Messages in this thread | | | Date | Wed, 8 Nov 2023 09:41:32 +0800 | Subject | Re: [PATCH 4/6] mm: memory: use a folio in do_cow_page() | From | Kefeng Wang <> |
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On 2023/11/8 2:27, Sidhartha Kumar wrote: > On 11/7/23 5:52 AM, Kefeng Wang wrote: >> Use folio_prealloc() helper and convert to use a folio in >> do_cow_page(), which save five compound_head() calls. >> >> Signed-off-by: Kefeng Wang <wangkefeng.wang@huawei.com> >> --- >> mm/memory.c | 16 ++++++---------- >> 1 file changed, 6 insertions(+), 10 deletions(-) >> >> diff --git a/mm/memory.c b/mm/memory.c >> index 062136d25da3..5ecee3eac29d 100644 >> --- a/mm/memory.c >> +++ b/mm/memory.c >> @@ -4648,6 +4648,7 @@ 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); >> @@ -4656,16 +4657,11 @@ 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); > > Hi Kefeng, > > I was wondering why this block of code is no longer needed after using a > folio?
folio_prealloc(previous page_copy_prealloc) already with above code.
> > Thanks, > Sidhartha Kumar > >> + vmf->cow_page = &folio->page; >> ret = __do_fault(vmf); >> if (unlikely(ret & (VM_FAULT_ERROR | VM_FAULT_NOPAGE | >> VM_FAULT_RETRY))) >> @@ -4674,7 +4670,7 @@ 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); >> @@ -4683,7 +4679,7 @@ 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; >> } >
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