From e17ec20bcd89150581027394111b36ce247ab4c4 Mon Sep 17 00:00:00 2001
From: Erik Johnston <erik@matrix.org>
Date: Tue, 19 May 2026 17:01:10 +0100
Subject: [PATCH] Fixup

---
 Cargo.lock                  |  5 +++--
 rust/Cargo.toml             |  1 +
 rust/src/lib.rs             | 22 ++++++++++++----------
 synapse/metrics/jemalloc.py |  2 +-
 4 files changed, 17 insertions(+), 13 deletions(-)

diff --git a/Cargo.lock b/Cargo.lock
index 1d56fc1ec3..a0a6cd4bde 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -689,9 +689,9 @@ checksum = "bbd2bcb4c963f2ddae06a2efc7e9f3591312473c50c6685e1f298068316e66fe"
 
 [[package]]
 name = "libc"
-version = "0.2.174"
+version = "0.2.186"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "1171693293099992e19cddea4e8b849964e9846f4acee11b3948bcc337be8776"
+checksum = "68ab91017fe16c622486840e4c83c9a37afeff978bd239b5293d61ece587de66"
 
 [[package]]
 name = "libm"
@@ -1330,6 +1330,7 @@ dependencies = [
  "icu_segmenter",
  "itertools",
  "lazy_static",
+ "libc",
  "log",
  "mime",
  "once_cell",
diff --git a/rust/Cargo.toml b/rust/Cargo.toml
index 5d1609e677..608f7a688f 100644
--- a/rust/Cargo.toml
+++ b/rust/Cargo.toml
@@ -69,6 +69,7 @@ tikv-jemallocator = { version = "0.6.1", features = [
 tikv-jemalloc-sys = { version = "0.6.1", features = [
     "disable_initial_exec_tls",
 ] }
+libc = "0.2.186"
 
 [build-dependencies]
 blake2 = "0.10.4"
diff --git a/rust/src/lib.rs b/rust/src/lib.rs
index 1fe4496317..f5c562bcf4 100644
--- a/rust/src/lib.rs
+++ b/rust/src/lib.rs
@@ -20,6 +20,8 @@ pub mod rendezvous;
 pub mod room_versions;
 pub mod segmenter;
 
+use libc::{c_char, c_int, c_void, size_t};
+
 #[global_allocator]
 static GLOBAL: Jemalloc = Jemalloc;
 
@@ -92,32 +94,32 @@ impl<T> UnwrapInfallible<T> for Result<T, Infallible> {
 }
 
 #[no_mangle]
-pub unsafe extern "C" fn malloc(size: usize) -> *mut std::ffi::c_void {
+pub unsafe extern "C" fn malloc(size: size_t) -> *mut c_void {
     tikv_jemalloc_sys::malloc(size)
 }
 
 #[no_mangle]
-pub unsafe extern "C" fn calloc(number: usize, size: usize) -> *mut std::ffi::c_void {
+pub unsafe extern "C" fn calloc(number: size_t, size: size_t) -> *mut c_void {
     tikv_jemalloc_sys::calloc(number, size)
 }
 
 #[no_mangle]
-pub unsafe extern "C" fn realloc(ptr: *mut std::ffi::c_void, size: usize) -> *mut std::ffi::c_void {
+pub unsafe extern "C" fn realloc(ptr: *mut c_void, size: size_t) -> *mut c_void {
     tikv_jemalloc_sys::realloc(ptr, size)
 }
 
 #[no_mangle]
-pub unsafe extern "C" fn free(ptr: *mut std::ffi::c_void) {
+pub unsafe extern "C" fn free(ptr: *mut c_void) {
     tikv_jemalloc_sys::free(ptr)
 }
 
 #[no_mangle]
 pub unsafe extern "C" fn mallctl(
-    name: *const std::ffi::c_char,
-    oldp: *mut std::ffi::c_void,
-    oldlenp: *mut usize,
-    newp: *mut std::ffi::c_void,
-    newlen: usize,
-) -> i32 {
+    name: *const c_char,
+    oldp: *mut c_void,
+    oldlenp: *mut size_t,
+    newp: *mut c_void,
+    newlen: size_t,
+) -> c_int {
     tikv_jemalloc_sys::mallctl(name, oldp, oldlenp, newp, newlen)
 }
diff --git a/synapse/metrics/jemalloc.py b/synapse/metrics/jemalloc.py
index 03cecec3ca..ef0b4905a8 100644
--- a/synapse/metrics/jemalloc.py
+++ b/synapse/metrics/jemalloc.py
@@ -161,7 +161,7 @@ def _setup_jemalloc_stats() -> None:
 
     # We're looking for a path at the end of the line that includes
     # "libjemalloc".
-    regex = re.compile(r"/\S+/libjemalloc.*$")
+    regex = re.compile(r"/\S+/synapse_rust\.abi3\.so$")
 
     jemalloc_path = None
     with open("/proc/self/maps") as f: