Stop relying on linking details of std’s default allocator

We’ve been bitten before by symbol names changing:
https://github.com/servo/heapsize/pull/46
and upstream is planning to stop using jemalloc by default:
https://github.com/rust-lang/rust/issues/33082#issuecomment-309781465

So use the (relatively) new `#[global_allocator]` attribute
to explicitly select the system allocator on Windows
and jemalloc (now in an external crate) on other platforms.
This choice matches current defaults.

20 files changed, 158 insertions, 62 deletions

diff --git a/Cargo.lock b/Cargo.lock
index 11223a6fdf4..7160c410175 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -348,6 +348,11 @@ dependencies = [
 ]
 
 [[package]]
+name = "cc"
+version = "1.0.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+
+[[package]]
 name = "cexpr"
 version = "0.2.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
@@ -1110,6 +1115,7 @@ dependencies = [
  "range 0.0.1",
  "serde 1.0.14 (registry+https://github.com/rust-lang/crates.io-index)",
  "servo-fontconfig 0.2.1 (registry+https://github.com/rust-lang/crates.io-index)",
+ "servo_allocator 0.0.1",
  "servo_arc 0.0.1",
  "servo_atoms 0.0.1",
  "servo_geometry 0.0.1",
@@ -1440,6 +1446,24 @@ version = "0.3.1"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 
 [[package]]
+name = "jemalloc-sys"
+version = "0.1.3"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+dependencies = [
+ "cc 1.0.1 (registry+https://github.com/rust-lang/crates.io-index)",
+ "libc 0.2.23 (registry+https://github.com/rust-lang/crates.io-index)",
+]
+
+[[package]]
+name = "jemallocator"
+version = "0.1.3"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+dependencies = [
+ "jemalloc-sys 0.1.3 (registry+https://github.com/rust-lang/crates.io-index)",
+ "libc 0.2.23 (registry+https://github.com/rust-lang/crates.io-index)",
+]
+
+[[package]]
 name = "jpeg-decoder"
 version = "0.1.13"
 source = "registry+https://github.com/rust-lang/crates.io-index"
@@ -1571,6 +1595,7 @@ dependencies = [
  "script_traits 0.0.1",
  "selectors 0.19.0",
  "serde_json 1.0.2 (registry+https://github.com/rust-lang/crates.io-index)",
+ "servo_allocator 0.0.1",
  "servo_arc 0.0.1",
  "servo_atoms 0.0.1",
  "servo_config 0.0.1",
@@ -1733,7 +1758,6 @@ dependencies = [
  "euclid 0.15.3 (registry+https://github.com/rust-lang/crates.io-index)",
  "hashglobe 0.1.0",
  "js 0.1.6 (git+https://github.com/servo/rust-mozjs)",
- "kernel32-sys 0.2.2 (registry+https://github.com/rust-lang/crates.io-index)",
  "servo_arc 0.0.1",
  "smallbitvec 1.0.6 (registry+https://github.com/rust-lang/crates.io-index)",
  "smallvec 0.4.3 (registry+https://github.com/rust-lang/crates.io-index)",
@@ -2363,6 +2387,7 @@ dependencies = [
  "heartbeats-simple 0.4.0 (registry+https://github.com/rust-lang/crates.io-index)",
  "influent 0.4.0 (registry+https://github.com/rust-lang/crates.io-index)",
  "ipc-channel 0.9.0 (registry+https://github.com/rust-lang/crates.io-index)",
+ "jemalloc-sys 0.1.3 (registry+https://github.com/rust-lang/crates.io-index)",
  "libc 0.2.23 (registry+https://github.com/rust-lang/crates.io-index)",
  "log 0.3.8 (registry+https://github.com/rust-lang/crates.io-index)",
  "profile_traits 0.0.1",
@@ -2381,6 +2406,7 @@ dependencies = [
  "ipc-channel 0.9.0 (registry+https://github.com/rust-lang/crates.io-index)",
  "profile 0.0.1",
  "profile_traits 0.0.1",
+ "servo_allocator 0.0.1",
 ]
 
