On Fri, Feb 03, 2023 at 09:16:35PM +0800, Yin Fengwei wrote:
> do_set_pte_range() allows to setup page table entries for a
> specific range. It calls folio_add_file_rmap_range() to take
> advantage of batched rmap update for large folio.
>
> Signed-off-by: Yin Fengwei <fengwei.yin@xxxxxxxxx>
> ---
> include/linux/mm.h | 3 +++
> mm/filemap.c | 1 -
> mm/memory.c | 59 ++++++++++++++++++++++++++++++----------------
> 3 files changed, 42 insertions(+), 21 deletions(-)
>
> diff --git a/include/linux/mm.h b/include/linux/mm.h
> index d6f8f41514cc..93192f04b276 100644
> --- a/include/linux/mm.h
> +++ b/include/linux/mm.h
> @@ -1162,6 +1162,9 @@ static inline pte_t maybe_mkwrite(pte_t pte, struct vm_area_struct *vma)
>
> vm_fault_t do_set_pmd(struct vm_fault *vmf, struct page *page);
> void do_set_pte(struct vm_fault *vmf, struct page *page, unsigned long addr);
> +void do_set_pte_range(struct vm_fault *vmf, struct folio *folio,
> + unsigned long addr, pte_t *pte,
> + unsigned long start, unsigned int nr);
>
> vm_fault_t finish_fault(struct vm_fault *vmf);
> vm_fault_t finish_mkwrite_fault(struct vm_fault *vmf);
> diff --git a/mm/filemap.c b/mm/filemap.c
> index f444684db9f2..74046a3a0ff5 100644
> --- a/mm/filemap.c
> +++ b/mm/filemap.c
> @@ -3386,7 +3386,6 @@ static vm_fault_t filemap_map_folio_range(struct vm_fault *vmf,
>
> ref_count++;
> do_set_pte(vmf, page, addr);
> - update_mmu_cache(vma, addr, vmf->pte);
> } while (vmf->pte++, page++, addr += PAGE_SIZE, ++count < nr_pages);
>
> /* Restore the vmf->pte */
> diff --git a/mm/memory.c b/mm/memory.c
> index 7a04a1130ec1..3754b2ef166a 100644
> --- a/mm/memory.c
> +++ b/mm/memory.c
> @@ -4257,36 +4257,58 @@ vm_fault_t do_set_pmd(struct vm_fault *vmf, struct page *page)
> }
> #endif
>
> -void do_set_pte(struct vm_fault *vmf, struct page *page, unsigned long addr)
> +void do_set_pte_range(struct vm_fault *vmf, struct folio *folio,
> + unsigned long addr, pte_t *pte,
> + unsigned long start, unsigned int nr)
> {
> struct vm_area_struct *vma = vmf->vma;
> bool uffd_wp = pte_marker_uffd_wp(vmf->orig_pte);
> bool write = vmf->flags & FAULT_FLAG_WRITE;
> + bool cow = write && !(vma->vm_flags & VM_SHARED);
Why don't use is_cow_mapping()?
Is there anything messed up with VM_MAYWRITE?
> bool prefault = vmf->address != addr;
> + struct page *page = folio_page(folio, start);
> pte_t entry;
>
> - flush_icache_page(vma, page);
> - entry = mk_pte(page, vma->vm_page_prot);
> + if (!cow) {
> + folio_add_file_rmap_range(folio, start, nr, vma, false);
> + add_mm_counter(vma->vm_mm, mm_counter_file(page), nr);
> + }
>
> - if (prefault && arch_wants_old_prefaulted_pte())
> - entry = pte_mkold(entry);
> - else
> - entry = pte_sw_mkyoung(entry);
> + do {
> + flush_icache_page(vma, page);
> + entry = mk_pte(page, vma->vm_page_prot);
>
> - if (write)
> - entry = maybe_mkwrite(pte_mkdirty(entry), vma);
> - if (unlikely(uffd_wp))
> - entry = pte_mkuffd_wp(entry);
> - /* copy-on-write page */
> - if (write && !(vma->vm_flags & VM_SHARED)) {
> + if (prefault && arch_wants_old_prefaulted_pte())
> + entry = pte_mkold(entry);
> + else
> + entry = pte_sw_mkyoung(entry);
> +
> + if (write)
> + entry = maybe_mkwrite(pte_mkdirty(entry), vma);
> + if (unlikely(uffd_wp))
> + entry = pte_mkuffd_wp(entry);
> + set_pte_at(vma->vm_mm, addr, pte, entry);
> +
> + /* no need to invalidate: a not-present page won't be cached */
> + update_mmu_cache(vma, addr, pte);
> + } while (pte++, page++, addr += PAGE_SIZE, --nr > 0);
> +}
> +
> +void do_set_pte(struct vm_fault *vmf, struct page *page, unsigned long addr)
> +{
> + struct folio *folio = page_folio(page);
> + struct vm_area_struct *vma = vmf->vma;
> + bool cow = (vmf->flags & FAULT_FLAG_WRITE) &&
> + !(vma->vm_flags & VM_SHARED);
Here too.
> +
> + if (cow) {
> inc_mm_counter(vma->vm_mm, MM_ANONPAGES);
> page_add_new_anon_rmap(page, vma, addr);
> lru_cache_add_inactive_or_unevictable(page, vma);
> - } else {
> - inc_mm_counter(vma->vm_mm, mm_counter_file(page));
> - page_add_file_rmap(page, vma, false);
> }
> - set_pte_at(vma->vm_mm, addr, vmf->pte, entry);
> +
> + do_set_pte_range(vmf, folio, addr, vmf->pte,
> + folio_page_idx(folio, page), 1);
> }
>
> static bool vmf_pte_changed(struct vm_fault *vmf)
> @@ -4361,9 +4383,6 @@ vm_fault_t finish_fault(struct vm_fault *vmf)
> if (likely(!vmf_pte_changed(vmf))) {
> do_set_pte(vmf, page, vmf->address);
>
> - /* no need to invalidate: a not-present page won't be cached */
> - update_mmu_cache(vma, vmf->address, vmf->pte);
> -
> ret = 0;
> } else {
> update_mmu_tlb(vma, vmf->address, vmf->pte);
> --
> 2.30.2
>
>
Thanks,
Chih-En Lin
