diff --git a/crate/memory/src/memory_set/handler/mod.rs b/crate/memory/src/memory_set/handler/mod.rs
index 6154e964..9a17732b 100644
--- a/crate/memory/src/memory_set/handler/mod.rs
+++ b/crate/memory/src/memory_set/handler/mod.rs
@@ -41,11 +41,11 @@ pub trait FrameAllocator: Debug + Clone + Send + Sync + 'static {
 
 mod byframe;
 mod delay;
-mod linear;
 mod file;
+mod linear;
 //mod swap;
 
 pub use self::byframe::ByFrame;
 pub use self::delay::Delay;
-pub use self::linear::Linear;
 pub use self::file::{File, Read};
+pub use self::linear::Linear;
diff --git a/kernel/Cargo.lock b/kernel/Cargo.lock
index f9d9c2b2..c1dd7a09 100644
--- a/kernel/Cargo.lock
+++ b/kernel/Cargo.lock
@@ -102,7 +102,7 @@ dependencies = [
 
 [[package]]
 name = "buddy_system_allocator"
-version = "0.1.2"
+version = "0.3.4"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 dependencies = [
  "spin 0.5.0 (registry+https://github.com/rust-lang/crates.io-index)",
@@ -367,7 +367,7 @@ dependencies = [
  "bitmap-allocator 0.1.0 (git+https://github.com/rcore-os/bitmap-allocator)",
  "bitvec 0.11.0 (git+https://github.com/myrrlyn/bitvec.git)",
  "bootloader 0.4.0 (git+https://github.com/rcore-os/bootloader)",
- "buddy_system_allocator 0.1.2 (registry+https://github.com/rust-lang/crates.io-index)",
+ "buddy_system_allocator 0.3.4 (registry+https://github.com/rust-lang/crates.io-index)",
  "cc 1.0.31 (registry+https://github.com/rust-lang/crates.io-index)",
  "console-traits 0.3.0 (registry+https://github.com/rust-lang/crates.io-index)",
  "device_tree 1.0.3 (git+https://github.com/rcore-os/device_tree-rs)",
@@ -661,7 +661,7 @@ source = "registry+https://github.com/rust-lang/crates.io-index"
 "checksum bitvec 0.11.0 (git+https://github.com/myrrlyn/bitvec.git)" = "<none>"
 "checksum bitvec 0.9.0 (registry+https://github.com/rust-lang/crates.io-index)" = "cfadef5c4e2c2e64067b9ecc061179f12ac7ec65ba613b1f60f3972bbada1f5b"
 "checksum bootloader 0.4.0 (git+https://github.com/rcore-os/bootloader)" = "<none>"
-"checksum buddy_system_allocator 0.1.2 (registry+https://github.com/rust-lang/crates.io-index)" = "2ed828f1e227d6e32b998d6375b67fd63ac5389d50b23f258ce151d22b6cc595"
+"checksum buddy_system_allocator 0.3.4 (registry+https://github.com/rust-lang/crates.io-index)" = "94a6c0143a07fea0db2f4b43cb9540dcc7c17af8a7beafdf2184e5e4e35aae91"
 "checksum byteorder 1.3.1 (registry+https://github.com/rust-lang/crates.io-index)" = "a019b10a2a7cdeb292db131fc8113e57ea2a908f6e7894b0c3c671893b65dbeb"
 "checksum cc 1.0.31 (registry+https://github.com/rust-lang/crates.io-index)" = "c9ce8bb087aacff865633f0bd5aeaed910fe2fe55b55f4739527f2e023a2e53d"
 "checksum cfg-if 0.1.7 (registry+https://github.com/rust-lang/crates.io-index)" = "11d43355396e872eefb45ce6342e4374ed7bc2b3a502d1b28e36d6e23c05d1f4"
diff --git a/kernel/Cargo.toml b/kernel/Cargo.toml
index 2483a420..8ef38d74 100644
--- a/kernel/Cargo.toml
+++ b/kernel/Cargo.toml
@@ -57,7 +57,7 @@ volatile = "0.2"
 heapless = "0.4"
 bitvec = { git = "https://github.com/myrrlyn/bitvec.git", default-features = false, features = ["alloc"] }
 console-traits = "0.3"
-buddy_system_allocator = "0.1"
+buddy_system_allocator = "0.3"
 pci = { git = "https://github.com/rcore-os/pci-rs" }
 device_tree = { git = "https://github.com/rcore-os/device_tree-rs" }
 isomorphic_drivers = { git = "https://github.com/rcore-os/isomorphic_drivers" }
diff --git a/kernel/src/fs/mod.rs b/kernel/src/fs/mod.rs
index 256ce5ea..419e3eb9 100644
--- a/kernel/src/fs/mod.rs
+++ b/kernel/src/fs/mod.rs
@@ -9,15 +9,15 @@ use crate::arch::driver::ide;
 pub use self::file::*;
 pub use self::file_like::*;
 pub use self::pipe::Pipe;
-pub use self::stdio::{STDIN, STDOUT};
 pub use self::pseudo::*;
+pub use self::stdio::{STDIN, STDOUT};
 
 mod device;
 mod file;
 mod file_like;
 mod pipe;
-mod stdio;
 mod pseudo;
+mod stdio;
 