 [[package]]
@@ -2630,6 +2656,7 @@ dependencies = [
  "selectors 0.19.0",
  "serde 1.0.14 (registry+https://github.com/rust-lang/crates.io-index)",
  "serde_json 1.0.2 (registry+https://github.com/rust-lang/crates.io-index)",
+ "servo_allocator 0.0.1",
  "servo_arc 0.0.1",
  "servo_atoms 0.0.1",
  "servo_config 0.0.1",
@@ -2922,6 +2949,14 @@ dependencies = [
 ]
 
 [[package]]
+name = "servo_allocator"
+version = "0.0.1"
+dependencies = [
+ "jemallocator 0.1.3 (registry+https://github.com/rust-lang/crates.io-index)",
+ "kernel32-sys 0.2.2 (registry+https://github.com/rust-lang/crates.io-index)",
+]
+
+[[package]]
 name = "servo_arc"
 version = "0.0.1"
 dependencies = [
@@ -3782,6 +3817,7 @@ dependencies = [
 "checksum byteorder 1.0.0 (registry+https://github.com/rust-lang/crates.io-index)" = "c40977b0ee6b9885c9013cd41d9feffdd22deb3bb4dc3a71d901cc7a77de18c8"
 "checksum bytes 0.3.0 (registry+https://github.com/rust-lang/crates.io-index)" = "c129aff112dcc562970abb69e2508b40850dd24c274761bb50fb8a0067ba6c27"
 "checksum caseless 0.1.3 (registry+https://github.com/rust-lang/crates.io-index)" = "8950b075cff75cdabadee97148a8b5816c7cf62e5948a6005b5255d564b42fe7"
+"checksum cc 1.0.1 (registry+https://github.com/rust-lang/crates.io-index)" = "2c674f0870e3dbd4105184ea035acb1c32c8ae69939c9e228d2b11bbfe29efad"
 "checksum cexpr 0.2.0 (registry+https://github.com/rust-lang/crates.io-index)" = "393a5f0088efbe41f9d1fcd062f24e83c278608420e62109feb2c8abee07de7d"
 "checksum cfg-if 0.1.2 (registry+https://github.com/rust-lang/crates.io-index)" = "d4c819a1287eb618df47cc647173c5c4c66ba19d888a6e50d605672aed3140de"
 "checksum cgl 0.2.1 (registry+https://github.com/rust-lang/crates.io-index)" = "86765cb42c2a2c497e142af72517c1b4d7ae5bb2f25dfa77a5c69642f2342d89"
@@ -3873,6 +3909,8 @@ dependencies = [
 "checksum ipc-channel 0.9.0 (registry+https://github.com/rust-lang/crates.io-index)" = "c10ed089b1921b01ef342c736a37ee0788eeb9a5f373bb2df1ba88d01125064f"
 "checksum itertools 0.5.10 (registry+https://github.com/rust-lang/crates.io-index)" = "4833d6978da405305126af4ac88569b5d71ff758581ce5a987dbfa3755f694fc"
 "checksum itoa 0.3.1 (registry+https://github.com/rust-lang/crates.io-index)" = "eb2f404fbc66fd9aac13e998248505e7ecb2ad8e44ab6388684c5fb11c6c251c"
+"checksum jemalloc-sys 0.1.3 (registry+https://github.com/rust-lang/crates.io-index)" = "94fb624d7e8345e5c42caab8d1db6ec925fdadff3fd0cb7dd781b41be8442828"
+"checksum jemallocator 0.1.3 (registry+https://github.com/rust-lang/crates.io-index)" = "1850725977c344d63af66e8fd00857646e3ec936c490cd63667860b7b03ab5c1"
 "checksum jpeg-decoder 0.1.13 (registry+https://github.com/rust-lang/crates.io-index)" = "2805ccb10ffe4d10e06ef68a158ff94c255211ecbae848fbde2146b098f93ce7"
 "checksum js 0.1.6 (git+https://github.com/servo/rust-mozjs)" = "<none>"
