/c++/5/bits/stl_algobase.h:402
#3 std::__copy_move_a2<false, float const*, float*> (__result=0x7ffe05ccb010, __last=, __first=) at /usr/include/c++/5/bits/stl_algobase.h:440
#4 std::copy<float const*, float*> (__result=0x7ffe05ccb010, __last=, __first=) at /usr/include/c++/5/bits/stl_algobase.h:472
#5 std::__uninitialized_copy::__uninit_copy<float const*, float*> (__result=0x7ffe05ccb010, __last=, __first=) at /usr/include/c++/5/bits/stl_uninitialized.h:93
#6 std::uninitialized_copy<float const*, float*> (__result=0x7ffe05ccb010, __last=, __first=) at /usr/include/c++/5/bits/stl_uninitialized.h:126
#7 std::__uninitialized_copy_a<float const*, float*, float> (__result=0x7ffe05ccb010, __last=, __first=) at /usr/include/c++/5/bits/stl_uninitialized.h:281
#8 std::vector<float, std::allocator >::_M_range_insert<float const*> (__last=, __first=, __position=1, this=0x7ffdcc002660) at /usr/include/c++/5/bits/vector.tcc:643
#9 std::vector<float, std::allocator >::_M_insert_dispatch<float const*> (__last=, __first=, __pos=..., this=0x7ffdcc002660) at /usr/include/c++/5/bits/stl_vector.h:1377
#10 std::vector<float, std::allocator >::insert<float const*, void> (__last=, __first=, __position=1, this=0x7ffdcc002660) at /usr/include/c++/5/bits/stl_vector.h:1099
#11 faiss::IndexFlat::add (this=0x7ffdcc002640, n=128, x=) at IndexFlat.cpp:31

I get this error (gdb backtrace) when dealing with small vectors (128 dimensions). I tried using and removing -mavx flag.

Have you encountered this error before? Any clue?

[mdouze]

Hi
This looks like a generic memory corruption. Are you sure that the data pointer you provide on input is large enough?

[luisremis]

Fixed after some code refactoring, indeed, the problem was most likely somewhere else. If I face the problem again, I will try to reproduce it. Thanks for your reply.

[mahmoodn]

@luisremis How did you fix that for small vectors?

[luisremis]

the issue, if I recall correctly, was not related to the vectors sizes, it was something else wrong in my application.

[santiweide]

curious about how you solved it...have met the same core

[itwujian]

me too

[shan-weiqiang]

Do you use std::vector in a multi thread situation? If yes there might be a memeory relocation problem, say: one thread insert a value, causing the vector to enlarge it's size and relocate all it's elements in another memory range. However, another thread stll owns some ref(pointer) to the original memory range of this vector, this might cause the seg fault.

if you reserve the std::vector first and the problem is gone, big chances that this is the reason behind.