[Pkg-rust-maintainers] Bug#1136400: rist-libmimalloc-sys: autopktest regression on riscv64

[Aurelien Jarno]

control: retitle -1 mimalloc: riscv64: build-time MMU detection causes crashes on SV48 systems
control: reassign -1 src:mimalloc
control: found -1 3.0.1+ds-1

Hi,

On 2026-05-14 22:09, Aurelien Jarno wrote:
> On 2026-05-14 13:02, Aurelien Jarno wrote:
> > Hi,
> > 
> > On 2026-05-14 01:02, Peter Green wrote:
> > > found 1136400 0.1.40-1
> > > thanks
> > > 
> > > I believe you've quoted the wrong part of the log,
> > > quoting output from a test that is already marked as "broken".
> > > 
> > > I belive the actual failure is.
> > > 
> > > 142s   process didn't exit successfully: `CARGO=/usr/bin/cargo CARGO_MANIFEST_DIR=/usr/share/cargo/registry/libmimalloc-sys-0.1.40 CARGO_MANIFEST_PATH=/usr/share/cargo/registry/libmimalloc-sys-0.1.40/Cargo.toml CARGO_PKG_AUTHORS='Octavian Oncescu <octavonce at gmail.com>' CARGO_PKG_DESCRIPTION='Sys crate wrapping the mimalloc allocator' CARGO_PKG_HOMEPAGE='' CARGO_PKG_LICENSE=MIT CARGO_PKG_LICENSE_FILE='' CARGO_PKG_NAME=libmimalloc-sys CARGO_PKG_README='' CARGO_PKG_REPOSITORY='https://github.com/purpleprotocol/mimalloc_rust/tree/master/libmimalloc-sys' CARGO_PKG_RUST_VERSION='' CARGO_PKG_VERSION=0.1.40 CARGO_PKG_VERSION_MAJOR=0 CARGO_PKG_VERSION_MINOR=1 CARGO_PKG_VERSION_PATCH=40 CARGO_PKG_VERSION_PRE='' LD_LIBRARY_PATH='/tmp/tmp.YhgzhQ6wzU/target/riscv64gc-unknown-linux-gnu/debug:/tmp/tmp.YhgzhQ6wzU/target/riscv64gc-unknown-linux-gnu/debug/deps:/usr/lib/rustlib/riscv64gc-unknown-linux-gnu/lib' OUT_DIR=/tmp/tmp.YhgzhQ6wzU/target/riscv64gc-unknown-linux-gnu/debug/build/libmimalloc-sys-4d9f02f6027bf000/out /tmp/tmp.YhgzhQ6wzU/target/riscv64gc-unknown-linux-gnu/debug/deps/libmimalloc_sys-ceadfc72acec09f8` (signal: 11, SIGSEGV: invalid memory reference)
> > > 142s autopkgtest [05:06:41]: test librust-libmimalloc-sys-dev:arena: -----------------------]
> > 
> > I am personally unable to reproduce the issue on two different boards, 
> > using JH7110 and SpacemiT K1 CPU. That said after retrying the 
> > autopkgtest a few time on debci (it runs fast), I have noticed the 
> > following pattern:
> > - Tests pass on debci-10 running Linux 6.12.86+deb13-riscv64
> > - Tests fail on debci-31, debci-32 and debci-33 running Linux 6.6.88-win2030
> > 
> > Therefore I believe it could be a kernel or a hardware issue. I guess 
> > the boards running the 6.6.88-win2030 kernel are the P550 ones.
> 
> I am able to reproduce the issue on a P550 board, either running kernel 
> 6.6.77, 6.12.33 or 6.12.78. I am also able to reproduce it on the same 
> hardware in a VM running kernel 6.12.86+deb13-riscv64.
> 
> On the other hand I am unable to reproduce it on the riscv64 porterbox 
> (ricci.d.o).
> 
> I therefore believe there is something fishy with the hardware that 
> needs more investigation.

I finally found the issue. It is in mimalloc, which contains the 
following build time check:

| # Check /proc/cpuinfo for an SV39 MMU and limit the virtual address bits.
| # (this will skip the aligned hinting in that case. Issue #939, #949)
| if (EXISTS /proc/cpuinfo)
|   file(STRINGS /proc/cpuinfo mi_sv39_mmu REGEX "^mmu[ \t]+:[ \t]+sv39$")
|   if (mi_sv39_mmu)
|     MESSAGE( STATUS "Set virtual address bits to 39 (SV39 MMU detected)" )
|     list(APPEND mi_defines MI_DEFAULT_VIRTUAL_ADDRESS_BITS=39)
|   endif()
| endif()

Our build daemons are using a sv39 nmu:

| aurel32 at ricci:~$ grep ^mmu /proc/cpuinfo  | head -n1
| mmu             : sv39

While the P550 defaults to a sv48 nmu:
| aurel32 at p550:~$ grep ^mmu /proc/cpuinfo  | head -n1
| mmu             : sv48

Therefore libmimalloc.so.3 is built with a 39-bit virtual address space
support. When the binary is run on a sv48 system, things explodes.  
Rebuilding libmimalloc.so.3 on the P550 enables sv48 support and things 
work again, even on a sv39 mmu.

It's not clear to me if there is a drawback to always enable sv48 
support, if yes I guess a runtime detection should be implemented. 
Anyway for now reassigning the bug to the correct package.

Regards
Aurelien

-- 
Aurelien Jarno                          GPG: 4096R/1DDD8C9B
aurelien at aurel32.net                     http://aurel32.net