Re: [PATCH v8 1/3] mm: add new api to enable ksm per process

[Stefan Roesch <shr@devkernel.io>]

David Hildenbrand <david@redhat.com> writes:

>> +static void __ksm_add_vma(struct vm_area_struct *vma)
>> +{
>> +	unsigned long vm_flags = vma->vm_flags;
>> +
>> +	if (vm_flags & VM_MERGEABLE)
>> +		return;
>> +
>> +	if (vma_ksm_compatible(vma)) {
>> +		vm_flags |= VM_MERGEABLE;
>> +		vm_flags_reset(vma, vm_flags);
>> +	}
>> +}
>
> We can do the following simplification on top:
>
> diff --git a/mm/ksm.c b/mm/ksm.c
> index 905c8edce5cf..26e7f585d65d 100644
> --- a/mm/ksm.c
> +++ b/mm/ksm.c
> @@ -2511,15 +2511,11 @@ static int ksm_scan_thread(void *nothing)
>
>  static void __ksm_add_vma(struct vm_area_struct *vma)
>  {
> -	unsigned long vm_flags = vma->vm_flags;
> -
> -	if (vm_flags & VM_MERGEABLE)
> +	if (vma->vm_flags & VM_MERGEABLE)
>  		return;
>
> -	if (vma_ksm_compatible(vma)) {
> -		vm_flags |= VM_MERGEABLE;
> -		vm_flags_reset(vma, vm_flags);
> -	}
> +	if (vma_ksm_compatible(vma))
> +		vm_flags_set(vma, VM_MERGEABLE);
>  }
>
>  /**
> --
> 2.39.2
>
>

The next version has the above change.

> I have some patches based on your patch set (handling/testing unmerging whens
> setting PR_SET_MEMORY_MERGE=0. Will send out once you changes are queued.