Preload doesn't prevent crashing on module load for older versions

[zackcam]

We were looking at using preload in Bloom, by moving the following code from init to preload.

    let ver = ctx
        .get_server_version()
        .expect("Unable to get server version!");
    if !valid_server_version(ver) {
        ctx.log_warning(
            format!(
                "The minimum supported Valkey server version for the valkey-bloom module is {:?}",
                configs::BLOOM_MIN_SUPPORTED_VERSION
            )
            .as_str(),
        );
        Status::Err
    } else {
        Status::Ok
    }

From my understanding this should run before trying to load the module and reject it without crashing if the server is not on a supported version.

When testing this for a valkey server with version 7.2 I would see this in the logs followed by a crash

=== REDIS BUG REPORT START: Cut & paste starting from here ===
33463:M 29 Apr 2025 21:02:09.227 # valkey 7.2.5 crashed by signal: 11, si_code: 1
33463:M 29 Apr 2025 21:02:09.227 # Accessing address: (nil)

From then getting the stack trace we see:

(gdb) c
Continuing.

Thread 1 "valkey-server" received signal SIGSEGV, Segmentation fault.
0x0000000000000000 in ?? ()
Missing separate debuginfos, use: debuginfo-install libgcc-7.3.1-17.amzn2.x86_64
(gdb) bt
#0  0x0000000000000000 in ?? ()
#1  0x00007f1fdff21b44 in RedisModule_Init (ctx=0x7ffd6bf4a9c0, 
    name=0x7ffd6bf493f8 "bf", ver=999999, apiver=1)
    at src/include/redismodule.h:1683
#2  0x00007f1fdff21b77 in Export_RedisModule_Init (
    ctx=0x7ffd6bf4a9c0, name=0x7ffd6bf493f8 "bf", ver=999999, 
    apiver=1) at src/redismodule.c:8
#3  0x00007f1fdfec1f9d in valkey_bloom::RedisModule_OnLoad (
    ctx=0x7ffd6bf4a9c0, argv=0x0, argc=0)
    at /workplace/zackcam/valkeymodule-rs/src/macros.rs:286
#4  0x00000000004e53b6 in moduleLoad (
    path=0x7f1fea42a193 "/home/zackcam/workplace/valkey-bloom/target/release/libvalkey_bloom.so", module_argv=0x0, module_argc=0, 
    is_loadex=is_loadex@entry=0) at module.c:12176
#5  0x00000000004e566e in moduleCommand (c=0x7f1fea528700)
    at module.c:13022
#6  0x00000000004fba82 in call (c=c@entry=0x7f1fea528700, 
    flags=flags@entry=3) at server.c:3519
#7  0x00000000004fc804 in processCommand (c=0x7f1fea528700)
    at server.c:4160
#8  0x0000000000496b57 in processCommandAndResetClient (
    c=0x7f1fea528700) at networking.c:2466
#9  processInputBuffer (c=c@entry=0x7f1fea528700)
    at networking.c:2574
#10 0x000000000049708b in readQueryFromClient (
    conn=<optimized out>) at networking.c:2713
#11 0x000000000054b6a4 in callHandler (handler=<optimized out>, 
    conn=0x7f1fea429580) at connhelpers.h:79
#12 connSocketEventHandler.lto_priv.355 (el=<optimized out>, 
    fd=<optimized out>, clientData=0x7f1fea429580, 
    mask=<optimized out>) at socket.c:298
#13 0x0000000000458c7e in aeProcessEvents (
    eventLoop=eventLoop@entry=0x7f1fea42a140, 
---Type <return> to continue, or q <return> to quit---
    flags=flags@entry=27) at ae.c:436
#14 0x0000000000458fd8 in aeMain (eventLoop=0x7f1fea42a140)
    at ae.c:496
#15 0x000000000044fd81 in main (argc=<optimized out>, 
    argv=<optimized out>) at server.c:7373

This appears to crash on RedisModule_Init before we reach the preload, is this use case invalid for preload or is there an edge case where preload doesn't catch this?
I compared the stack traces for when using init and preload and they were the same as well

[dmitrypol]

I was not able to repro this with either valkey-server 7.2.5 or 7.2.8 on Mac Sequoia 15.4.1 with latest code and either debug or release builds. Can you tell me more about your environment and provide more detailed steps? Here are my steps:

git pull
change lib.rs
valkey_module! {
    preload: initialize,
}
cargo build
cargo build --release
valkey-server --enable-module-command yes
valkey-cli
module load /path/here/libvalkey_bloom.dylib

in server logs:
# <bf> The minimum supported Valkey server version for the valkey-bloom module is [8, 0, 0]
# Module .../libvalkey_bloom.dylib initialization failed. Module not loaded

[zackcam]

I made the changes: https://github.com/valkey-io/valkey-bloom/pull/64/files.
After doing these changes I ran ./build.sh and then found the binary. (I also tried compiling with using cargo build and cargo build --release as you did above and still had the same result below)
After this I ran make valkey-server and make valkey-cli on 7.2.5 version of Valkey.
I then followed as above with:
valkey-server --enable-module-command yes
Where I do see as the server is starting up:

17618:C 05 May 2025 19:30:21.111 * Valkey version=7.2.5, bits=64, commit=26388270, modified=0, pid=17618, just started

Then:

valkey-cli
module load /path/here/libvalkey_bloom.so 

I still get the same error messages as above when going through the steps outlined
More details on my environement:

./src/valkey-server --version
Server v=7.2.5 sha=26388270:0 malloc=jemalloc-5.3.0 bits=64 build=1f77e284c39a2e20


rustc --version
cargo --version

rustc 1.86.0 (05f9846f8 2025-03-31)
cargo 1.86.0 (adf9b6ad1 2025-02-28)

Let me know what other information could be helpful!