Re: [PATCH -next] KVM: SVM: Remove unnecessary GFP_KERNEL_ACCOUNT in svm_set_nested_state()

[Huang, Kai]

On 21/08/2024 11:27 pm, Yongqiang Liu wrote:
> The fixed size temporary variables vmcb_control_area and vmcb_save_area
> allocated in svm_set_nested_state() are released when the function exits.
> Meanwhile, svm_set_nested_state() also have vcpu mutex held to avoid
> massive concurrency allocation, so we don't need to set GFP_KERNEL_ACCOUNT.

Hi Sean/Paolo,

Seems more patches are popping up regarding to whether to use _ACCOUNT 
for temporary memory allocation.  Could we have a definitive guide on this?

As you know, one similar patch was merged and now is in upstream:

  dd103407ca315 ("KVM: X86: Remove unnecessary GFP_KERNEL_ACCOUNT for 
temporary variables")

Also see:

https://lore.kernel.org/kvm/20240715101224.90958-1-kai.huang@xxxxxxxxx/T/

> Signed-off-by: Yongqiang Liu <liuyongqiang13@xxxxxxxxxx>
> ---
>   arch/x86/kvm/svm/nested.c | 4 ++--
>   1 file changed, 2 insertions(+), 2 deletions(-)
>
> diff --git a/arch/x86/kvm/svm/nested.c b/arch/x86/kvm/svm/nested.c
> index 6f704c1037e5..d5314cb7dff4 100644
> --- a/arch/x86/kvm/svm/nested.c
> +++ b/arch/x86/kvm/svm/nested.c
> @@ -1693,8 +1693,8 @@ static int svm_set_nested_state(struct kvm_vcpu *vcpu,
>   		return -EINVAL;
>   
>   	ret  = -ENOMEM;
> -	ctl  = kzalloc(sizeof(*ctl),  GFP_KERNEL_ACCOUNT);
> -	save = kzalloc(sizeof(*save), GFP_KERNEL_ACCOUNT);
> +	ctl  = kzalloc(sizeof(*ctl),  GFP_KERNEL);
> +	save = kzalloc(sizeof(*save), GFP_KERNEL);
>   	if (!ctl || !save)
>   		goto out_free;
>