miri is incorrectly built with jemalloc on some targets

[pitust]

I tried to run cargo miri run in (any) workspace on Asahi Linux (which has 16k page kernels)

I expected to see this happen: The program runs under miri similarly to how rustc works

Instead, this happened:

thread 'main' panicked at src/tools/miri/cargo-miri/src/phases.rs:103:9:
failed to determine underlying rustc version of Miri (MIRI_BE_RUSTC="host" "/home/pitust/.rustup/toolchains/nightly-aarch64-unknown-linux-gnu/bin/miri"):
CommandError { stdout: "", stderr: "<jemalloc>: Unsupported system page size\n<jemalloc>: Unsupported system page size\nterminate called without an active exception\n" }
stack backtrace:
   0: rust_begin_unwind
             at /rustc/5e1440ae514d98ddfcbf1607acb64d41e07ef616/library/std/src/panicking.rs:681:5
   1: core::panicking::panic_fmt
             at /rustc/5e1440ae514d98ddfcbf1607acb64d41e07ef616/library/core/src/panicking.rs:75:14
   2: cargo_miri::phases::phase_cargo_miri::<std::env::Args>
   3: cargo_miri::main
note: Some details are omitted, run with `RUST_BACKTRACE=full` for a verbose backtrace.

Meta

rustc --version --verbose:

rustc 1.85.0-nightly (5e1440ae5 2024-12-01)
binary: rustc
commit-hash: 5e1440ae514d98ddfcbf1607acb64d41e07ef616
commit-date: 2024-12-01
host: aarch64-unknown-linux-gnu
release: 1.85.0-nightly
LLVM version: 19.1.4

[Noratrieb]

Foe context: jemalloc does not work on Linux with 16k pages, it hardcodes 4k: jemalloc/jemalloc#467
rustc works, so I suspect it's not being built with jemalloc on that target. Miris jenalloc logic is unconditional and not coupled to bootstrap jenalloc logic, which seems like the problem.

[Mark-Simulacrum]

That issue makes it sound like jemalloc should be able to work on this system (i.e., the hardcoding was removed?) if we (or maybe jemalloc-sys?) compiled it with e.g. a 64k "page" target? At least, that's my impression of the closing comment.

[Noratrieb]

Yes, we could compile jemalloc to make it work properly (and actually maybe that's what's already happening for rustc? unsure)

[marcan]

Yes, 64K page mode is universal. For some vague performance-related reasons, jemalloc refuse to default to that on ARM64 and instead use 4K mode, which does not work with any other page size. You have to set --with-lg-page=16 to compile in 64K page mode, and then that will work on all targets.

[mrkajetanp]

This should be reopened after all, it needs its own fix. I think the miri you get from rustup component add miri needs to be built with the 64k page-supporting toolchain and currently it's not.