diff --git a/core/ksyscall/Cargo.toml b/core/ksyscall/Cargo.toml
index abc551edf99834ffb1e572a8ba7e934cf534f6b8..6f3817fbc7f0294a8cc6b787c1d9c29b80a96d51 100644
--- a/core/ksyscall/Cargo.toml
+++ b/core/ksyscall/Cargo.toml
@@ -20,6 +20,7 @@ tee_ta_sign = ["tee_task_iface?/tee_ta_sign"]
 ebpf = ["dep:posix-bpf", "posix-bpf/ebpf", "posix-fs/ebpf"]
 
 [dependencies]
+kalloc.workspace = true
 kaddr_layout.workspace = true
 kfd_objects.workspace = true
 kfutex.workspace = true
diff --git a/core/ksyscall/src/sys.rs b/core/ksyscall/src/sys.rs
index 8f658a808a11c6f398dc400696e76d65e515cc4e..343f833b1b938ddd4cbaa61b36f161866969149c 100644
--- a/core/ksyscall/src/sys.rs
+++ b/core/ksyscall/src/sys.rs
@@ -11,6 +11,7 @@
 
 use kbuild_config::ARCH;
 use kerrno::KResult;
+use khal::mem;
 use kprocess::{current_user_process, current_user_process_fs_context};
 use kvfs::{Filename, NodePermission};
 use linux_raw_sys::{
@@ -99,6 +100,13 @@ pub fn sys_sysinfo(info: UserPtr<sysinfo>) -> KResult<isize> {
     };
     kinfo.procs = kprocess::system_view::process_count() as _;
     kinfo.mem_unit = 1;
+
+    let alloc = kalloc::global_allocator();
+    let avail = alloc.available_pages();
+    let total_pages = alloc.used_pages() + avail;
+    kinfo.totalram = total_pages.saturating_mul(mem::PAGE_SIZE_4K) as _;
+    kinfo.freeram = avail.saturating_mul(mem::PAGE_SIZE_4K) as _;
+
     info.write_vm(kinfo)?;
     Ok(0)
 }
diff --git a/mm/filemap/src/shared.rs b/mm/filemap/src/shared.rs
index ba8bffabd6bdd18e1600dde0ed44e74eaca01b47..6660aa9d44263603bd4eb8ebf6cc11980bf87251 100644
--- a/mm/filemap/src/shared.rs
+++ b/mm/filemap/src/shared.rs
@@ -339,9 +339,9 @@ impl FileSharedRuntime {
         range: VirtAddrRange,
         policy: MsyncPolicy,
     ) -> KResult<MsyncRuntimeResult> {
-        if policy.has_invalidate() {
-            return Err(KError::OperationNotSupported);
-        }
+        // MS_ASYNC (and MS_INVALIDATE) are no-ops at the VMA level —
+        // Linux never actually evicts or zaps pages for MS_INVALIDATE
+        // because the page cache is globally coherent.
         if !policy.is_sync() {
             return Ok(MsyncRuntimeResult::Synced);
         }
diff --git a/mm/memspace/src/aspace.rs b/mm/memspace/src/aspace.rs
index 5b5bfa60f93a1f1e639d9c0c4b66bf5b0fd9db36..f12d3d52450e4d1845dc4747d6c651504ad19d67 100644
--- a/mm/memspace/src/aspace.rs
+++ b/mm/memspace/src/aspace.rs
@@ -1208,9 +1208,6 @@ impl MmSpace {
         if size == 0 {
             return Ok(());
         }
-        if policy.has_invalidate() {
-            return Err(KError::OperationNotSupported);
-        }
 
         let range = VirtAddrRange::from_start_size(start, size);
         let overlapped_vmas = self.vmas.collect_overlapping(range);
@@ -1223,6 +1220,8 @@ impl MmSpace {
             }
             let overlap = VirtAddrRange::new(cursor.max(vma.start()), range.end.min(vma.end()));
             if !overlap.is_empty() {
+                // TODO: when mlock is implemented, check VM_LOCKED and
+                // return EBUSY for MS_INVALIDATE as Linux does.
                 let runtime = self.runtime_for_vma(&vma).ok_or(KError::BadAddress)?;
                 runtime.msync(&vma, overlap, policy)?;
             }
diff --git a/posix/mm/docs/security.md b/posix/mm/docs/security.md
index e2827877d333d7c518322d45ca5142d861248f8f..4d9165141c5ee20e037353f8ce3887295bbc388d 100644
--- a/posix/mm/docs/security.md
+++ b/posix/mm/docs/security.md
@@ -90,7 +90,7 @@
 | `munmap` 范围非法 | 长度为 0 或下游地址空间拒绝 | 返回错误 | 不修改地址空间 |
 | `mprotect` grow flag 不支持 | `PROT_GROWSDOWN` 或 `PROT_GROWSUP` | 返回错误 | protect 失败，不修改 PTE/VMA |
 | `MADV_DONTNEED` 范围非法 | 地址未映射、未页对齐、或 `addr + len` 溢出 | 返回错误 | advice 失败，不修改对象 |
-| `msync` flag 不支持 | unknown flags、`MS_ASYNC | MS_SYNC`、或 `MS_INVALIDATE` | 返回错误 | sync 失败，不修改对象 |
+| `msync` flag 不支持 | unknown flags 或 `MS_ASYNC | MS_SYNC` 组合 | 返回错误 | sync 失败，不修改对象 |
 | shared file writeback 失败 | VFS `AddressSpaceOperations::writepages()` 失败 | 返回错误，dirty bit 保留 | syscall 失败，调用者可重试 |
 
 ## 故障管理