diff --git a/kernel/src/memory/AddressSpace.cpp b/kernel/src/memory/AddressSpace.cpp
index 5ffefe8d..2716110d 100644
--- a/kernel/src/memory/AddressSpace.cpp
+++ b/kernel/src/memory/AddressSpace.cpp
@@ -94,13 +94,14 @@ AddressSpace& AddressSpace::operator=(AddressSpace&& other)
     return *this;
 }
 
-Result<u64> AddressSpace::alloc_region(usize count, int prot, int flags, u64 shmid, bool persistent)
+Result<u64> AddressSpace::alloc_region(usize count, int prot, int flags, off_t offset, u64 shmid, bool persistent)
 {
     auto update_region = [=](VMRegion* region) {
         region->used = true;
         region->persistent = persistent;
         region->prot = prot;
         region->flags = flags;
+        region->offset = offset;
         region->shmid = shmid;
     };
 
@@ -130,7 +131,7 @@ Result<u64> AddressSpace::alloc_region(usize count, int prot, int flags, u64 shm
     return err(ENOMEM);
 }
 
-Result<bool> AddressSpace::set_region(u64 address, usize count, bool used, int prot, int flags, u64 shmid,
+Result<bool> AddressSpace::set_region(u64 address, usize count, bool used, int prot, int flags, off_t offset, u64 shmid,
                                       bool persistent)
 {
     if (address >= VM_END) return err(EINVAL);
@@ -143,6 +144,7 @@ Result<bool> AddressSpace::set_region(u64 address, usize count, bool used, int p
         region->persistent = persistent;
         region->prot = prot;
         region->flags = flags;
+        region->offset = offset;
         region->shmid = shmid;
     };
 
@@ -200,6 +202,23 @@ Result<bool> AddressSpace::set_region(u64 address, usize count, bool used, int p
     return true;
 }
 
+Result<void> AddressSpace::sync_regions(u64 address, usize count)
+{
+    if (address >= VM_END) return err(EINVAL);
+
+    u64 end = address + (count * ARCH_PAGE_SIZE);
+
+    for (auto* region : m_regions)
+    {
+        if (region->end < address) continue;
+        if (region->start > end) return {};
+
+        region->sync_shared();
+    }
+
+    return {};
+}
+
 void AddressSpace::merge_contiguous_regions(VMRegion* a, VMRegion* b)
 {
     a->end = b->end;
@@ -279,3 +298,12 @@ void VMRegion::cleanup_shared()
         }
     }
 }
+
+void VMRegion::sync_shared()
+{
+    if (used && (flags & MAP_SHARED) && (prot & PROT_WRITE))
+    {
+        SharedMemory* shmem = g_shared_memory_map.try_get_ref(shmid);
+        if (shmem) { shmem->inode->write((const u8*)start, offset, count * ARCH_PAGE_SIZE); }
+    }
+}
diff --git a/kernel/src/memory/AddressSpace.h b/kernel/src/memory/AddressSpace.h
index 9a96f51d..a5986f18 100644
--- a/kernel/src/memory/AddressSpace.h
+++ b/kernel/src/memory/AddressSpace.h
@@ -3,6 +3,7 @@
 #include <luna/LinkedList.h>
 #include <luna/OwnedPtr.h>
 #include <luna/Result.h>
+#include <sys/types.h>
 
 class VMRegion : LinkedListNode<VMRegion>
 {
@@ -15,8 +16,10 @@ class VMRegion : LinkedListNode<VMRegion>
     int flags { 0 };
     int prot { 0 };
     u64 shmid;
+    off_t offset { 0 };
 
     void cleanup_shared();
+    void sync_shared();
 };
 
 class AddressSpace
@@ -27,19 +30,21 @@ class AddressSpace
 
     AddressSpace& operator=(AddressSpace&& other);
 
-    Result<u64> alloc_region(usize count, int prot, int flags, u64 shmid = 0, bool persistent = false);
+    Result<u64> alloc_region(usize count, int prot, int flags, off_t offset, u64 shmid = 0, bool persistent = false);
 
-    Result<bool> test_and_alloc_region(u64 address, usize count, int prot, int flags, u64 shmid = 0,
+    Result<bool> test_and_alloc_region(u64 address, usize count, int prot, int flags, off_t offset, u64 shmid = 0,
                                        bool persistent = false)
     {
-        return set_region(address, count, true, prot, flags, shmid, persistent);
+        return set_region(address, count, true, prot, flags, offset, shmid, persistent);
     }
 
