On Thu, Apr 18, 2013 at 09:38:14AM -0700, Andrew Honig wrote:
>
> If userspace creates and destroys multiple VMs within the same process
> we leak 20k of memory in the userspace process context per VM. This
> patch frees the memory in kvm_arch_destroy_vm. If the process exits
> without closing the VM file descriptor or the file descriptor has been
> shared with another process then we don't free the memory.
>
> It's still possible for a user space process to leak memory if the last
> process to close the fd for the VM is not the process that created it.
> However, this is an unexpected case that's only caused by a user space
> process that's misbehaving.
>
> Signed-off-by: Andrew Honig <[email protected]>
Reviewed-by: Gleb Natapov <[email protected]>
> ---
> arch/x86/kvm/x86.c | 17 +++++++++++++++++
> 1 file changed, 17 insertions(+)
>
> diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
> index 8ffac42..3b389bf 100644
> --- a/arch/x86/kvm/x86.c
> +++ b/arch/x86/kvm/x86.c
> @@ -6856,6 +6856,23 @@ void kvm_arch_sync_events(struct kvm *kvm)
>
> void kvm_arch_destroy_vm(struct kvm *kvm)
> {
> + if (current->mm == kvm->mm) {
> + /*
> + * Free memory regions allocated on behalf of userspace,
> + * unless the the memory map has changed due to process exit
> + * or fd copying.
> + */
> + struct kvm_userspace_memory_region mem;
> + memset(&mem, 0, sizeof(mem));
> + mem.slot = APIC_ACCESS_PAGE_PRIVATE_MEMSLOT;
> + kvm_set_memory_region(kvm, &mem);
> +
> + mem.slot = IDENTITY_PAGETABLE_PRIVATE_MEMSLOT;
> + kvm_set_memory_region(kvm, &mem);
> +
> + mem.slot = TSS_PRIVATE_MEMSLOT;
> + kvm_set_memory_region(kvm, &mem);
> + }
> kvm_iommu_unmap_guest(kvm);
> kfree(kvm->arch.vpic);
> kfree(kvm->arch.vioapic);
> --
> 1.7.10.4
>
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--
Gleb.
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