Hi, On 2026-08-06 17:28, Paul Gevers wrote: > Source: faiss > Version: 1.13.2-1 > Severity: serious > X-Debbugs-CC: [email protected] [email protected] > Tags: sid forky > User: [email protected] > Usertags: needs-update > Control: affects -1 src:gcc-defaults > User: [email protected] > Usertags: riscv64 > > Dear maintainer(s), > > With a recent upload of gcc-defaults the autopkgtest of faiss fails in > testing when that autopkgtest is run with the binary packages of > gcc-defaults from unstable. It passes when run with only packages from > testing. In tabular form: > > pass fail > gcc-defaults from testing 1.233 > faiss from testing 1.13.2-1 > all others from testing from testing > > I copied some of the output at the bottom of this report. > > Currently this regression is blocking the migration of gcc-defaults to > testing [1]. Of course, gcc-defaults shouldn't just break your autopkgtest > (or even worse, your package), but it seems to me that the change in > gcc-defaults was intended and your package needs to update to the new > situation. > > If this is a real problem in your package (and not only in your > autopkgtest), the right binary package(s) from gcc-defaults should really > add a versioned Breaks on the unfixed version of (one of your) package(s). > Note: the Breaks is nice even if the issue is only in the autopkgtest as it > helps the migration software to figure out the right versions to combine in > the tests. > > More information about this bug and the reason for filing it can be found on > https://wiki.debian.org/ContinuousIntegration/RegressionEmailInformation > > Paul > > [1] https://qa.debian.org/excuses.php?package=gcc-defaults > > https://ci.debian.net/data/autopkgtest/testing/riscv64/f/faiss/74133117/log.gz > > 7572s test 119 > 7572s Start 119: HNSWTest.TEST_search_from_candidate_unbounded > 7572s 7572s 119: Test command: > /tmp/autopkgtest.Eu4j7u/autopkgtest_tmp/tests/build/faiss_test > "--gtest_filter=HNSWTest.TEST_search_from_candidate_unbounded" > "--gtest_also_run_disabled_tests" > 7572s 119: Working Directory: > /tmp/autopkgtest.Eu4j7u/autopkgtest_tmp/tests/build > 7572s 119: Test timeout computed to be: 10000000 > 7572s 119: WARNING clustering 1000 points to 40 centroids: please provide at > least 1560 training points > 7572s 119: Running main() from ./googletest/src/gtest_main.cc > 7572s 119: Note: Google Test filter = > HNSWTest.TEST_search_from_candidate_unbounded > 7572s 119: [==========] Running 1 test from 1 test suite. > 7572s 119: [----------] Global test environment set-up. > 7572s 119: [----------] 1 test from HNSWTest > 7572s 119: [ RUN ] HNSWTest.TEST_search_from_candidate_unbounded > 7572s 119/133 Test #119: HNSWTest.TEST_search_from_candidate_unbounded > .....................***Exception: SegFault 0.14 sec > > > 7577s 7577s 99% tests passed, 1 tests failed out of 133 > 7577s 7577s Total Test time (real) = 444.00 sec > 7577s 7577s The following tests FAILED: > 7577s 119 - HNSWTest.TEST_search_from_candidate_unbounded (SEGFAULT) > 7577s Errors while running CTest
