Method remove_userspace_mapping

vmm/src/memory_manager.rs:2374–2428

# Safety `userspace_addr` and `memory_size` must have previously been passed to `create_userspace_mapping`. # Errors If this function fails there is no way to clean up resources and you should probably crash the process.

(
        &mut self,
        guest_phys_addr: u64,
        memory_size: usize,
        userspace_addr: *mut u8,
        mergeable: bool,
        slot: u32,
    )

    /// If this function fails there is no way to clean up resources and you
    /// should probably crash the process.
    pub unsafe fn remove_userspace_mapping(
        &mut self,
        guest_phys_addr: u64,
        memory_size: usize,
        userspace_addr: *mut u8,
        mergeable: bool,
        slot: u32,
    ) -> Result<(), Error> {
        // SAFETY: Caller promises parameters are correct.
        unsafe {
            self.vm
                .remove_user_memory_region(
                    slot,
                    guest_phys_addr,
                    memory_size,
                    userspace_addr,
                    false, /* readonly -- don't care */
                    false, /* log dirty */
                )
                .map_err(Error::RemoveUserMemoryRegion)?;
        }

        // Mark the pages as unmergeable if there were previously marked as
        // mergeable.
        if mergeable {
            // SAFETY: the address and size are valid as the region was
            // previously advised.
            let ret = unsafe {
                libc::madvise(
                    userspace_addr.cast(),
                    memory_size as libc::size_t,
                    libc::MADV_UNMERGEABLE,
                )
            };
            if ret != 0 {
                let err = io::Error::last_os_error();
                // Safe to unwrap because the error is constructed with
                // last_os_error(), which ensures the output will be Some().
                let errno = err.raw_os_error().unwrap();
                if errno == libc::EINVAL {
                    warn!("kernel not configured with CONFIG_KSM");
                } else {
                    warn!("madvise error: {err}");
                }
                warn!("failed to mark pages as unmergeable");
            }
        }

        info!(
            "Removed userspace mapping: {guest_phys_addr:x} -> {userspace_addr_:x} {memory_size:x}",
            userspace_addr_ = userspace_addr as u64
        );

        Ok(())
    }

    pub fn virtio_mem_resize(&mut self, id: &str, size: u64) -> Result<(), Error> {
        if let Some(memory_zone) = self.memory_zones.get_mut(id) {