mm, kvm: account kvm_vcpu_mmap to kmemcg

A VCPU of a VM can allocate couple of pages which can be mmap'ed by the
user space application. At the moment this memory is not charged to the
memcg of the VMM. On a large machine running large number of VMs or
small number of VMs having large number of VCPUs, this unaccounted
memory can be very significant. So, charge this memory to the memcg of
the VMM. Please note that lifetime of these allocations corresponds to
the lifetime of the VMM.

Link: https://lkml.kernel.org/r/20201106202923.2087414-1-shakeelb@google.comSigned-off-by: Shakeel Butt <shakeelb@google.com>
Acked-by: Roman Gushchin <guro@fb.com>
Acked-by: Paolo Bonzini <pbonzini@redhat.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Michal Hocko <mhocko@suse.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

arch/x86/kvm/x86.c

@@ -9869,7 +9869,7 @@ int kvm_arch_vcpu_create(struct kvm_vcpu *vcpu)
 
 	r = -ENOMEM;
 
-	page = alloc_page(GFP_KERNEL | __GFP_ZERO);
+	page = alloc_page(GFP_KERNEL_ACCOUNT | __GFP_ZERO);
 	if (!page)
 		goto fail_free_lapic;
 	vcpu->arch.pio_data = page_address(page);

virt/kvm/coalesced_mmio.c

@@ -111,7 +111,7 @@ int kvm_coalesced_mmio_init(struct kvm *kvm)
 {
 	struct page *page;
 
-	page = alloc_page(GFP_KERNEL | __GFP_ZERO);
+	page = alloc_page(GFP_KERNEL_ACCOUNT | __GFP_ZERO);
 	if (!page)
 		return -ENOMEM;
 

virt/kvm/kvm_main.c

@@ -3116,7 +3116,7 @@ static int kvm_vm_ioctl_create_vcpu(struct kvm *kvm, u32 id)
 	}
 
 	BUILD_BUG_ON(sizeof(struct kvm_run) > PAGE_SIZE);
-	page = alloc_page(GFP_KERNEL | __GFP_ZERO);
+	page = alloc_page(GFP_KERNEL_ACCOUNT | __GFP_ZERO);
 	if (!page) {
 		r = -ENOMEM;
 		goto vcpu_free;