While the test seemed to fail reliably on the debci host, I wasn't able to reproduce the problem. After giving it back, it succeeded [1] with gcc-16, so it's not a regression, but rather an unreliable test. I also noticed that the autopkgtest time varies quite a lot (up to a factor 3 for a given debci runner), so I guess the high level of concurrent autopkgtests job following the gcc-default upload explains that. I have therefore tried to reproduce the issue under high load, and I have been successful. Here is the corresponding backtrace: | GNU gdb (Debian 17.2-1+b1) 17.2 | Copyright (C) 2025 Free Software Foundation, Inc. | License GPLv3+: GNU GPL version 3 or later <http://gnu.org/licenses/gpl.html> | This is free software: you are free to change and redistribute it. | There is NO WARRANTY, to the extent permitted by law. | Type "show copying" and "show warranty" for details. | This GDB was configured as "riscv64-linux-gnu". | Type "show configuration" for configuration details. | For bug reporting instructions, please see: | <https://www.gnu.org/software/gdb/bugs/>. | Find the GDB manual and other documentation resources online at: | <http://www.gnu.org/software/gdb/documentation/>. | | For help, type "help". | Type "apropos word" to search for commands related to "word"... | Reading symbols from /home/aurel32/faiss/autopkgtest_tmp/tests/build/faiss_test... | (No debugging symbols found in /home/aurel32/faiss/autopkgtest_tmp/tests/build/faiss_test) | [New LWP 16849] | [New LWP 16848] | [New LWP 16850] | [New LWP 16851] | [Thread debugging using libthread_db enabled] | Using host libthread_db library "/usr/lib/riscv64-linux-gnu/libthread_db.so.1". | Core was generated by `/home/aurel32/faiss/autopkgtest_tmp/tests/build/faiss_test --gtest_filter=HNSWT'. | Program terminated with signal SIGSEGV, Segmentation fault. | #0 0x0000002ad7aeb6c2 in faiss::fvec_L2sqr_batch_4(float const*, float const*, float const*, float const*, float const*, unsigned long, float&, float&, float&, float&) () | [Current thread is 1 (Thread 0x3faf4420e0 (LWP 16849))] | (gdb) bt | #0 0x0000002ad7aeb6c2 in faiss::fvec_L2sqr_batch_4(float const*, float const*, float const*, float const*, float const*, unsigned long, float&, float&, float&, float&) () | #1 0x0000002ad7823f0c in faiss::(anonymous namespace)::FlatL2Dis::distances_batch_4(long, long, long, long, float&, float&, float&, float&) () | #2 0x0000002ad79014f6 in faiss::search_neighbors_to_add(faiss::HNSW&, faiss::DistanceComputer&, std::priority_queue<faiss::HNSW::NodeDistCloser, std::vector<faiss::HNSW::NodeDistCloser, std::allocator<faiss::HNSW::NodeDistCloser> >, std:: | less<faiss::HNSW::NodeDistCloser> >&, int, float, int, faiss::VisitedTable&, bool) () | #3 0x0000002ad7902f94 in