Re: [PATCH 4/6] mm: memory: use a folio in do_cow_page()

[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

 





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;
  }





[Index of Archives]     [Linux ARM Kernel]     [Linux ARM]     [Linux Omap]     [Fedora ARM]     [IETF Annouce]     [Bugtraq]     [Linux OMAP]     [Linux MIPS]     [eCos]     [Asterisk Internet PBX]     [Linux API]

  Powered by Linux