On 06/04/21 21:07, Sean Christopherson wrote:
Use GFP_KERNEL_ACCOUNT when allocating vCPUs to make it more obvious that that the allocations are accounted, to make it easier to audit KVM's allocations in the future, and to be consistent with other cache usage in KVM. When using SLAB/SLUB, this is a nop as the cache itself is created with SLAB_ACCOUNT. When using SLOB, there are caveats within caveats. SLOB doesn't honor SLAB_ACCOUNT, so passing GFP_KERNEL_ACCOUNT will result in vCPU allocations now being accounted. But, even that depends on internal SLOB details as SLOB will only go to the page allocator when its cache is depleted. That just happens to be extremely likely for vCPUs because the size of kvm_vcpu is larger than the a page for almost all combinations of architecture and page size. Whether or not the SLOB behavior is by design is unknown; it's just as likely that no SLOB users care about accounding and so no one has bothered to implemented support in SLOB. Regardless, accounting vCPU allocations will not break SLOB+KVM+cgroup users, if any exist. Cc: Wanpeng Li <kernellwp@xxxxxxxxx> Signed-off-by: Sean Christopherson <seanjc@xxxxxxxxxx> --- v2: Drop the Fixes tag and rewrite the changelog since this is a nop when using SLUB or SLAB. [Wanpeng] virt/kvm/kvm_main.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c index 0a481e7780f0..580f98386b42 100644 --- a/virt/kvm/kvm_main.c +++ b/virt/kvm/kvm_main.c @@ -3192,7 +3192,7 @@ static int kvm_vm_ioctl_create_vcpu(struct kvm *kvm, u32 id) if (r) goto vcpu_decrement;- vcpu = kmem_cache_zalloc(kvm_vcpu_cache, GFP_KERNEL);+ vcpu = kmem_cache_zalloc(kvm_vcpu_cache, GFP_KERNEL_ACCOUNT); if (!vcpu) { r = -ENOMEM; goto vcpu_decrement;
Queued, thanks. Paolo
