I would:

• Check with glib that this is definitely not a glib bug (doesn't look like it)
• Report to LLVM
• hardeningDisable = [ "stackprotecter" ]; in glib with a link to the LLVM bug report

hmm… prolly makes sense to default to the 64K-compatible setting for jemalloc then, just to cover more systems. as said, the 64K setting should work on 4K systems? it might just not be optimal (at least according to an upstream issue on raising the aarch64 default from 4K to 64K).

a function argument to override that would prolly still be nice though - could be interesting for someone measuring the performance impact and deciding to optimise for their system via an overlay.

diff --git a/pkgs/by-name/je/jemalloc/package.nix b/pkgs/by-name/je/jemalloc/package.nix
index 202195c152db..88e7b776b28d 100644
--- a/pkgs/by-name/je/jemalloc/package.nix
+++ b/pkgs/by-name/je/jemalloc/package.nix
@@ -13,6 +13,18 @@
   # compatibility.
   stripPrefix ? stdenv.hostPlatform.isDarwin,
   disableInitExecTls ? false,
+  # The upstream default is dependent on the builders' page size
+  # https://github.com/jemalloc/jemalloc/issues/467
+  # https://sources.debian.org/src/jemalloc/5.3.0-3/debian/rules/
+  pageSizeLog2 ?
+    if
+      (
+        stdenv.hostPlatform.isAarch64 || stdenv.hostPlatform.isLoongArch64 || stdenv.hostPlatform.isPower64
+      )
+    then
+      16
+    else
+      12,
 }:
 
 stdenv.mkDerivation (finalAttrs: {
@@ -46,21 +58,11 @@ stdenv.mkDerivation (finalAttrs: {
   configureFlags = [
     "--with-version=${lib.versions.majorMinor finalAttrs.version}.0-0-g${finalAttrs.src.rev}"
     "--with-lg-vaddr=${with stdenv.hostPlatform; toString (if isILP32 then 32 else parsed.cpu.bits)}"
+    (lib.strings.withFeatureAs true "lg-page" (toString pageSizeLog2))
   ]
   # see the comment on stripPrefix
   ++ lib.optional stripPrefix "--with-jemalloc-prefix="
   ++ lib.optional disableInitExecTls "--disable-initial-exec-tls"
-  # The upstream default is dependent on the builders' page size
-  # https://github.com/jemalloc/jemalloc/issues/467
-  # https://sources.debian.org/src/jemalloc/5.3.0-3/debian/rules/
-  ++ [
-    (
-      if (stdenv.hostPlatform.isAarch64 || stdenv.hostPlatform.isLoongArch64) then
-        "--with-lg-page=16"
-      else
-        "--with-lg-page=12"
-    )
-  ]
   # See https://github.com/jemalloc/jemalloc/issues/1997
   # Using a value of 48 should work on both emulated and native x86_64-darwin.
   ++ lib.optional (stdenv.hostPlatform.isDarwin && stdenv.hostPlatform.isx86_64) "--with-lg-vaddr=48";

ig