 "checksum kernel32-sys 0.2.2 (registry+https://github.com/rust-lang/crates.io-index)" = "7507624b29483431c0ba2d82aece8ca6cdba9382bff4ddd0f7490560c056098d"
diff --git a/components/allocator/Cargo.toml b/components/allocator/Cargo.toml
new file mode 100644
index 00000000000..fccec48a5e9
--- /dev/null
+++ b/components/allocator/Cargo.toml
@@ -0,0 +1,18 @@
+[package]
+name = "servo_allocator"
+version = "0.0.1"
+authors = ["The Servo Project Developers"]
+license = "MPL-2.0"
+publish = false
+
+[lib]
+path = "lib.rs"
+
+[features]
+unstable = ["kernel32-sys", "jemallocator"]
+
+[target.'cfg(not(windows))'.dependencies]
+jemallocator = { version = "0.1.3", optional = true }
+
+[target.'cfg(windows)'.dependencies]
+kernel32-sys = { version = "0.2.1", optional = true }
diff --git a/components/allocator/lib.rs b/components/allocator/lib.rs
new file mode 100644
index 00000000000..e832e485575
--- /dev/null
+++ b/components/allocator/lib.rs
@@ -0,0 +1,62 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+//! Selecting the default global allocator for Servo
+
+#![cfg_attr(all(feature = "unstable", windows), feature(alloc_system, allocator_api))]
+#![cfg_attr(feature = "unstable", feature(global_allocator))]
+
+#[cfg(feature = "unstable")]
+#[global_allocator]
+static ALLOC: platform::Allocator = platform::Allocator;
+
+pub use platform::usable_size;
+
+
+#[cfg(all(feature = "unstable", not(windows)))]
+mod platform {
+    extern crate jemallocator;
+
+    pub use self::jemallocator::Jemalloc as Allocator;
+    use std::os::raw::c_void;
+
+    /// Get the size of a heap block.
+    pub unsafe extern "C" fn usable_size(ptr: *const c_void) -> usize {
+        jemallocator::usable_size(ptr)
+    }
+}
+
+#[cfg(all(feature = "unstable", windows))]
+mod platform {
+    extern crate alloc_system;
+    extern crate kernel32;
+
+    pub use self::alloc_system::System as Allocator;
+    use self::kernel32::{GetProcessHeap, HeapSize, HeapValidate};
+    use std::os::raw::c_void;
+
+    /// Get the size of a heap block.
+    pub unsafe extern "C" fn usable_size(mut ptr: *const c_void) -> usize {
+        let heap = GetProcessHeap();
+
+        if HeapValidate(heap, 0, ptr) == 0 {
+            ptr = *(ptr as *const *const c_void).offset(-1);
+        }
+
+        HeapSize(heap, 0, ptr) as usize
+    }
+}
+
+#[cfg(not(feature = "unstable"))]
+mod platform {
+    use std::os::raw::c_void;
+
+    /// Without `#[global_allocator]` we cannot be certain of what allocator is used
+    /// or how it is linked. We therefore disable memory reporting. (Return zero.)
+    pub unsafe extern "C" fn usable_size(_ptr: *const c_void) -> usize {
+        0
+    }
+}
+
+
diff --git a/components/gfx/Cargo.toml b/components/gfx/Cargo.toml
index 606d17c2908..d28c7b8f44a 100644
--- a/components/gfx/Cargo.toml
+++ b/components/gfx/Cargo.toml
@@ -53,6 +53,7 @@ core-text = "7.0"
 
 [target.'cfg(any(target_os = "linux", target_os = "android"))'.dependencies]
 freetype = "0.3"
+servo_allocator = {path = "../allocator"}
 
 [target.'cfg(target_os = "linux")'.dependencies]
 servo-fontconfig = "0.2.1"
diff --git a/components/gfx/lib.rs b/components/gfx/lib.rs
index aa0c635bf53..418e8d7f897 100644
--- a/components/gfx/lib.rs
+++ b/components/gfx/lib.rs
@@ -27,8 +27,8 @@ extern crate fnv;
 #[cfg(target_os = "linux")]
 extern crate fontconfig;
 extern crate fontsan;
-#[cfg(any(target_os = "linux", target_os = "android"))]
-extern crate freetype;
+#[cfg(any(target_os = "linux", target_os = "android"))] extern crate freetype;
+#[cfg(any(target_os = "linux", target_os = "android"))] extern crate servo_allocator;
 extern crate gfx_traits;
 
 // Eventually we would like the shaper to be pluggable, as many operating systems have their own
diff --git a/components/gfx/platform/freetype/font_context.rs b/components/gfx/platform/freetype/font_context.rs
index c7deea5adf8..8456e2cade2 100644
--- a/components/gfx/platform/freetype/font_context.rs
+++ b/components/gfx/platform/freetype/font_context.rs
@@ -8,7 +8,8 @@ use freetype::freetype::FT_Library;
 use freetype::freetype::FT_Memory;
 use freetype::freetype::FT_MemoryRec_;
 use freetype::freetype::FT_New_Library;
-use malloc_size_of::{malloc_size_of, MallocSizeOf, MallocSizeOfOps};
+use malloc_size_of::{MallocSizeOf, MallocSizeOfOps};
+use servo_allocator::usable_size;
 use std::mem;
 use std::os::raw::{c_long, c_void};
 use std::ptr;
@@ -31,7 +32,7 @@ extern fn ft_alloc(mem: FT_Memory, req_size: c_long) -> *mut c_void {
     mem::forget(vec);
 
     unsafe {
-        let actual_size = malloc_size_of(ptr as *const _);
+        let actual_size = usable_size(ptr as *const _);
         let user = (*mem).user as *mut User;
         (*user).size += actual_size;
     }
@@ -41,7 +42,7 @@ extern fn ft_alloc(mem: FT_Memory, req_size: c_long) -> *mut c_void {
 
 extern fn ft_free(mem: FT_Memory, ptr: *mut c_void) {
     unsafe {
-        let actual_size = malloc_size_of(ptr as *const _);
+        let actual_size = usable_size(ptr as *const _);
         let user = (*mem).user as *mut User;
         (*user).size -= actual_size;
 
@@ -50,13 +51,14 @@ extern fn ft_free(mem: FT_Memory, ptr: *mut c_void) {
     }
 }
 
-extern fn ft_realloc(mem: FT_Memory, _cur_size: c_long, new_req_size: c_long,
+extern fn ft_realloc(mem: FT_Memory, old_size: c_long, new_req_size: c_long,
                      old_ptr: *mut c_void) -> *mut c_void {
     let old_actual_size;
     let mut vec;
     unsafe {
-        old_actual_size = malloc_size_of(old_ptr as *const _);
-        vec = Vec::<u8>::from_raw_parts(old_ptr as *mut u8, old_actual_size, old_actual_size);
+        old_actual_size = usable_size(old_ptr as *const _);
+        let old_size = old_size as usize;
+        vec = Vec::<u8>::from_raw_parts(old_ptr as *mut u8, old_size, old_size);
     };
 
     let new_req_size = new_req_size as usize;
@@ -71,7 +73,7 @@ extern fn ft_realloc(mem: FT_Memory, _cur_size: c_long, new_req_size: c_long,
     mem::forget(vec);
 
     unsafe {
-        let new_actual_size = malloc_size_of(new_ptr as *const _);
+        let new_actual_size = usable_size(new_ptr as *const _);
         let user = (*mem).user as *mut User;
         (*user).size += new_actual_size;
         (*user).size -= old_actual_size;
diff --git a/components/layout_thread/Cargo.toml b/components/layout_thread/Cargo.toml
index 35336e133ca..8683ad60942 100644
--- a/components/layout_thread/Cargo.toml
+++ b/components/layout_thread/Cargo.toml
@@ -40,6 +40,7 @@ script_layout_interface = {path = "../script_layout_interface"}
 script_traits = {path = "../script_traits"}
 selectors = { path = "../selectors" }
 serde_json = "1.0"
+servo_allocator = {path = "../allocator"}
 servo_arc = {path = "../servo_arc"}
 servo_atoms = {path = "../atoms"}
 servo_config = {path = "../config"}
diff --git a/components/layout_thread/lib.rs b/components/layout_thread/lib.rs
index 0010d66673c..589ee822342 100644
--- a/components/layout_thread/lib.rs
+++ b/components/layout_thread/lib.rs
@@ -39,6 +39,7 @@ extern crate script_layout_interface;
 extern crate script_traits;
 extern crate selectors;
 extern crate serde_json;
+extern crate servo_allocator;
 extern crate servo_arc;
 extern crate servo_atoms;
 extern crate servo_config;
@@ -84,7 +85,7 @@ use layout::webrender_helpers::WebRenderDisplayListConverter;
 use layout::wrapper::LayoutNodeLayoutData;
 use layout_traits::LayoutThreadFactory;
 use libc::c_void;
-use malloc_size_of::{malloc_size_of, MallocSizeOf, MallocSizeOfOps};
+use malloc_size_of::{MallocSizeOf, MallocSizeOfOps};
 use metrics::{PaintTimeMetrics, ProfilerMetadataFactory};
 use msg::constellation_msg::PipelineId;
 use msg::constellation_msg::TopLevelBrowsingContextId;
@@ -775,7 +776,7 @@ impl LayoutThread {
         let mut reports = vec![];
         // Servo uses vanilla jemalloc, which doesn't have a
         // malloc_enclosing_size_of function.
-        let mut ops = MallocSizeOfOps::new(malloc_size_of, None, None);
+        let mut ops = MallocSizeOfOps::new(::servo_allocator::usable_size, None, None);
 
