Issue #19234 has been reported by byroot (Jean Boussier). ---------------------------------------- Bug #19234: [3.2.0dev] YJIT code GC can lead to crashes https://bugs.ruby-lang.org/issues/19234 * Author: byroot (Jean Boussier) * Status: Open * Priority: Normal * Assignee: k0kubun (Takashi Kokubun) * Target version: 3.2 * ruby -v: ruby 3.2.0dev (2022-12-13T16:07:29Z master a66a69865d) +YJIT [x86_64-linux] * Backport: 2.7: UNKNOWN, 3.0: UNKNOWN, 3.1: UNKNOWN ---------------------------------------- Filing this bug here in case some people may have observed it too and may have more information, and also to keep track of it for the upcoming 3.2.0 release. After changing some settings on our CI to make sure YJIT's `code_gc` would trigger, we discovered that it sometimes cause crashes. The crash can take many different form (e.g. `[BUG] Segmentation fault at 0x00005604a8e78006` or `[BUG] Illegal instruction at 0x0000aaaacc0ce4c0`), and happens on both `x86` and `arm64`. It however happens very consistently on our CI, but only after running for 15 to 20 minutes and we haven't been able to reduce it to a local reproduction script. When it happens however the backtrace isn't really helpful: ``` -- C level backtrace information ------------------------------------------- /usr/local/ruby/bin/real-ruby(rb_print_backtrace+0x11) [0x5604a8a6df7d] vm_dump.c:770 /usr/local/ruby/bin/real-ruby(rb_vm_bugreport) vm_dump.c:1065 /usr/local/ruby/bin/real-ruby(rb_bug_for_fatal_signal+0xee) [0x5604a8ba927e] error.c:813 /usr/local/ruby/bin/real-ruby(sigsegv+0x4d) [0x5604a89c3ded] signal.c:964 /lib/x86_64-linux-gnu/libpthread.so.0(__restore_rt+0x0) [0x7fb5b4285420] [0x5604acd31079] ```` Like regular GC bugs, it is likely that the code GC need to trigger at a very specific place for the bug to happen. Our attempts at triggering it manually with `RubyVM::YJIT.code_gc` or to set the executable memory very low to trigger it more often didn't allow for a simpler reproduction. Both @k0kubun and @alanwu are investigating it right now. -- https://bugs.ruby-lang.org/