     Result<bool> free_region(u64 address, usize count)
     {
-        return set_region(address, count, false, 0, 0, 0, false);
+        return set_region(address, count, false, 0, 0, 0, 0, false);
     }
 
+    Result<void> sync_regions(u64 address, usize count);
+
     static Result<OwnedPtr<AddressSpace>> try_create();
 
     Result<OwnedPtr<AddressSpace>> clone();
@@ -50,7 +55,8 @@ class AddressSpace
     }
 
   private:
-    Result<bool> set_region(u64 address, usize count, bool used, int prot, int flags, u64 shmid, bool persistent);
+    Result<bool> set_region(u64 address, usize count, bool used, int prot, int flags, off_t offset, u64 shmid,
+                            bool persistent);
     Result<void> create_default_region();
     Result<void> create_null_region();
     void try_merge_region_with_neighbors(VMRegion* region);
diff --git a/kernel/src/sys/mmap.cpp b/kernel/src/sys/mmap.cpp
index 3bde30ac..10a2c088 100644
--- a/kernel/src/sys/mmap.cpp
+++ b/kernel/src/sys/mmap.cpp
@@ -16,9 +16,6 @@ Result<u64> sys_mmap(Registers*, SyscallArgs args)
     mmap_params params;
     if (!MemoryManager::copy_from_user_typed((const mmap_params*)args[0], &params)) return err(EFAULT);
 
-    kdbgln("mmap: address=%p, len=%zu, prot=%d, flags=%d, fd=%d, offset=%lu", params.addr, params.len, params.prot,
-           params.flags, params.fd, params.offset);
-
     if (params.len == 0) return err(EINVAL);
 
     if (params.flags < 0) return err(EINVAL);
@@ -58,13 +55,14 @@ Result<u64> sys_mmap(Registers*, SyscallArgs args)
     u64 address;
     if (!params.addr)
         address = TRY(current->address_space->alloc_region(get_blocks_from_size(params.len, ARCH_PAGE_SIZE),
-                                                           params.prot, params.flags, shmid));
+                                                           params.prot, params.flags, params.offset, shmid));
     else
     {
         // FIXME: We should be more flexible if MAP_FIXED was not specified.
         address = align_down<ARCH_PAGE_SIZE>((u64)params.addr);
-        if (!TRY(current->address_space->test_and_alloc_region(
-                address, get_blocks_from_size(params.len, ARCH_PAGE_SIZE), params.prot, params.flags, shmid)))
+        if (!TRY(current->address_space->test_and_alloc_region(address,
+                                                               get_blocks_from_size(params.len, ARCH_PAGE_SIZE),
+                                                               params.prot, params.flags, params.offset, shmid)))
             return err(ENOMEM);
     }
 
@@ -110,3 +108,18 @@ Result<u64> sys_munmap(Registers*, SyscallArgs args)
 
     return { 0 };
 }
+
+Result<u64> sys_msync(Registers*, SyscallArgs args)
+{
+    u64 address = (u64)args[0];
+    usize size = (usize)args[1];
+
+    if (!size) return 0;
+    if (!is_aligned<ARCH_PAGE_SIZE>(address)) return err(EINVAL);
+
+    Thread* current = Scheduler::current();
+
+    TRY(current->address_space->sync_regions(address, get_blocks_from_size(size, ARCH_PAGE_SIZE)));
+
+    return { 0 };
+}
diff --git a/libluna/include/luna/Syscall.h b/libluna/include/luna/Syscall.h
index 57baf9ae..281e13d5 100644
--- a/libluna/include/luna/Syscall.h
+++ b/libluna/include/luna/Syscall.h
@@ -7,7 +7,7 @@
                 _e(fstatat) _e(chdir) _e(getcwd) _e(unlinkat) _e(uname) _e(sethostname) _e(dup2) _e(pipe) _e(mount)    \
                     _e(umount) _e(pstat) _e(getrusage) _e(symlinkat) _e(readlinkat) _e(umask) _e(linkat) _e(faccessat) \
                         _e(pivot_root) _e(sigreturn) _e(sigaction) _e(kill) _e(sigprocmask) _e(setpgid) _e(isatty)     \
-                            _e(getpgid) _e(socket) _e(bind) _e(connect) _e(listen) _e(accept) _e(poll)
+                            _e(getpgid) _e(socket) _e(bind) _e(connect) _e(listen) _e(accept) _e(poll) _e(msync)
 
 enum Syscalls
 {