         // FIXME(njn): Just measuring the display tree for now.
         let rw_data = possibly_locked_rw_data.lock();
diff --git a/components/malloc_size_of/Cargo.toml b/components/malloc_size_of/Cargo.toml
index afc92cf53a9..05a8f4f4810 100644
--- a/components/malloc_size_of/Cargo.toml
+++ b/components/malloc_size_of/Cargo.toml
@@ -8,9 +8,6 @@ publish = false
 [lib]
 path = "lib.rs"
 
-[target.'cfg(windows)'.dependencies]
-kernel32-sys = "0.2.1"
-
 [features]
 servo = ["js", "string_cache", "url", "webrender_api", "xml5ever"]
 
diff --git a/components/malloc_size_of/lib.rs b/components/malloc_size_of/lib.rs
index 48350e6f840..399f1180637 100644
--- a/components/malloc_size_of/lib.rs
+++ b/components/malloc_size_of/lib.rs
@@ -49,8 +49,6 @@ extern crate euclid;
 extern crate hashglobe;
 #[cfg(feature = "servo")]
 extern crate js;
-#[cfg(target_os = "windows")]
-extern crate kernel32;
 extern crate servo_arc;
 extern crate smallbitvec;
 extern crate smallvec;
@@ -63,8 +61,6 @@ extern crate webrender_api;
 #[cfg(feature = "servo")]
 extern crate xml5ever;
 
-#[cfg(target_os = "windows")]
-use kernel32::{GetProcessHeap, HeapSize, HeapValidate};
 use std::hash::{BuildHasher, Hash};
 use std::mem::size_of;
 use std::ops::Range;
@@ -146,33 +142,6 @@ impl MallocSizeOfOps {
     }
 }
 
-/// Get the size of a heap block.
-#[cfg(not(target_os = "windows"))]
-pub unsafe extern "C" fn malloc_size_of(ptr: *const c_void) -> usize {
-    // The C prototype is `je_malloc_usable_size(JEMALLOC_USABLE_SIZE_CONST void *ptr)`. On some
-    // platforms `JEMALLOC_USABLE_SIZE_CONST` is `const` and on some it is empty. But in practice
-    // this function doesn't modify the contents of the block that `ptr` points to, so we use
-    // `*const c_void` here.
-    extern "C" {
-        #[cfg_attr(any(prefixed_jemalloc, target_os = "macos", target_os = "ios", target_os = "android"),
-                   link_name = "je_malloc_usable_size")]
-        fn malloc_usable_size(ptr: *const c_void) -> usize;
-    }
-    malloc_usable_size(ptr)
-}
-
-/// Get the size of a heap block.
-#[cfg(target_os = "windows")]
-pub unsafe extern "C" fn malloc_size_of(mut ptr: *const c_void) -> usize {
-    let heap = GetProcessHeap();
-
-    if HeapValidate(heap, 0, ptr) == 0 {
-        ptr = *(ptr as *const *const c_void).offset(-1);
-    }
-
-    HeapSize(heap, 0, ptr) as usize
-}
-
 /// Trait for measuring the "deep" heap usage of a data structure. This is the
 /// most commonly-used of the traits.
 pub trait MallocSizeOf {
diff --git a/components/profile/Cargo.toml b/components/profile/Cargo.toml
index d00c0f5000d..6923b0540cf 100644
--- a/components/profile/Cargo.toml
+++ b/components/profile/Cargo.toml
@@ -10,7 +10,7 @@ name = "profile"
 path = "lib.rs"
 