faiss::HNSW::add_links_starting_from(faiss::DistanceComputer&, int, int, float, int, omp_lock_t*, faiss::VisitedTable&, bool) () | #4 0x0000002ad79033d2 in faiss::HNSW::add_with_locks(faiss::DistanceComputer&, int, int, std::vector<omp_lock_t, std::allocator<omp_lock_t> >&, faiss::VisitedTable&, bool) () | #5 0x0000002ad78498b0 in faiss::(anonymous namespace)::hnsw_add_vertices(faiss::IndexHNSW&, unsigned long, unsigned long, float const*, bool, bool) [clone ._omp_fn.0] () | #6 0x0000003fafeeff3e in ?? () from /usr/lib/riscv64-linux-gnu/libgomp.so.1 | #7 0x0000003faf64e330 in ?? () from /usr/lib/riscv64-linux-gnu/libc.so.6 | #8 0x0000003faf69b670 in ?? () from /usr/lib/riscv64-linux-gnu/libc.so.6 | (gdb) disassemble | Dump of assembler code for function _ZN5faiss18fvec_L2sqr_batch_4EPKfS1_S1_S1_S1_mRfS2_S2_S2_: | 0x0000002ad7aeb59e <+0>: ld t2,0(sp) | 0x0000002ad7aeb5a0 <+2>: beqz a5,0x2ad7aeb7e0 <_ZN5faiss18fvec_L2sqr_batch_4EPKfS1_S1_S1_S1_mRfS2_S2_S2_+578> | 0x0000002ad7aeb5a4 <+6>: slli a5,a5,0x2 | 0x0000002ad7aeb5a6 <+8>: addi t3,a5,-4 | 0x0000002ad7aeb5aa <+12>: fmv.w.x fa5,zero | 0x0000002ad7aeb5ae <+16>: srli t0,t3,0x2 | 0x0000002ad7aeb5b2 <+20>: addi t1,t0,1 | 0x0000002ad7aeb5b6 <+24>: andi t5,t1,3 | 0x0000002ad7aeb5ba <+28>: fmv.s ft5,fa5 | 0x0000002ad7aeb5be <+32>: fmv.s ft3,fa5 | 0x0000002ad7aeb5c2 <+36>: fmv.s fa4,fa5 | 0x0000002ad7aeb5c6 <+40>: li t1,0 | 0x0000002ad7aeb5c8 <+42>: beqz t5,0x2ad7aeb6a6 <_ZN5faiss18fvec_L2sqr_batch_4EPKfS1_S1_S1_S1_mRfS2_S2_S2_+264> | 0x0000002ad7aeb5cc <+46>: li t4,1 | 0x0000002ad7aeb5ce <+48>: beq t5,t4,0x2ad7aeb658 <_ZN5faiss18fvec_L2sqr_batch_4EPKfS1_S1_S1_S1_mRfS2_S2_S2_+186> | 0x0000002ad7aeb5d2 <+52>: li t6,2 | 0x0000002ad7aeb5d4 <+54>: beq t5,t6,0x2ad7aeb60e <_ZN5faiss18fvec_L2sqr_batch_4EPKfS1_S1_S1_S1_mRfS2_S2_S2_+112> | 0x0000002ad7aeb5d8 <+58>: flw fa3,0(a0) | 0x0000002ad7aeb5dc <+62>: flw fa4,0(a1) | 0x0000002ad7aeb5e0 <+66>: flw ft1,0(a2) | 0x0000002ad7aeb5e4 <+70>: flw ft0,0(a3) | 0x0000002ad7aeb5e8 <+74>: flw fa2,0(a4) | 0x0000002ad7aeb5ec <+78>: fsub.s ft2,fa3,fa4 | 0x0000002ad7aeb5f0 <+82>: fsub.s ft3,fa3,ft1 | 0x0000002ad7aeb5f4 <+86>: fsub.s ft4,fa3,ft0 | 0x0000002ad7aeb5f8 <+90>: fsub.s ft6,fa3,fa2 | 0x0000002ad7aeb5fc <+94>: li t1,4 | 0x0000002ad7aeb5fe <+96>: fmadd.s fa4,ft2,ft2,fa5 | 0x0000002ad7aeb602 <+100>: fmadd.s ft3,ft3,ft3,fa5 | 0x0000002ad7aeb606 <+104>: fmadd.s ft5,ft4,ft4,fa5 | 0x0000002ad7aeb60a <+108>: fmadd.s fa5,ft6,ft6,fa5 | 0x0000002ad7aeb60e <+112>: add t0,a0,t1 | 0x0000002ad7aeb612 <+116>: add t3,a1,t1 | 0x0000002ad7aeb616 <+120>: add t5,a2,t1 | 0x0000002ad7aeb61a <+124>: add t4,a3,t1 | 0x0000002ad7aeb61e <+128>: add t6,a4,t1 | 0x0000002ad7aeb622 <+132>: flw ft7,0(t0) | 0x0000002ad7aeb626 <+136>: flw fa0,0(t3) | 0x0000002ad7aeb62a <+140>: flw fa1,0(t5) | 0x0000002ad7aeb62e <+144>: flw fa6,0(t4) | 0x0000002ad7aeb632 <+148>: flw fa7,0(t6) | 0x0000002ad7aeb636 <+152>: fsub.s ft8,ft7,fa0 | 0x0000002ad7aeb63a <+156>: fsub.s ft9,ft7,fa1 | 0x0000002ad7aeb63e <+160>: