Re: [PATCH] kvm: do not account temporary allocations to kmem

[Sean Christopherson <seanjc@google.com>]

On Mon, Jun 10, 2024, Alexey Dobriyan wrote:
> Some allocations done by KVM are temporary, they are created as result
> of program actions, but can't exists for arbitrary long times.
> 
> They should have been GFP_TEMPORARY (rip!).

Wouldn't GFP_USER be more appropriate for all of these?  E.g. KVM_SET_REGS uses
memdup_user() and thus GFP_USER.
 
> OTOH, kvm-nx-lpage-recovery and kvm-pit kernel threads exist for as long
> as VM exists but their task_struct memory is not accounted.
> This is story for another day.
> 
> Signed-off-by: Alexey Dobriyan <adobriyan@gmail.com>
> ---
> 
>  virt/kvm/kvm_main.c |   11 +++++------
>  1 file changed, 5 insertions(+), 6 deletions(-)
> 
> --- a/virt/kvm/kvm_main.c
> +++ b/virt/kvm/kvm_main.c
> @@ -4427,7 +4427,7 @@ static long kvm_vcpu_ioctl(struct file *filp,
>  		struct kvm_regs *kvm_regs;
>  
>  		r = -ENOMEM;
> -		kvm_regs = kzalloc(sizeof(struct kvm_regs), GFP_KERNEL_ACCOUNT);
> +		kvm_regs = kzalloc(sizeof(struct kvm_regs), GFP_KERNEL);
>  		if (!kvm_regs)
>  			goto out;
>  		r = kvm_arch_vcpu_ioctl_get_regs(vcpu, kvm_regs);
> @@ -4454,8 +4454,7 @@ static long kvm_vcpu_ioctl(struct file *filp,
>  		break;
>  	}
>  	case KVM_GET_SREGS: {
> -		kvm_sregs = kzalloc(sizeof(struct kvm_sregs),
> -				    GFP_KERNEL_ACCOUNT);
> +		kvm_sregs = kzalloc(sizeof(struct kvm_sregs), GFP_KERNEL);
>  		r = -ENOMEM;
>  		if (!kvm_sregs)
>  			goto out;
> @@ -4547,7 +4546,7 @@ static long kvm_vcpu_ioctl(struct file *filp,
>  		break;
>  	}
>  	case KVM_GET_FPU: {
> -		fpu = kzalloc(sizeof(struct kvm_fpu), GFP_KERNEL_ACCOUNT);
> +		fpu = kzalloc(sizeof(struct kvm_fpu), GFP_KERNEL);
>  		r = -ENOMEM;
>  		if (!fpu)
>  			goto out;
> @@ -6210,7 +6209,7 @@ static void kvm_uevent_notify_change(unsigned int type, struct kvm *kvm)
>  	active = kvm_active_vms;
>  	mutex_unlock(&kvm_lock);
>  
> -	env = kzalloc(sizeof(*env), GFP_KERNEL_ACCOUNT);
> +	env = kzalloc(sizeof(*env), GFP_KERNEL);
>  	if (!env)
>  		return;
>  
> @@ -6226,7 +6225,7 @@ static void kvm_uevent_notify_change(unsigned int type, struct kvm *kvm)
>  	add_uevent_var(env, "PID=%d", kvm->userspace_pid);
>  
>  	if (!IS_ERR(kvm->debugfs_dentry)) {
> -		char *tmp, *p = kmalloc(PATH_MAX, GFP_KERNEL_ACCOUNT);
> +		char *tmp, *p = kmalloc(PATH_MAX, GFP_KERNEL);
>  
>  		if (p) {
>  			tmp = dentry_path_raw(kvm->debugfs_dentry, p, PATH_MAX);