 [features]
-unstable = []
+unstable = ["jemalloc-sys"]
 
 [dependencies]
 profile_traits = {path = "../profile_traits"}
@@ -31,3 +31,4 @@ regex = "0.2"
 
 [target.'cfg(not(target_os = "windows"))'.dependencies]
 libc = "0.2"
+jemalloc-sys = {version = "0.1.3", optional = true}
diff --git a/components/profile/lib.rs b/components/profile/lib.rs
index 96b8edb7e17..d01aad61cd0 100644
--- a/components/profile/lib.rs
+++ b/components/profile/lib.rs
@@ -2,17 +2,14 @@
  * License, v. 2.0. If a copy of the MPL was not distributed with this
  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
 
-#![cfg_attr(all(feature = "unstable", not(target_os = "windows")), feature(alloc_jemalloc))]
-
 #![deny(unsafe_code)]
 
 #[allow(unused_extern_crates)]
-#[cfg(all(feature = "unstable", not(target_os = "windows")))]
-extern crate alloc_jemalloc;
 extern crate heartbeats_simple;
 extern crate influent;
 extern crate ipc_channel;
-#[allow(unused_extern_crates)]
+#[cfg(all(feature = "unstable", not(target_os = "windows")))]
+extern crate jemalloc_sys;
 #[cfg(not(target_os = "windows"))]
 extern crate libc;
 #[macro_use]
diff --git a/components/profile/mem.rs b/components/profile/mem.rs
index 39d3f3ad084..0c9a50ad99d 100644
--- a/components/profile/mem.rs
+++ b/components/profile/mem.rs
@@ -354,7 +354,7 @@ impl ReportsForest {
 
 mod system_reporter {
     #[cfg(all(feature = "unstable", not(target_os = "windows")))]
-    use libc::{c_char, c_void, size_t};
+    use libc::{c_void, size_t};
     #[cfg(target_os = "linux")]
     use libc::c_int;
     use profile_traits::mem::{Report, ReportKind, ReporterRequest};
@@ -460,11 +460,7 @@ mod system_reporter {
     }
 
     #[cfg(all(feature = "unstable", not(target_os = "windows")))]
-    extern {
-        #[cfg_attr(any(target_os = "macos", target_os = "android"), link_name = "je_mallctl")]
-        fn mallctl(name: *const c_char, oldp: *mut c_void, oldlenp: *mut size_t,
-                   newp: *mut c_void, newlen: size_t) -> ::libc::c_int;
-    }
+    use jemalloc_sys::mallctl;
 
     #[cfg(all(feature = "unstable", not(target_os = "windows")))]
     fn jemalloc_stat(value_name: &str) -> Option<usize> {
diff --git a/components/script/Cargo.toml b/components/script/Cargo.toml
index 8c9e9613ede..191a325f60a 100644
--- a/components/script/Cargo.toml
+++ b/components/script/Cargo.toml
@@ -13,7 +13,7 @@ path = "lib.rs"
 
 [features]
 debugmozjs = ['js/debugmozjs']
-unstable = []
+unstable = ["servo_allocator/unstable"]
 