fsub.s ft10,ft7,fa6 | 0x0000002ad7aeb642 <+164>: fsub.s ft11,ft7,fa7 | 0x0000002ad7aeb646 <+168>: addi t1,t1,4 | 0x0000002ad7aeb648 <+170>: fmadd.s fa4,ft8,ft8,fa4 | 0x0000002ad7aeb64c <+174>: fmadd.s ft3,ft9,ft9,ft3 | 0x0000002ad7aeb650 <+178>: fmadd.s ft5,ft10,ft10,ft5 | 0x0000002ad7aeb654 <+182>: fmadd.s fa5,ft11,ft11,fa5 | 0x0000002ad7aeb658 <+186>: add t0,a0,t1 | 0x0000002ad7aeb65c <+190>: add t3,a1,t1 | 0x0000002ad7aeb660 <+194>: add t5,a2,t1 | 0x0000002ad7aeb664 <+198>: add t4,a3,t1 | 0x0000002ad7aeb668 <+202>: add t6,a4,t1 | 0x0000002ad7aeb66c <+206>: flw fa3,0(t0) | 0x0000002ad7aeb670 <+210>: flw ft1,0(t3) | 0x0000002ad7aeb674 <+214>: flw ft2,0(t5) | 0x0000002ad7aeb678 <+218>: flw fa2,0(t4) | 0x0000002ad7aeb67c <+222>: flw ft0,0(t6) | 0x0000002ad7aeb680 <+226>: fsub.s ft4,fa3,ft1 | 0x0000002ad7aeb684 <+230>: fsub.s ft6,fa3,ft2 | 0x0000002ad7aeb688 <+234>: fsub.s ft7,fa3,fa2 | 0x0000002ad7aeb68c <+238>: fsub.s fa0,fa3,ft0 | 0x0000002ad7aeb690 <+242>: addi t1,t1,4 | 0x0000002ad7aeb692 <+244>: fmadd.s fa4,ft4,ft4,fa4 | 0x0000002ad7aeb696 <+248>: fmadd.s ft3,ft6,ft6,ft3 | 0x0000002ad7aeb69a <+252>: fmadd.s ft5,ft7,ft7,ft5 | 0x0000002ad7aeb69e <+256>: fmadd.s fa5,fa0,fa0,fa5 | 0x0000002ad7aeb6a2 <+260>: beq a5,t1,0x2ad7aeb7cc <_ZN5faiss18fvec_L2sqr_batch_4EPKfS1_S1_S1_S1_mRfS2_S2_S2_+558> | 0x0000002ad7aeb6a6 <+264>: add t0,a0,t1 | 0x0000002ad7aeb6aa <+268>: add t3,a1,t1 | 0x0000002ad7aeb6ae <+272>: flw fa6,0(t0) | 0x0000002ad7aeb6b2 <+276>: flw fa7,0(t3) | 0x0000002ad7aeb6b6 <+280>: add t5,a2,t1 | 0x0000002ad7aeb6ba <+284>: add t6,a4,t1 | 0x0000002ad7aeb6be <+288>: flw ft8,0(t5) | => 0x0000002ad7aeb6c2 <+292>: flw ft9,0(t6) | 0x0000002ad7aeb6c6 <+296>: add t4,a3,t1 | 0x0000002ad7aeb6ca <+300>: fsub.s ft10,fa6,fa7 | 0x0000002ad7aeb6ce <+304>: flw fa1,0(t4) | 0x0000002ad7aeb6d2 <+308>: add t3,a0,t1 | 0x0000002ad7aeb6d6 <+312>: add t5,a1,t1 | 0x0000002ad7aeb6da <+316>: flw fa0,4(t3) | 0x0000002ad7aeb6de <+320>: fsub.s ft11,fa6,ft8 | 0x0000002ad7aeb6e2 <+324>: fsub.s fa3,fa6,ft9 | 0x0000002ad7aeb6e6 <+328>: flw fa2,4(t5) | 0x0000002ad7aeb6ea <+332>: fsub.s ft7,fa6,fa1 | 0x0000002ad7aeb6ee <+336>: add t6,a2,t1 | 0x0000002ad7aeb6f2 <+340>: add t4,a3,t1 | 0x0000002ad7aeb6f6 <+344>: add t0,a4,t1 | 0x0000002ad7aeb6fa <+348>: fmadd.s ft2,ft10,ft10,fa4 | 0x0000002ad7aeb6fe <+352>: flw ft1,4(t6) | 0x0000002ad7aeb702 <+356>: fsub.s fa4,fa0,fa2 | 0x0000002ad7aeb706 <+360>: flw ft0,4(t4) | 0x0000002ad7aeb70a <+364>: flw ft6,4(t0) | 0x0000002ad7aeb70e <+368>: add t5,a0,t1 | 0x0000002ad7aeb712 <+372>: add t6,a1,t1 | 0x0000002ad7aeb716 <+376>: fmadd.s ft4,ft11,ft11,ft3 | 0x0000002ad7aeb71a <+380>: fmadd.s ft10,fa3,fa3,fa5 | 0x0000002ad7aeb71e <+384>: flw ft11,8(t6) | 0x0000002ad7aeb722 <+388>: flw fa5,8(t5) | 0x0000002ad7aeb726 <+392>: fmadd.s ft3,ft7,ft7,ft5 | 0x0000002ad7aeb72a <+396>: fsub.s ft9,fa0,ft6 | 0x0000002ad7aeb72e <+400>: fsub.s fa6,fa0,ft1 | 0x0000002ad7aeb732 <+404>: fsub.s fa7,fa0,ft0 | 0x0000002ad7aeb736 <+408>: add t0,a2,t1 | 0x0000002ad7aeb73a <+412>: add t4,a3,t1 | 0x0000002ad7aeb73e <+416>: add t3,a4,t1 | 0x0000002ad7aeb742 <+420>: fmadd.s ft8,fa4,fa4,ft2 | 0x0000002ad7aeb746 <+424>: fsub.s fa3,fa5,ft11 | 0x0000002ad7aeb74a <+428>: flw fa1,8(t0) | 0x0000002ad7aeb74e <+432>: flw ft7,8(t4) | 0x0000002ad7aeb752 <+436>: flw ft5,8(t3) | 0x0000002ad7aeb756 <+440>: fmadd.s fa4,ft9,ft9,ft10 | 0x0000002ad7aeb75a <+444>: fmadd.s ft1,fa6,fa6,ft4 | 0x0000002ad7aeb75e <+448>: fsub.s ft6,fa5,fa1 | 0x0000002ad7aeb762 <+452>: fmadd.s ft0,fa7,fa7,ft3 | 0x0000002ad7aeb766 <+456>: fsub.s fa2,fa5,ft7 | 0x0000002ad7aeb76a <+460>: fsub.s fa6,fa5,ft5 | 0x0000002ad7aeb76e <+464>: add t0,a0,t1 | 0x0000002ad7aeb772 <+468>: add t6,a1,t1 | 0x0000002ad7aeb776 <+472>: add t5,a2,t1 | 0x0000002ad7aeb77a <+476>: add t4,a3,t1 | 0x0000002ad7aeb77e <+480>: add t3,a4,t1 | 0x0000002ad7aeb782 <+484>: flw fa7,12(t0) | 0x0000002ad7aeb786 <+488>: fmadd.s fa0,fa3,fa3,ft8 | 0x0000002ad7aeb78a <+492>: flw ft3,12(t3) | 0x0000002ad7aeb78e <+496>: flw ft4,12(t6) | 0x0000002ad7aeb792 <+500>: flw ft8,12(t5) | 0x0000002ad7aeb796 <+504>: flw ft2,12(t4) | 0x0000002ad7aeb79a <+508>: fmadd.s fa5,fa6,fa6,fa4 | 0x0000002ad7aeb79e <+512>: fsub.s fa3,fa7,ft3 | 0x0000002ad7aeb7a2 <+516>: fsub.s ft9,fa7,ft4 | 0x0000002ad7aeb7a6 <+520>: fmadd.s ft10,ft6,ft6,ft1 | 0x0000002ad7aeb7aa <+524>: fsub.s ft11,fa7,ft8 | 0x0000002ad7aeb7ae <+528>: fmadd.s fa1,fa2,fa2,ft0 | 0x0000002ad7aeb7b2 <+532>: fsub.s ft7,fa7,ft2 | 0x0000002ad7aeb7b6 <+536>: addi t1,t1,16 | 0x0000002ad7aeb7b8 <+538>: fmadd.s fa4,ft9,ft9,fa0 | 0x0000002ad7aeb7bc <+542>: fmadd.s ft3,ft11,ft11,ft10 | 0x0000002ad7aeb7c0 <+546>: fmadd.s fa5,fa3,fa3,fa5 | 0x0000002ad7aeb7c4 <+550>: fmadd.s ft5,ft7,ft7,fa1 | 0x0000002ad7aeb7c8 <+554>: bne a5,t1,0x2ad7aeb6a6 <_ZN5faiss18fvec_L2sqr_batch_4EPKfS1_S1_S1_S1_mRfS2_S2_S2_+264> | 0x0000002ad7aeb7cc <+558>: fsw fa4,0(a6) | 0x0000002ad7aeb7d0 <+562>: ld a0,8(sp) | 0x0000002ad7aeb7d2 <+564>: fsw ft3,0(a7) | 0x0000002ad7aeb7d6 <+568>: fsw ft5,0(t2) | 0x0000002ad7aeb7da <+572>: fsw fa5,0(a0) | 0x0000002ad7aeb7de <+576>: ret | 0x0000002ad7aeb7e0 <+578>: fmv.w.x fa5,zero | 0x0000002ad7aeb7e4 <+582>: ld a0,8(sp) | 0x0000002ad7aeb7e6 <+584>: fmv.s fa4,fa5 | 0x0000002ad7aeb7ea <+588>: fmv.s ft3,fa5 | 0x0000002ad7aeb7ee <+592>: fmv.s ft5,fa5 | 0x0000002ad7aeb7f2 <+596>: fsw fa4,0(a6) | 0x0000002ad7aeb7f6 <+600>: fsw ft3,0(a7) | 0x0000002ad7aeb7fa <+604>: fsw ft5,0(t2) | 0x0000002ad7aeb7fe <+608>: fsw fa5,0(a0) | 0x0000002ad7aeb802 <+612>: ret At this stage, I haven't debugged it further. I'll try to see if I can reproduce the issue on another architecture. Given it's not a regression, I guess the severity can be decreased. Regards Aurelien [1] https://ci.debian.net/packages/f/faiss/testing/riscv64/74151428/ -- Aurelien Jarno GPG: 4096R/1DDD8C9B [email protected] http://aurel32.net
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