kvm: x86: Add memcg accounting to KVM allocations

There are many KVM kernel memory allocations which are tied to the life of
the VM process and should be charged to the VM process's cgroup. If the
allocations aren't tied to the process, the OOM killer will not know
that killing the process will free the associated kernel memory.
Add __GFP_ACCOUNT flags to many of the allocations which are not yet being
charged to the VM process's cgroup.

Tested:
	Ran all kvm-unit-tests on a 64 bit Haswell machine, the patch
	introduced no new failures.
	Ran a kernel memory accounting test which creates a VM to touch
	memory and then checks that the kernel memory allocated for the
	process is within certain bounds.
	With this patch we account for much more of the vmalloc and slab memory
	allocated for the VM.

There remain a few allocations which should be charged to the VM's
cgroup but are not. In x86, they include:
	vcpu->arch.pio_data
There allocations are unaccounted in this patch because they are mapped
to userspace, and accounting them to a cgroup causes problems. This
should be addressed in a future patch.

Signed-off-by: Ben Gardon <bgardon@google.com>
Reviewed-by: Shakeel Butt <shakeelb@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

1 files changed, 3 insertions, 3 deletions

diff --git a/arch/x86/kvm/mmu.c b/arch/x86/kvm/mmu.c
index 45eb988aa411..415d0e62cb3e 100644
--- a/arch/x86/kvm/mmu.c
+++ b/arch/x86/kvm/mmu.c
@@ -961,7 +961,7 @@ static int mmu_topup_memory_cache(struct kvm_mmu_memory_cache *cache,
 	if (cache->nobjs >= min)
 		return 0;
 	while (cache->nobjs < ARRAY_SIZE(cache->objects)) {
-		obj = kmem_cache_zalloc(base_cache, GFP_KERNEL);
+		obj = kmem_cache_zalloc(base_cache, GFP_KERNEL_ACCOUNT);
 		if (!obj)
 			return cache->nobjs >= min ? 0 : -ENOMEM;
 		cache->objects[cache->nobjs++] = obj;
@@ -3702,7 +3702,7 @@ static int mmu_alloc_shadow_roots(struct kvm_vcpu *vcpu)
 
 			u64 *lm_root;
 
-			lm_root = (void*)get_zeroed_page(GFP_KERNEL);
+			lm_root = (void*)get_zeroed_page(GFP_KERNEL_ACCOUNT);
 			if (lm_root == NULL)
 				return 1;
 
@@ -5499,7 +5499,7 @@ static int alloc_mmu_pages(struct kvm_vcpu *vcpu)
 	 * Therefore we need to allocate shadow page tables in the first
 	 * 4GB of memory, which happens to fit the DMA32 zone.
 	 */
-	page = alloc_page(GFP_KERNEL | __GFP_DMA32);
+	page = alloc_page(GFP_KERNEL_ACCOUNT | __GFP_DMA32);
 	if (!page)
 		return -ENOMEM;