 [build-dependencies]
 cmake = "0.1"
@@ -77,6 +77,7 @@ script_plugins = {path = "../script_plugins"}
 script_traits = {path = "../script_traits"}
 selectors = { path = "../selectors" }
 serde = "1.0"
+servo_allocator = {path = "../allocator"}
 servo_arc = {path = "../servo_arc"}
 servo_atoms = {path = "../atoms"}
 servo_config = {path = "../config"}
diff --git a/components/script/lib.rs b/components/script/lib.rs
index edf954d4c96..df9679bcaf2 100644
--- a/components/script/lib.rs
+++ b/components/script/lib.rs
@@ -78,6 +78,7 @@ extern crate script_layout_interface;
 extern crate script_traits;
 extern crate selectors;
 extern crate serde;
+extern crate servo_allocator;
 extern crate servo_arc;
 #[macro_use] extern crate servo_atoms;
 extern crate servo_config;
diff --git a/components/script/script_thread.rs b/components/script/script_thread.rs
index e5a9a0401aa..991ec777315 100644
--- a/components/script/script_thread.rs
+++ b/components/script/script_thread.rs
@@ -73,7 +73,7 @@ use js::jsapi::{JSAutoCompartment, JSContext, JS_SetWrapObjectCallbacks};
 use js::jsapi::{JSTracer, SetWindowProxyClass};
 use js::jsval::UndefinedValue;
 use js::rust::Runtime;
-use malloc_size_of::{malloc_size_of, MallocSizeOfOps};
+use malloc_size_of::MallocSizeOfOps;
 use mem::malloc_size_of_including_self;
 use metrics::PaintTimeMetrics;
 use microtask::{MicrotaskQueue, Microtask};
@@ -1506,7 +1506,7 @@ impl ScriptThread {
         let mut reports = vec![];
         // Servo uses vanilla jemalloc, which doesn't have a
         // malloc_enclosing_size_of function.
-        let mut ops = MallocSizeOfOps::new(malloc_size_of, None, None);
+        let mut ops = MallocSizeOfOps::new(::servo_allocator::usable_size, None, None);
 
         for (_, document) in self.documents.borrow().iter() {
             let current_url = document.url();
diff --git a/ports/servo/Cargo.toml b/ports/servo/Cargo.toml
index 63803a90f58..4376a0accd0 100644
--- a/ports/servo/Cargo.toml
+++ b/ports/servo/Cargo.toml
@@ -37,7 +37,7 @@ energy-profiling = ["libservo/energy-profiling"]
 debugmozjs = ["libservo/debugmozjs"]
 googlevr = ["libservo/googlevr"]
 oculusvr = ["libservo/oculusvr"]
-unstable = ["libservo/unstable"]
+unstable = ["libservo/unstable", "profile_tests/unstable"]
 
 [dependencies]
 backtrace = "0.3"
diff --git a/python/tidy/servo_tidy/tidy.py b/python/tidy/servo_tidy/tidy.py
index f9571298562..1336c4d0b56 100644
--- a/python/tidy/servo_tidy/tidy.py
+++ b/python/tidy/servo_tidy/tidy.py
@@ -626,6 +626,10 @@ def check_rust(file_name, lines):
                       + decl_found.format(crate_name))
             prev_crate[indent] = crate_name
 
+        if line == "}":
+            for i in [i for i in prev_crate.keys() if i > indent]:
+                del prev_crate[i]
+
         # check alphabetical order of feature attributes in lib.rs files
         if is_lib_rs_file:
             match = re.search(r"#!\[feature\((.*)\)\]", line)
diff --git a/tests/unit/profile/Cargo.toml b/tests/unit/profile/Cargo.toml
index 36dbeb8ffb1..0d04fba813f 100644
--- a/tests/unit/profile/Cargo.toml
+++ b/tests/unit/profile/Cargo.toml
@@ -9,7 +9,13 @@ name = "profile_tests"
 path = "lib.rs"
 doctest = false
 
+[features]
+unstable = ["servo_allocator/unstable"]
+
 [dependencies]
 ipc-channel = "0.9"
 profile = {path = "../../../components/profile"}
 profile_traits = {path = "../../../components/profile_traits"}
+
+# Work around https://github.com/alexcrichton/jemallocator/issues/19
+servo_allocator = {path = "../../../components/allocator"}
diff --git a/tests/unit/profile/lib.rs b/tests/unit/profile/lib.rs
index e07c4908c39..110d8adedb4 100644
--- a/tests/unit/profile/lib.rs
+++ b/tests/unit/profile/lib.rs
@@ -5,6 +5,7 @@
 extern crate ipc_channel;
 extern crate profile;
 extern crate profile_traits;
+extern crate servo_allocator;
 
 #[cfg(test)]
 mod time;