 /// Hard link user programs
 #[cfg(feature = "link_user")]
diff --git a/kernel/src/fs/pseudo.rs b/kernel/src/fs/pseudo.rs
index 6da58c03..fdcc5358 100644
--- a/kernel/src/fs/pseudo.rs
+++ b/kernel/src/fs/pseudo.rs
@@ -14,7 +14,7 @@ impl Pseudo {
     pub fn new(s: &str, type_: FileType) -> Self {
         Pseudo {
             content: Vec::from(s.as_bytes()),
-            type_
+            type_,
         }
     }
 }
diff --git a/kernel/src/lib.rs b/kernel/src/lib.rs
index fa5f0a65..b6c482c1 100644
--- a/kernel/src/lib.rs
+++ b/kernel/src/lib.rs
@@ -18,7 +18,7 @@ extern crate log;
 extern crate lazy_static;
 
 pub use crate::process::{new_kernel_context, processor};
-use buddy_system_allocator::LockedHeap;
+use buddy_system_allocator::LockedHeapWithRescue;
 use rcore_thread::std_thread as thread;
 
 #[macro_use] // print!
@@ -65,4 +65,5 @@ pub fn kmain() -> ! {
 ///
 /// It should be defined in memory mod, but in Rust `global_allocator` must be in root mod.
 #[global_allocator]
-static HEAP_ALLOCATOR: LockedHeap = LockedHeap::empty();
+static HEAP_ALLOCATOR: LockedHeapWithRescue =
+    LockedHeapWithRescue::new(crate::memory::enlarge_heap);
diff --git a/kernel/src/memory.rs b/kernel/src/memory.rs
index 8367cbc6..f34354f7 100644
--- a/kernel/src/memory.rs
+++ b/kernel/src/memory.rs
@@ -14,14 +14,17 @@
 
 use super::HEAP_ALLOCATOR;
 pub use crate::arch::paging::*;
-use crate::consts::MEMORY_OFFSET;
+use crate::consts::{KERNEL_OFFSET, MEMORY_OFFSET};
 use crate::process::process_unsafe;
 use crate::sync::SpinNoIrqLock;
+use alloc::boxed::Box;
+use alloc::vec::Vec;
 use bitmap_allocator::BitAlloc;
-use buddy_system_allocator::LockedHeap;
+use buddy_system_allocator::{Heap, LockedHeap};
 use lazy_static::*;
 use log::*;
 pub use rcore_memory::memory_set::{handler::*, MemoryArea, MemoryAttr};
+use rcore_memory::paging::PageTable;
 use rcore_memory::*;
 
 pub type MemorySet = rcore_memory::memory_set::MemorySet<InactivePageTable0>;
@@ -145,5 +148,32 @@ pub fn init_heap() {
     info!("heap init end");
 }
 
-/// Allocator for the rest memory space on NO-MMU case.
-pub static MEMORY_ALLOCATOR: LockedHeap = LockedHeap::empty();
+pub fn enlarge_heap(heap: &mut Heap) {
+    let mut page_table = active_table();
+    let mut addrs = [(0, 0); 32];
+    let mut addr_len = 0;
+    let va_offset = KERNEL_OFFSET + 0xe0000000;
+    for i in 0..16384 {
+        let page = alloc_frame().unwrap();
+        let va = KERNEL_OFFSET + 0xe0000000 + page;
+        if addr_len > 0 {
+            let (ref mut addr, ref mut len) = addrs[addr_len-1];
+            if *addr - PAGE_SIZE == va {
+                *len += PAGE_SIZE;
+                *addr -= PAGE_SIZE;
+                continue;
+            }
+        }
+        addrs[addr_len] = (va, PAGE_SIZE);
+        addr_len += 1;
+    }
+    for (addr, len) in addrs[..addr_len].into_iter() {
+        for va in (*addr..(*addr + *len)).step_by(PAGE_SIZE) {
+            page_table.map(va, va - va_offset).update();
+        }
+        info!("Adding {:#X} {:#X} to heap", addr, len);
+        unsafe {
+            heap.init(*addr, *len);
+        }
+    }
+}
diff --git a/kernel/src/syscall/mod.rs b/kernel/src/syscall/mod.rs
index 066d0a64..3f183d88 100644
--- a/kernel/src/syscall/mod.rs
+++ b/kernel/src/syscall/mod.rs
@@ -31,8 +31,8 @@ mod net;
 mod proc;
 mod time;
 
-use spin::Mutex;
 use alloc::collections::BTreeMap;
+use spin::Mutex;
 
 #[cfg(feature = "profile")]
 lazy_static! {
@@ -45,9 +45,7 @@ lazy_static! {
 #[deny(unreachable_patterns)]
 pub fn syscall(id: usize, args: [usize; 6], tf: &mut TrapFrame) -> isize {
     #[cfg(feature = "profile")]
-    let begin_time = unsafe {
-        core::arch::x86_64::_rdtsc()
-    };
+    let begin_time = unsafe { core::arch::x86_64::_rdtsc() };
     let cid = cpu::id();
     let pid = process().pid.clone();
     let tid = processor().tid();
@@ -268,9 +266,7 @@ pub fn syscall(id: usize, args: [usize; 6], tf: &mut TrapFrame) -> isize {
     }
     #[cfg(feature = "profile")]
     {
-        let end_time = unsafe {
-            core::arch::x86_64::_rdtsc()
-        };
+        let end_time = unsafe { core::arch::x86_64::_rdtsc() };
         *SYSCALL_TIMING.lock().entry(id).or_insert(0) += end_time - begin_time;
         if end_time % 1000 == 0 {
             let timing = SYSCALL_TIMING.lock();
diff --git a/user b/user
index 05f0efd3..aec8667e 160000
--- a/user
+++ b/user
@@ -1 +1 @@
-Subproject commit 05f0efd3fda084109e4b6da8ff30ecb1557a267f
+Subproject commit aec8667eb056cb564e301d6c0937da1e4500a4d3