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@xxxxxxxxxx>
---
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;
}
