On Mon, Nov 13, 2023 at 11:22:20PM +0800, Kefeng Wang wrote:
> Use folio_prealloc() helper and convert to use a folio in
> do_cow_page(), which save five compound_head() calls.
s/do_cow_page()/do_cow_fault()/
Aside from that,
Reviewed-by: Vishal Moola (Oracle) <vishal.moola@xxxxxxxxx>
> Signed-off-by: Kefeng Wang <wangkefeng.wang@xxxxxxxxxx>
> ---
> mm/memory.c | 16 ++++++----------
> 1 file changed, 6 insertions(+), 10 deletions(-)
>
> diff --git a/mm/memory.c b/mm/memory.c
> index d85df1c59f52..f350ab2a324f 100644
> --- a/mm/memory.c
> +++ b/mm/memory.c
> @@ -4653,6 +4653,7 @@ static vm_fault_t do_read_fault(struct vm_fault *vmf)
> static vm_fault_t do_cow_fault(struct vm_fault *vmf)
> {
> struct vm_area_struct *vma = vmf->vma;
> + struct folio *folio;
> vm_fault_t ret;
>
> ret = vmf_can_call_fault(vmf);
> @@ -4661,16 +4662,11 @@ static vm_fault_t do_cow_fault(struct vm_fault *vmf)
> if (ret)
> return ret;
>
> - vmf->cow_page = alloc_page_vma(GFP_HIGHUSER_MOVABLE, vma, vmf->address);
> - if (!vmf->cow_page)
> + folio = folio_prealloc(vma->vm_mm, vma, vmf->address, false);
> + if (!folio)
> return VM_FAULT_OOM;
>
> - if (mem_cgroup_charge(page_folio(vmf->cow_page), vma->vm_mm,
> - GFP_KERNEL)) {
> - put_page(vmf->cow_page);
> - return VM_FAULT_OOM;
> - }
> - folio_throttle_swaprate(page_folio(vmf->cow_page), GFP_KERNEL);
> + vmf->cow_page = &folio->page;
>
> ret = __do_fault(vmf);
> if (unlikely(ret & (VM_FAULT_ERROR | VM_FAULT_NOPAGE | VM_FAULT_RETRY)))
> @@ -4679,7 +4675,7 @@ static vm_fault_t do_cow_fault(struct vm_fault *vmf)
> return ret;
>
> copy_user_highpage(vmf->cow_page, vmf->page, vmf->address, vma);
> - __SetPageUptodate(vmf->cow_page);
> + __folio_mark_uptodate(folio);
>
> ret |= finish_fault(vmf);
> unlock_page(vmf->page);
> @@ -4688,7 +4684,7 @@ static vm_fault_t do_cow_fault(struct vm_fault *vmf)
> goto uncharge_out;
> return ret;
> uncharge_out:
> - put_page(vmf->cow_page);
> + folio_put(folio);
> return ret;
> }
>
> --
> 2.27.0
