SetPermissions fails because errno != ENOMEM

[healytpk]

I have webspace on a remote Linux server, and I want to run NodeJs v21 on it, but the first obstacle was that the remote server only has glibc v2.27, so the prebuilt binary for the latest version won't work.
So I downloaded an earlier version of Ubuntu that ships with glibc v2.27, put it in a virtual machine, and built NodeJs v21.6.1 linked with glibc v2.27.
I copied the 'node' binary across to the remote server, but it failed to run because the remote server's version of libstdc++ was too old.
So next I re-built the binary with -static-libstdc++ , and so now the binary can run on the remote server, but it crashes because errno is compared against ENOMEM somewhere (note that ENOMEM == 12). I think this failure is occurring in the file 'platform-posix.cc' on line 494 where CHECK_EQ is used to ensure that errno is equal to ENOMEM.
Does anyone know what might be going wrong here? Here's what I'm seeing at the command line:

#
# Fatal error in , line 0
# Check failed: 12 == (*__errno_location ()).
#
#
#
#FailureMessage Object: 0x7dfbc0167100
----- Native stack trace -----

 1: 0x1eead6b12a01  [./node]
 2: 0x1eead8113dc1 V8_Fatal(char const*, ...) [./node]
 3: 0x1eead811e0ef v8::base::OS::SetPermissions(void*, unsigned long, v8::base::OS::MemoryPermission) [./node]
 4: 0x1eead6fb8cbc v8::internal::MemoryAllocator::SetPermissionsOnExecutableMemoryChunk(v8::internal::VirtualMemory*, unsigned long, unsigned long, unsigned long) [./node]
 5: 0x1eead6fb8fe5 v8::internal::MemoryAllocator::AllocateAlignedMemory(unsigned long, unsigned long, unsigned long, v8::internal::AllocationSpace, v8::internal::Executability, void*, v8::internal::VirtualMemory*) [./node]
 6: 0x1eead6fb926f v8::internal::MemoryAllocator::AllocateUninitializedChunkAt(v8::internal::BaseSpace*, unsigned long, v8::internal::Executability, unsigned long, v8::internal::PageSize) [./node]
 7: 0x1eead6fb945e v8::internal::MemoryAllocator::AllocatePage(v8::internal::MemoryAllocator::AllocationMode, v8::internal::Space*, v8::internal::Executability) [./node]
 8: 0x1eead6fdbed3 v8::internal::PagedSpaceBase::TryExpandBackground(unsigned long) [./node]
 9: 0x1eead6ee8228 v8::internal::ConcurrentAllocator::AllocateFromSpaceFreeList(unsigned long, unsigned long, v8::internal::AllocationOrigin) [./node]
10: 0x1eead6ee87ff v8::internal::ConcurrentAllocator::AllocateOutsideLab(int, v8::internal::AllocationAlignment, v8::internal::AllocationOrigin) [./node]
11: 0x1eead6f27fce v8::internal::Factory::CodeBuilder::AllocateUninitializedInstructionStream(bool) [./node]
12: 0x1eead6f28065 v8::internal::Factory::CodeBuilder::BuildInternal(bool) [./node]
13: 0x1eead6d6d0d0 v8::internal::baseline::BaselineCompiler::Build(v8::internal::LocalIsolate*) [./node]
14: 0x1eead6d7d84f v8::internal::GenerateBaselineCode(v8::internal::Isolate*, v8::internal::Handle<v8::internal::SharedFunctionInfo>) [./node]
15: 0x1eead6dd632b v8::internal::Compiler::CompileSharedWithBaseline(v8::internal::Isolate*, v8::internal::Handle<v8::internal::SharedFunctionInfo>, v8::internal::Compiler::ClearExceptionFlag, v8::internal::IsCompiledScope*) [./node]
16: 0x1eead6dd6853 v8::internal::Compiler::CompileBaseline(v8::internal::Isolate*, v8::internal::Handle<v8::internal::JSFunction>, v8::internal::Compiler::ClearExceptionFlag, v8::internal::IsCompiledScope*) [./node]
17: 0x1eead6d6ab8f v8::internal::baseline::BaselineBatchCompiler::CompileBatch(v8::internal::Handle<v8::internal::JSFunction>) [./node]
18: 0x1eead6de4f32 v8::internal::Compiler::Compile(v8::internal::Isolate*, v8::internal::Handle<v8::internal::JSFunction>, v8::internal::Compiler::ClearExceptionFlag, v8::internal::IsCompiledScope*) [./node]
19: 0x1eead738c92c v8::internal::Runtime_CompileLazy(int, unsigned long*, v8::internal::Isolate*) [./node]
20: 0x6fede7ea53f6 
Trace/breakpoint trap

[healytpk]

Just now I've edited the code so that prints out the return value of 'mprotect', and also if the return value is non-zero, then it sets it to ENOMEM in an attempt to keep things going. It's rebuilding now and I'll be able to try it shortly.

[healytpk]

Why does NodeJs need to use mprotect on Linux? Does it generate CPU instructions at runtime, and then execute them? Is that why it needs to set a page as exectuable?

[healytpk]

I've been doing some testing on my remote webserver, and I first tried:
(1) Use mprotect to set a malloc'd page to executable
This failed. So next I tried:
(2) Use mprotect to set a readonly executable page as writeable
This also failed. So it looks like I won't be able to do "just in time compilation" or "self-modifying code" on my remote server.
But I have a third idea that I need to implement:
(3) Write the CPU instructions to an object file, then use ld at the command line to create a shared library (i.e. .so file). Use 'dlopen' to load the shared library into node and then execute the code.

Does anyone wanna help me implement the 3rd option? I have experience doing this kind of thing.

[healytpk]

I've posted to the v8 forum about this:
https://groups.google.com/g/v8-dev/c/-jTDeGYd3oc

[healytpk]

I have a proof of concept working here in which I achieve JIT by editing an .SO file:
https://github.com/healytpk/just_in_time/

[healytpk]

Turns out I can do:

node --jitless

and the argument will be passed to v8 to ensure that it doesn't do any Just In Time.