Re: [PATCH v2 5/6] mm: memory: use folio_prealloc() in wp_page_copy()

[Vishal Moola <vishal.moola@gmail.com>]

On Mon, Nov 13, 2023 at 11:22:21PM +0800, Kefeng Wang wrote:
> Use folio_prealloc() helper to simplify code a bit.

Reviewed-by: Vishal Moola (Oracle) <vishal.moola@gmail.com>

> Signed-off-by: Kefeng Wang <wangkefeng.wang@huawei.com>
> ---
>  mm/memory.c | 22 +++++++---------------
>  1 file changed, 7 insertions(+), 15 deletions(-)
> 
> diff --git a/mm/memory.c b/mm/memory.c
> index f350ab2a324f..03226566bf8e 100644
> --- a/mm/memory.c
> +++ b/mm/memory.c
> @@ -3114,6 +3114,7 @@ static vm_fault_t wp_page_copy(struct vm_fault *vmf)
>  	int page_copied = 0;
>  	struct mmu_notifier_range range;
>  	vm_fault_t ret;
> +	bool pfn_is_zero;
>  
>  	delayacct_wpcopy_start();
>  
> @@ -3123,16 +3124,13 @@ static vm_fault_t wp_page_copy(struct vm_fault *vmf)
>  	if (unlikely(ret))
>  		goto out;
>  
> -	if (is_zero_pfn(pte_pfn(vmf->orig_pte))) {
> -		new_folio = vma_alloc_zeroed_movable_folio(vma, vmf->address);
> -		if (!new_folio)
> -			goto oom;
> -	} else {
> +	pfn_is_zero = is_zero_pfn(pte_pfn(vmf->orig_pte));
> +	new_folio = folio_prealloc(mm, vma, vmf->address, pfn_is_zero);
> +	if (!new_folio)
> +		goto oom;
> +
> +	if (!pfn_is_zero) {
>  		int err;
> -		new_folio = vma_alloc_folio(GFP_HIGHUSER_MOVABLE, 0, vma,
> -				vmf->address, false);
> -		if (!new_folio)
> -			goto oom;
>  
>  		err = __wp_page_copy_user(&new_folio->page, vmf->page, vmf);
>  		if (err) {
> @@ -3153,10 +3151,6 @@ static vm_fault_t wp_page_copy(struct vm_fault *vmf)
>  		kmsan_copy_page_meta(&new_folio->page, vmf->page);
>  	}
>  
> -	if (mem_cgroup_charge(new_folio, mm, GFP_KERNEL))
> -		goto oom_free_new;
> -	folio_throttle_swaprate(new_folio, GFP_KERNEL);
> -
>  	__folio_mark_uptodate(new_folio);
>  
>  	mmu_notifier_range_init(&range, MMU_NOTIFY_CLEAR, 0, mm,
> @@ -3255,8 +3249,6 @@ static vm_fault_t wp_page_copy(struct vm_fault *vmf)
>  
>  	delayacct_wpcopy_end();
>  	return 0;
> -oom_free_new:
> -	folio_put(new_folio);
>  oom:
>  	ret = VM_FAULT_OOM;
>  out:
> -- 
> 2.27.0